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All about solar power [2016 latest version]
Solar power. It uses sunlight to generate eco-friendly electricity that does not emit CO2. However, with all the talk about the bursting of the solar bubble, have you ever wondered what the future holds for solar power generation? However, if you are considering whether to install solar power on the roof of your home, we recommend installing it with confidence.
We've put together all the questions you might have about solar installations. By the time you finish reading you will be a solar power doctor.
Before reading the article…If you change the power company, you can save an average of 31,266 yen per year!This is the average annual savings for the plan that ranked first in electricity bill savings in the simulation result of selecting a three-person household in the Enechange Power Comparison Diagnosis. The savings amount includes benefits such as gift certificates (simulation period/October 14, 2021 to January 26, 2022)
More than 10 million households nationwide have already switched electricity providers. Next, let's start saving smart electricity bills by switching electric power companies. Search for electric power companies in the area where you live! Enter your zip code and start comparing electric power companies!What about solar power generation? I asked the salesperson!
Before explaining various questions about solar power generation, I would like to briefly ask the question, "What about solar power generation?" I asked Mr. A who works!
The image is an image.
I don't know... (laughs). I don't think it's sold very well lately. The purchase price of electricity has fallen, and the solar bubble has burst. It's been a while since the earthquake, and the demand for eco-friendly products is fading. In the first place, it is also big that the number of newly built buildings is decreasing.
No, not really. Even if the purchase price drops, you can recover the cost of the equipment in 10 to 15 years, and after that you will continue to earn income from selling electricity.
I know you said this all the time, but will the solar power generation system never break down? I hear there are some problems...
The solar panel itself hardly deteriorates and does not break (see Not maintenance free for details on deterioration). The oldest solar power plant in Japan has been in operation for over 30 years. However, I wonder if the power conditioner will need to be replaced in about 10 years. Many manufacturers offer 15+ year warranties on solar panels and 10+ year warranties on inverters. Basically, if you install it properly, you can generate electricity for a long time with almost no deterioration.
I see... I'm about to write an article about solar power generation, but after all, is solar power generation recommended for people?
I always tell my customers that if it were me, I would definitely wear it. Buying solar is often likened to a car in terms of cost, but unlike a car, solar always pays for itself. Even if I can't work, only sunlight will continue to work. Above all, it is an eco-friendly energy source and is kind to the earth. There are no disadvantages other than the initial investment, and although I am in the position of sales, I recommend it with confidence.
I see! thank you.
According to Mr. A, solar power generation is cost-recoverable and environmentally friendly. After doing some research, I've come to the same basic conclusion. However, it is also true that there are a number of points to note when introducing solar power. With that in mind, let’s take a look at all things solar power!
Basic Knowledge of Photovoltaic Power Generation
Photovoltaic power generation can be used for a variety of purposes by converting the energy of the sun that pours down into electricity. A device that converts sunlight into electricity is a "solar cell", and in English it is called Photovoltic, or PV for short. Here, we first introduce the mechanism of solar cells, and then look at the basic structure of a photovoltaic power generation system using solar cells. Solar cells that make up a solar panel. I'm sure you've all seen them on calculators and wristwatches. Whether it's a small solar cell like the one in the photo or a solar power generation facility called a mega-solar, the structure is exactly the same. Let's start talking about solar power generation by briefly explaining how these black plates generate electricity.Solar cells use semiconductors to convert light into electricity. Although it is called a "battery", it is not really a battery because it does not have the function of storing electricity. Its basic mechanism is to generate electricity by moving electrons in solar cells with the power of light. See the diagram below.
How Solar Cells Generate ElectricityImage Source: Solar cells are made by combining two types of semiconductors (n-type and p-type) with different electrical properties. A semiconductor is a substance that conducts or does not conduct electricity depending on the conditions. When the electrons in the solar cell are exposed to light, energy accumulates (photoelectric effect) and they start moving. A solar cell generates electricity by inducing them with two types of semiconductors and pushing them out to an external electric circuit.
Flow of ElectricityFrom these properties, we can say the following two characteristics of solar cells.
Power generation using solar cells with these properties is photovoltaic power generation.
Solar cells using the semiconductors introduced (pn junction type) are currently in practical use, but research is also progressing on new solar cells called dye-sensitized solar cells. It uses the electrons in the dye, and has several advantages over the conventional silicon type.
Advantages of Dye-Sensitized Solar CellsIn 2008, a solar car using dye-sensitized solar cells completed the race, and now it seems that it is just one step away from practical use. Currently, solar cells are large and heavy, but in the near future, they may be attached to walls, windows, and other places to generate electricity.
I explained that solar cells use two types of semiconductors to conduct electrons and generate electricity, but they can be divided into several types depending on the material.
There are many types, but the following four types are currently used for solar power generation in Japan.Each has its own characteristics. Let's see!
Characteristics of different types of solar cells
| System | Type | Module conversion efficiency | Major domestic manufacturers | Characteristics |
|---|---|---|---|---|
| Silicon-based | Single crystal | 13-20% | Toshiba, Sharp, etc. | Popular for residential use. |
| Polycrystalline | 12-16% | Sharp, Kyocera, etc. | Many industrial uses. | |
| Heterojunction (HIT) | 18-19% | Panasonic | Popular for residential use. | |
| Compound System | CIS | 13-14% | Solar Frontier | Less deterioration over time. |
In Japan, as prices drop due to intensifying competition, the popularity of monocrystalline silicon solar cells is increasing, and many domestic manufacturers are starting to manufacture them. has become
It seems that foreign manufacturers often sell this polycrystalline panel, which is the mainstream overseas.
Panasonic manufactures HIT solar cells, which use monocrystalline silicon, and accounts for most of the share of heterojunction solar cells distributed in Japan. On the other hand, Kaneka sells products that use polycrystals, and instead of sacrificing conversion efficiency, we manufacture products that are thin and rich in design.
Until 2014, Honda Soltech manufactured CIGS solar cells using additional gallium (Ga), but lost the price competition and withdrew, and is no longer manufacturing them.
Currently, manufacturers are competing fiercely over conversion efficiency and price. The conversion efficiency will increase and the price will decrease.
There are some solar cells other than those commercialized in Japan. Let's take a quick look at its features.
Okay, now that we've figured out how to generate electricity from sunlight, let's take a look at the solar power system that operates it. This system is basically the same for home use, industrial use, and mega solar. The mechanism itself is simple, so let's understand it step by step!
Image quote:
Explanation of each itemIn industrial photovoltaic power generation systems, when receiving power from a commercial power system (6.6 kV, etc.), it is necessary to have a "receiving and transforming facility" that transforms it into low-voltage power or lighting power as necessary. It may become.
Let's see how the generated electricity flows!
Flow of electricity in a solar power generation systemWhen the generated electricity is not enough to cover the consumption, such as at night or in rainy weather, electricity is purchased from the electric power company. On the other hand, when the amount of electricity generated exceeds the amount used during the daytime when the weather is fine and there is surplus electricity, it is sent to the electricity network. Sending electricity to the electricity network in this way is called "reverse power flow" (in contrast, the flow from the power company to the home is called "tidal flow").
The photovoltaic power generation system is connected to a large electricity network.
Electricity has the property of flowing from high voltage to low voltage. Like water, it flows from high places to low places. If you use electricity at home, you will run out of electricity, so your home voltage will be low. It feels like the water level in my electric pond is low. Then, the voltage becomes lower than that of the distribution line, so the electricity flows to your home, which is the "tidal current" that is the flow of electricity from the power company to your home. On the other hand, if the amount of electricity generated exceeds the amount used at home, the voltage will rise. The water level in your electric pond is high. Then the voltage will be higher than that of the distribution line, and the electricity will flow backwards from the house to the distribution line. This is a mechanism of reverse power flow, and it is a mechanism that can sell electricity.
There are various types of solar power generation. It varies greatly depending on the scale, from the one on the roof of a private house to the one with solar panels lined up on sunny land.
There are three types of solar power introduced, depending on the amount of power (kW) introduced.
Let's take a look at the installation cost of residential solar power generation by installed capacity (kW). Solar power was once likened to a luxury car. What is the current price?
An important concept when considering the cost of solar power generation is the "kW unit price", which is the total amount including the main unit price and construction costs divided by the amount of power generated (kW). It's a simple indicator of how much it costs per kW to install, and it's almost always featured in solar advertisements. Let's take an example. Two companies that sell solar power for the roof of your house have provided quotes.
In this case, Company A's kW unit price is 370,000 yen, and Company B's is 417,000 yen. In terms of price, Company B is cheaper, but in terms of cost-effectiveness, Company A's proposal is more profitable.
According to the "Opinion on Procurement Price and Procurement Period for Fiscal Year 2016 (Draft)" announced on February 22, 2016, the predicted kW unit price for fiscal 2016 is 353,000 yen (with an obligation to install output control compatible equipment). +10,000 yen/kW).
Since the capacity of solar power generation installed on the roof of a typical Japanese house is about 3 to 5 kW, the cost by capacity is shown below.
Estimated cost by introduction volume
| Initial cost | Number of modules installed (for 250W) | |
|---|---|---|
| 3kW | 1,059,000 yen | 12 pieces |
| 4kW | 1,412,000 yen | 16 |
| 5 kW | 1,765,000 yen | 20 | td>
Please confirm how many kW you should actually install for ordinary households.
The kW unit price is obtained from "All costs". Some companies display the kW unit price without including the monitor fee or electricity sales meter fee in order to make it look cheap, but this ignores the understanding of the market price. That kW unit price of the ad you're looking at right now. Please check if you really want from all expenses.
History and Terminology of Photovoltaic Power Generation ~Japan used to be the world's No.1~
Did you know that Japan used to have the world's largest installed capacity of photovoltaic power generation? In terms of production volume, four companies, including Sharp, accounted for the top five companies, and Japan was a solar power generation powerhouse. But as of 2016, those days are over. Here, let's understand the various terms and circumstances related to solar power generation while following the history of solar power generation in Japan!
The history of solar power generation in Japan Let's look at them one by one. You can see various things related to sunlight.The first oil shock in 1973 and the second oil shock from 1978 to 1983 caused oil prices to soar, and the world economy, which was dependent on petroleum energy at that time, was in turmoil. As a result, energy conservation was called for, and energy sources other than petroleum were sought. Since then, the diversification of energy sources and the improvement of energy self-sufficiency have been the foundations of Japan's energy strategy.
One of them was renewable energy, solar power.
The Agency for Natural Resources and Energy explains renewable energy as follows.
Solar power, wind power, water power, geothermal heat, solar heat, heat in the atmosphere and other natural heat, and biomass are stipulated as "things that can be used permanently as energy sources." . Renewable energy is an excellent energy resource that can be used repeatedly without depletion, and emits almost no carbon dioxide, which causes global warming, during power generation and heat utilization.
Source: What is renewable energy?
and specifically
etc. Energy produced by thermal power generation using oil or natural gas, and energy produced by nuclear power generation using uranium, etc. are not renewable energy.
In 1993, for the first time in Japan, Sanyo Electric Co., Ltd. (currently Panasonic Corporation) installed a residential solar power generation system. Solar power generation equipment at that time was very expensive, 15 million yen for 4KW! Even so, the number of people who are interested in new technologies and who are installing solar power generation in their homes from the perspective of energy conservation continued to increase.
Since 1994, subsidies have been provided at the time of purchase, and the amount of solar power generation introduced in Japan has become the highest in the world! It symbolizes the high environmental awareness of the Japanese people and the richness of the time.
However, in 2004, Germany introduced the FIT system to solar power, and the amount of introduction increased explosively. After that, the FIT system was introduced in Spain, and the high purchase price sparked speculation around the world, creating a solar bubble. On the other hand, Japan stopped subsidies in 2005 and the amount of introduction decreased, and as of 2010, it has fallen to the third place in the world.
International Comparison of Installed Amounts as of 2010The government panicked by this, considered reviving subsidies and introducing the FIT system in Japan, and in 2009 partially introduced it for solar power generation. start.
However, it can be said that the greatness of the introduction of solar power generation in Japan was not the simple "quantity", but the high introduction rate of residential solar power generation. The high share of residential solar power means that there is a decentralized power source in urban areas. This means that there is a disaster-resistant power supply in the city, and it is more advantageous than building a huge solar facility in a mountainous area. This was a clear result of ordinary Japanese people's serious concern for the environment and their individual actions for the environment. Image quote:
What is the FIT system? CommentaryThis FIT system has dramatically increased the amount introduced in Germany and Spain. The official name is Feed-in Tariff, and in Japanese it is called "Fixed Price Purchase System". Originally invented in the United States, it has become a popular method for popularizing renewable energy. When trying to introduce solar power, etc., the cost of equipment becomes a major obstacle. Even if you sell the electricity you make, if the purchase price is low, it is difficult to make a high capital investment. Therefore, the FIT system is a system in which the government sets a purchase price higher than the general electricity price and compensates for it for a certain period (10 years for residential use and 20 years for industrial use in the case of solar power). By providing a long-term purchase guarantee, the purpose is to make it easier to set a prospect for recovering the initial investment, encourage investment and financing, and increase the proportion of renewable energy. While the subsidy system merely subsidizes the purchase of equipment, the FIT system guarantees a longer period of time. But there is one thing that worries me. This FIT system purchases electricity derived from renewable energy for a long period of time at a higher price than the selling price. Do you know who is paying the difference? The correct answer is us, the general public. To be precise, it would be better to say everyone who uses electricity. A renewable energy surcharge is added to regular electricity bills. The renewable energy surcharge in FY2015 is 1.58 yen per kW in the case of low voltage, so if one household's annual electricity consumption is 5156 kWh (according to the Quantitative Analysis Unit of the Institute of Energy Economics, Japan 2014), the annual burden per household is about 8,146 yen. (Monthly average 678 yen). Since the purchase period for residential solar power generation is 10 years and for industrial use is 20 years, the renewable energy levy will decrease from around 2020, but it is estimated that it will rise to a maximum of about 3 yen per kW.
From July 2012, the FIT system will be introduced in Japan. Momentum for renewable energy is increasing due to the power shortage caused by the Great East Japan Earthquake and the shift from nuclear power generation, and a purchase price (40 yen/kWh for industrial use), which is about twice the international standard, was set. In addition, a system to purchase all electricity, which had not been approved until then, was approved, and the foundation for the solar power generation business was established. And it was also decided to maintain a high purchase price for the three years after the enforcement as a profit consideration period! The fact that the public bears the burden is one of the reasons why this high price has been recognized.
In addition, the tax saving effect of the "green investment tax reduction" that allows immediate depreciation of capital investment, the effective use of idle land that is abundant in various parts of Japan, and the fact that environmental assessment is unnecessary. Together, these have led to a surge of investment in solar power generation. In addition, the purchase price is uniform for industrial use of 10 kW or more, and the larger the scale, the better the business feasibility, so large-scale solar power generation facilities (mega solar) were built throughout Japan.
Why did the solar bubble occur![All about Solar Power [2016 Latest version]](https://website-google-hk.oss-cn-hongkong.aliyuncs.com/drawing/article_results_9/2022/3/28/6e478aaa1e176464bf4bc3a2623cd33c_2.jpeg "All about solar power [2016 latest version]")
As of November 2012, immediately after the introduction of the FIT system, the certified installed capacity of wind power and others was 388,000 kW, while solar power was 3,260,000 kW, more than eight times higher. The FIT system will heat up solar investment. As a result, 94% of the 88,000,000 kW certified equipment by the end of fiscal 2014, after the three-year profit consideration period, was for photovoltaic power generation. And Japan's cumulative introduction amount has increased explosively, becoming the third largest in the world after Germany and China.
Ranking of installed solar power generation by country in the worldAlso, domestic installation, which once accounted for 95% for residential use, has changed significantly due to the large-scale introduction of industrial use and mega solar.
Changes in the amount of solar power installed in JapanAs you can see from the above figure, the FIT system and the solar bubble it causes have led to explosive growth in the amount of industrial and mega solar installations. I understand. Image quote:
The introduction of solar power, which has exploded due to the solar bubble, finally causes a certain problem. Take a look at the table below.
Status of connection capacity and connection application volume of electric power companies (January 2015)Source: You can see that the certified capacity greatly exceeds the connection capacity enclosed in the red frame. If more photovoltaic power generation is connected than can be connected, the voltage of the entire distribution network will rise, causing a bank reverse power flow problem that interferes with normal power flow. power distribution system up to). In response to this situation, in September 2014, Kyushu Electric Power suspended all applications for connection, including existing and new ones, and Hokkaido, Tohoku, Shikoku, and Okinawa Electric Power, which were in similar situations, followed suit. This shocked many businesses who were planning to start a solar power business, and in January 2015, the system was changed to effectively limit the introduction of solar power. When linking high-voltage and extra-high-voltage equipment of 50 kW or more, the installer bears the construction costs for bank reverse power flow countermeasures. This will serve as an opportunity to reflect on and reform Japan's FIT system.
In the three-year profit consideration period, the amount of solar power introduced in Japan and the proportion of renewable energy increased. In the future, the main focus will be on curbing the introduction of large-scale solar power generation, expanding residential solar power generation, and promoting the introduction of other renewable energy sources. Up until now, we have blindly expanded the amount of energy we have introduced, but we are now at the stage where we are looking for more efficient ways to use energy while saving energy in light of technological advances.
Future renewable energy will be expanded in the following directions.
The government plans to announce an energy innovation strategy in March 2016, and it seems that they are moving in the direction of thorough energy conservation, such as the introduction of the top runner system. Solar power generation is also changing to an era where you use the electricity you make yourself instead of installing solar power generation on the roof just to sell electricity. The future trend of solar power is shifting from electricity-selling houses to energy-creating houses, especially zero-energy houses.
Zero Energy Homes (ZEH) are homes with zero energy balance.
Specifically, it refers to a house that has the following facilities, and the amount of energy used and consumed becomes plus or minus zero.
Equipping Zero-Energy HousesIn addition to improving energy-saving performance to reduce energy consumption, the government plans to introduce a new type of house that uses photovoltaic power generation to cover the annual primary energy consumption. We aim to have zero-energy homes standardized by 2020. Subsidies have been provided since 2012 and are expected to be provided in 2016 as well. Misawa Homes has announced that all new construction sales in fiscal 2017 will be zero-energy homes, and PanaHome has announced that it will achieve 85% in fiscal 2018. In the future, new construction will become more and more zero-energy homes.
Actually, solar power generation itself is not currently subsidized except for some local governments. In the future, subsidies will be applied to comprehensive systems that combine HEMS and storage batteries, and will be energy self-sufficient zero-energy homes. The era of solar power that simply generates and sells electricity is over.
Benefits and Significance of Solar Power
I hope you now have a good understanding of what solar power is and what it is all about. Let's take a closer look at the benefits of solar energy.
Photovoltaic power generation is a renewable energy source that emits no harmful substances, not to mention CO2, during power generation. This is very important these days when global warming is called out.
See the diagram below. Source: You can see that the CO2 emissions from solar power generation is about 1/20th that of oil-fired power generation, which accounts for about half of Japan's power generation, making it an environmentally friendly power generation method.
This ability to generate your own electricity is the biggest advantage of solar power for both individuals and government strategies. Being able to generate your own power means that you become the director of a small power plant, and the government strategically means that many small power plants can be built in the city.
Becoming the head of a small power plantUntil now, the electricity produced by the power company was simply flowing from the outlet. Whether we liked it or not, we had no choice but to buy electricity generated by thermal or nuclear power plants. However, if you install solar power generation, most of the electricity you use can be occupied by eco-electricity. If you install solar power, you will be able to actively participate in the flow of electricity!
The fact that there are many small power plantsThe spread of renewable energy, including solar power generation, is also the most important issue in Japan!
Installing a solar power system will reduce your electricity bill!
……Many manufacturers and dealers are advertising, but that is because the graph of solar power generation and power consumption is as follows.
Electricity usage diagram of the surplus purchase system for general householdsSource: Let's organize it.
In other words, the electricity bill during the day and the electricity bill for the electricity sold will be cheaper. If the sum of these two exceeds the cost of electricity, the cost of electricity will disappear and a profit will be made. Although it depends on the scale and situation of installing solar power generation, if you install 3 kW or more, you will be able to cover the electricity bill of a family of 4 and earn income from selling electricity. See our 4kW installation simulation to see how much money you can get and how many years it will pay for itself.
In addition to solar power generation, if you make an all-electric house that unifies all the energy used at home to electricity, you can reduce the overall utility costs. Surprisingly, according to Panasonic's trial calculation, it is possible to reduce utility costs by 100% by making an all-electric home in addition to solar power generation! According to Fuji Keizai's 2014 survey of trends in energy-creating housing and all-electric homes showing new developments due to the full liberalization of the electricity retail market, all-electric homes, which were 5.62 million in 2013, will increase by 2025. 10.29 million households in 2020, and 1 in 5 households is expected to be all-electric. However, it seems that it is not enough to just look at it because the utility bills will be cheaper after the earthquake.
The trend of the times is energy-creating houses with all-electric and solar power generation, but it is important to understand the merits and demerits properly when introducing them.
Please see this article for more information about all-electricity that may reduce utility costs to zero.
Thorough introduction to the advantages and disadvantages of all-electric
This is solar power as an investment, where you can sell electricity and make a profit. You can make money by selling electricity, whether it's for residential use or mega-solar for investment.
In the case of residential solar power generation (10 kW or less), as explained above, if the amount of power generated during the day exceeds the amount used, the surplus can be sold. This is called the surplus purchase system. On the other hand, for photovoltaic power generation of 10 kW or more, you can choose between this surplus purchase system and the total purchase system. See the diagram below.
The full purchase system is a system in which electric power companies purchase all the electricity that is generated, regardless of the quality of the electricity. Mega solar for investment and photovoltaic power generation installed in buildings etc. are making profits in this way. Especially for industrial use, the FIT system promises fixed purchases for 20 years, so investment was concentrated. This is the solar bubble.Thanks to the system that can sell this electricity reliably, even for residential use, depending on the scale, even after recovering the initial cost, it will make a profit.
Did you know that there are times when electricity is expensive and times when it is cheap?
Prices are high during the day when the demand for electricity is high, and low in the morning and at night when the demand is low. If you use solar power to supplement daytime electricity, you don't have to use that expensive electricity, so it's a good deal.
Sometimes you can save more than 10,000 yen a year on your electricity bill just by changing to an electricity bill plan that suits your lifestyle.
Find a great electricity rate plan now!
Also, power companies have their own power plants to avoid blackouts during peak daytime hours in the summer. If photovoltaic power generation spreads, it will be possible to reduce the amount of electricity used during the peak daytime (this is called the peak cut effect), and it will be possible to cut costs significantly in this area. That way, you can lower your electricity bills. This is another big advantage of solar power.
Disadvantages and Problems of Solar Power Generation
Next, let's look at the disadvantages of solar power generation.
As I saw in the chapter on cost, in order to install 4kW, it is necessary to anticipate a budget of about 1.5 million yen. It's just like buying a car, isn't it?
The electric power business is a typical capital investment business, and it requires patience to recover the high initial investment in units of 10 years. It cannot be said that there will be a collapse of the house or a drastic change in the social situation before the original funds are recovered. The biggest risk of solar power generation is that the initial investment is large and it takes time to recover.
Suddenly, if solar power generation systems with the same capacity and conditions are installed in "Naha City (Okinawa Prefecture)", "Matsumoto City (Nagano Prefecture)", and "Tokyo", which city will generate the most predicted power generation? do you think?
Is it Naha with good sunshine? You might think that, but surprisingly, Matsumoto City has the largest amount of estimated annual power generation. This is because sunshine hours and temperature are important factors in the amount of power generated, and if it's too hot, it's no good. See the diagram below. Estimated annual power generation by region announced by Choshu Sangyo.
Estimated annual power generation of 4.96 kW systems nationwide (Choshu Sangyo) It is true that the amount of power generated by solar cells increases when the sun is shining for a long time and there is strong sunlight.Please see the diagram on the left. You can see that the maximum output decreases as the temperature rises. At 60°C, the output of crystalline solar cells drops by about 20% compared to the catalog specifications at 25°C. Each manufacturer is also making efforts to address this problem, and Panasonic's HIT solar cells combined with heat-resistant amorphous solar cells, and Solar Partners' compound-based CIS solar cells are about 5%, suppressing the output drop due to heat. I'm doing it. Image Source: The temperature on the roof in midsummer is 60 to 80℃, so the amount of electricity generated in midsummer is not very large. Looking at the annual power generation transition graph, you can see that the power generation is increasing in May, which is cooler than the midsummer of July and August. Image Source:Areas with low temperatures and long hours of sunshine are advantageous, but if snow falls and piles up on the solar cells, it will not be able to generate electricity. Therefore, areas with low temperatures and long hours of sunshine that don't snow (very little) are suitable for solar power generation.
Areas suitable for solar power generationIs the area you are considering installation suitable for solar power generation? Please check the estimated power generation by region announced by each manufacturer.
As you saw above, the power generation efficiency varies depending on the location, but the "angle" and "orientation" of the roof also have a large effect. This is a big problem when installing in existing buildings such as renovations.
South facing roofs are suitable for installing solar panels. In general, installation on the roof on the north side is not recommended because the power generation efficiency is low and there is also the effect of light pollution on the neighbor's house. Even if you want to install solar power generation, you can't get enough power unless you allocate a lot of area to the south.Image Quote: Also, solar panels cannot generate electricity efficiently unless they are installed at a suitable slope. According to Panasonic, the difference in the amount of power generation is as follows depending on the slope.
Power generation by slope (Panasonic survey)| Roof slope | Estimated annual power generation |
|---|---|
| 3 dimension gradient (approximately 16.7 degrees) | 5,653 kWh |
| 4 dimension gradient (approximately 21.8 degrees) | 5,722kWh |
| 5 inch gradient (about 26.6 degrees) | 5,750kWh |
| 6 inch gradient (approximately 30.9 degrees) | 5,760 kWh |
| 7 dimension gradient (approximately 34.8 degrees) | 5,731 kWh | < /tr>
Annual average of optimal tilt angle for each year (in the case of due south)
| Region name | Optimal slope (annual average) | Corresponding slope |
|---|---|---|
| Sapporo City | 34.8 degrees | 7-inch slope (about 34.8 degrees) |
| Sendai City | 34.5 degrees | 7 sun gradient (about 34.8 degrees) |
| Shizuoka City | 33.3 degrees | 6.5 gradient (approximately 33 degrees) |
| 23 wards of Tokyo | 32.8 degrees | 6.5 Dimensional gradient (approximately 33 degrees) |
| Nagoya City | 32.5 degrees | 6.5 dimensional gradient (approximately 33 degrees) |
| Yokohama City | 32.5 degrees | 6.5 degrees (about 33 degrees) |
| Matsumoto City | 32.5 degrees | 6.5 degree gradient (about 33 degrees) |
| Hiroshima City | 29.8 degrees | 6 inch gradient (about 30.9 degrees) |
| Osaka City | 29.2 degrees | 5.5 Dimensional gradient (approximately 28.8 degrees) |
| Matsuyama City | 28.5 degrees | 5.5 dimensional gradient (approximately 28.8 degrees) |
| Kagoshima City | 27.7 degrees | 5 dimension gradient (about 26.6 degrees) |
| Fukuoka City | 26.1 degrees | 5-slope (about 26.6 degrees) |
| Kanazawa City | 25.7 degrees | 5 degree gradient (about 26.6 degrees) |
| Niigata City | 25.0 degrees | 4.5 Slope (about 24.2 degrees) |
| Naha City | 17.6 degrees | 3 Slope (about 16.7 degrees) |
In addition, if the slope is gentle, it tends to collect dust and snow.
As we have seen above, solar power generation efficiency will decrease if it is not installed at an angle suitable for the south side.
This is a concern when considering solar power as an investment. As long as it is powered by sunlight, the amount of power generated will decrease if it rains for a long time.
Influence of weather when the amount of power generated in fine weather is assumed to be 100%Enechange editorial department investigation
As mentioned above, the amount of electricity generated during cloudy or rainy days drops to 50% to 10%. According to the Ministry of Economy, Trade and Industry, the annual power generation of a photovoltaic power generation system is calculated as about 13% of the installed capacity (capacity when power is continuously generated under 100% conditions). In other words, you think that the nationwide average will be 13%, including the weather. Another disadvantage of solar power generation is the instability of the amount of power generation, which is affected by the weather.
There is a word "maintenance-free" in the sales slogan of solar power generation. But the truth is, the technology isn't that mature yet.
Certainly, the solar panel itself has an extremely simple structure that does not use a motor, so it does not break easily. In fact, it is not well understood how long solar cells will deteriorate or break down, and it seems that the number of expected lifetime of about 10 to 20 years, which is the warranty period, does not have much basis. However, even if the panel itself does not deteriorate much, failure due to improper construction or failure of the power conditioner that uses the motor can occur normally. According to the Procurement Price Calculation Committee, which determines the purchase price of photovoltaic power generation, the annual operation and maintenance costs for fiscal 2016 are 3,200 yen/kW for residential use and 6,000 yen/kW for industrial use. If a 4 kW facility is installed, the maintenance cost for 20 years will be 256,000 yen. See 4kW installation simulation for details. Currently, most manufacturers provide panels and power conditioners with an output warranty of 10 years or more, but that means that a warranty is necessary. Solar power is never maintenance free.
Solar Power and Money
Now you know what solar is all about, right? Now let's start talking about money.
On February 22, 2016, the committee approved the chairman's proposal for the procurement price and procurement period for fiscal 2016. After this, approval from the Minister of Economy, Trade and Industry is still required, but it can be said that the decision has been made. Based on that, the following table shows the transition of the purchase price so far.
Changes in purchase prices| FY2012 | FY2013 | FY2014 | FY2015 | FY2016 (planned) | |
|---|---|---|---|---|---|
| Residential solar power generation (less than 10kW) | 42 yen/kWh | 38 yen/kWh | 37 yen/kWh | 33 yen/kWh35 yen (with control) | 31 yen/kWh 33 yen (control compatible) |
| Non-residential solar power generation (10kW or more) | 40 yen/kWh | 36 yen/kWh | 32 yen/kWh | 29 yen/kWh27 yen (from July) | 24 yen/kWh |
Please see the fixed purchase price column for 2015. Two prices are displayed, and (control compatible) is written at the bottom. This is because after the Kyuden shock, it became mandatory for some electric power companies to install machines that control the amount of power generated by photovoltaic power generation (equipment that supports output control).
Electric power companies that require output control devicesIn areas other than Tokyo, Kansai, and Chubu Electric Power, it is necessary to install output control devices in the photovoltaic power generation system. The cost is about 10,000 yen per kW. The role of the output control device is to suppress the voltage rise (power generation) during peak hours. During sunny days and other times, the output of photovoltaic power generation is so high that it may exceed the capacity of the electric power company. To prevent this from happening, the power company will operate each solar power generation system to prevent it from generating electricity. If the voltage is suppressed, power generation will not occur within that time, so the purchase price is set high.
Details on voltage suppression are summarized here. If you live in an area that requires an output control device, please check it out.
What is the mechanism of sending electricity by selling electricity and voltage suppression that reduces the amount of electricity sold? What is the countermeasure?
Now, let's take a look at a specific simulation!
What are the benefits of solar power generation?
It is the sum of the two. Daytime is the time when the sun is out, from 7-8 in the morning to 5-6 in the evening. During this period, solar power generation will generate electricity, so the electricity bill that was incurred before installation will not be charged. The profit of solar power generation is the sum of the amount of electricity sold and the surplus electricity sold. It is solar power generation as an investment product that recovers the initial investment with this profit, and after that it becomes a profit. Let's take one example.
A family of four installed a 4kW photovoltaic system on a south-facing roof for 1.41 million yen. If installed facing south, it will generate an average of 1100 kWh per 1 kW per year, so this solar power generation will be 1,100 x 4 = 4,400 kWh. The amount of electricity used last year was 4500kwh and the electricity bill was 121,500 yen. Assuming that the amount of electricity used during the daytime is 30% of the total, the amount used is 1350kwh, and the annual electricity bill is 36,450 yen. In other words, the annual power sales amount is 4,400-1,350, which is 3,050 kWh. Electricity charges are calculated at 27 yen/kwh (estimated unit price for 2014 electricity charges)The following is a simulation of living in areas covered by Tokyo, Kansai, and Chubu Electric Power where there is no obligation to install an output control device.
10-year annual recovery amountSince the purchase price guarantee under the FIT system for residential solar power generation is 10 years, the purchase price after that is still undecided. However, according to the January 2016 announcement by the Agency for Natural Resources and Energy, “Concerning the status of the introduction of renewable energy and the review of the feed-in tariff system,” the expected situation in the future is that the benefits of selling electricity after the purchase period will be reduced to wholesale electricity. Since we are proposing to assume the market price of 11 yen, we will calculate the purchase price after the FIT period ends as 11 yen.
Annual collection amount after 10 years. If you make a graph of this, it will look like the following.
4kW introduction simulation (2016 version)The unit of the vertical axis is 10,000 yen. The investment will be recovered in the 12th year, and the surface profit after 20 years will be 600,000 yen. This is a superficial income simulation derived from the amount of power generation. Operation and maintenance costs such as equipment failure and inspection costs will be deducted from this.
Estimated operating and maintenance costsPower conditioners usually come with a 10 to 15-year warranty, and some vendors offer free inspections, so how much does it cost to operate and maintain? I can't say for certain. However, the operation and maintenance cost, which the Procurement Price Calculation Committee has heard from manufacturers, is 3,200 yen per kW per year as the market average. Based on this figure, the operation and maintenance cost of operating a 4kW solar power generation system for 20 years is 3,200 x 4 x 20 = 256,000 yen. If you take a paid regular checkup every 4 years for 20,000 yen and replace the 200,000 yen power conditioner at your own expense, the balance after 20 years will be 344,000 yen.
If you install a 4kW photovoltaic power generation system for 20 years, you can see that you can recover the original cost and earn an income of 600,000 to 350,000 yen. So, with the purchase price going down, how does it compare to before 2016?
It is said that the purchase price has fallen and the solar bubble has burst, but in reality, the profit margin has not changed significantly in residential solar power generation. This is because as the purchase price goes down, the equipment price goes down in parallel. See the table below.
Simulation of 4kW installation from 2012 to 2016
| FY2016 | FY2015 | FY2014 | FY2013 | FY2012 | |
|---|---|---|---|---|---|
| Purchase price | 31 yen | 33 yen | td>¥37 | ¥38 | ¥42 |
| Annual recovery amount (10 years) | ¥131,000 | ¥137,100 | ¥149,300 | ¥152,350 | ¥164,550 | Equipment cost | 1.41 million yen | 1.5 million yen | 1.54 million yen | 1.66 million yen | 1.86 million yen |
| Yield (FIT 10 years) | 9.3% | 9.1% | 10% | 9.2% | 8.8% |
| Payback years | 11 years 6 months | td>11 years 10 months | 10 years 9 months | 12 years | 13 years 1 month |
| 20 year gross profit | ¥600,000 | ¥571,000 | ¥653,000 | ¥563,500 | 485,500 yen |
You can see that there is almost no difference in the yield and the number of years to recover. The solar bubble has burst! Prices keep dropping! This is a word we often hear, but there has been little change for residential use with a capacity of 10 kW or less.
The three-year period from July 2012, when the FIT was launched, was considered a profit consideration period, and the profits of solar power producers were guaranteed. As a result, investment in solar power generation was concentrated, and solar power generation facilities were constructed all over Japan. Now, how will the purchase price of 2016 change the investment value of industrial solar power generation of 10 kW or more?
The actual amount of solar power generation currently in operation is about 27 GW, but the certified amount (about 82 GW) has already exceeded the target for 2030 (about 64 GW). Based on the "new certification system" scheduled to be implemented from 2017, the government plans to eliminate projects that have only been certified and are not operating, and to achieve the operation target for 2030. However, as of FY2016, there is no prospect of how many non-operating projects (staying projects) will be eliminated. It was decided. The purchase price for industrial use in fiscal 2016 was 24 yen/kWh, a 40% decrease from just after the start of the FIT system.
This is a proposal for those of you who are planning to install solar power generation!
You should now have a pretty good idea of what solar power is all about. So here's a suggestion for our readers!
Similar to Mr. A's opinion at the beginning, this article basically recommends installing solar power generation for ordinary households.
Although it depends on the shape of the roof and the area where it is installed, solar power generation is something that recovers the original capital and makes a stable profit even after recovery. The joy of using environmentally friendly energy and being able to use electricity independently is irreplaceable. If you have a budget for a new building, you should install it, and if you have an existing house, I would like you to consider installing it when you renovate it as part of your asset management.
I saw a simulation of 4 kW earlier, but let's look at a simulation of 3 to 5 kW, which is mainly for residential use in Japan, as a guideline for how much to introduce.
Simulation by installation amount| Installation amount | 5kW | 4kW | 3kW |
|---|---|---|---|
| Equipment cost | 1.75 million yen | 1.4 million yen | 1.05 million yen | < /tr>
| 1 year monetary benefit (FIT 10 years) | ¥165,100 | ¥131,000 | ¥96,900 | < /tr>
| 1 year monetary benefit (after 10 years) | 82,100 yen | 70,000 yen | 57,900 yen |
| Payback period | 11 years and 3 months | 11 years and 6 months | 11 years and 4 months | < /tr>
| Total profit after 20 years | ¥722,000 | ¥600,000 | ¥498,000 |
Also, even if you want to install solar power generation, there are some points to consider in the case of an existing building.
Precautions for existing housesThe storage battery plays an important role in the zero energy house ZEH. Some manufacturers such as Panasonic also sell creation-storage collaboration systems that combine storage batteries and solar power generation. Let's take a look at the pros and cons of batteries.
Advantages of solar + storage battery Disadvantages of solar + storage batteryThe biggest advantage of installing a storage battery is that you can use the electricity you make yourself without any waste. With solar power generation alone, surplus electricity had to be sold to electric power companies, and at night there was no choice but to purchase electricity as before. Therefore, even if there is a power outage due to a disaster, etc., electricity can only be used during the day when the sun is out and generating electricity. However, by installing a storage battery, it will be possible to aim for self-sufficiency in electricity.
The profit consideration period has ended, but in fiscal 2016, we are maintaining a purchase level that allows us to expect a certain amount of profit. However, that will most likely be until 2016.
It depends on the status of the elimination of non-operating projects, but if 40 to 50 GW conforms to the new certification system as expected, in FY 2017 the purchase price determination method will be a bidding method or a top runner method (top runner = the most efficient A method based on excellent equipment) will be introduced, and the purchase price may be in the 10 yen range! In any case, the existing method of determining the purchase price will end in 2016, so if you are thinking of installing a new solar power generation facility, we recommend that you install it during 2016.
How to choose a contractor for solar power generation construction
Flow of solar power generation construction
Well, you can read up to this point and think about solar power generation Kana, you who thought! Let's take a look at the actual deployment path.
Let's take a closer look at the flow of introducing solar power generation.
It would be a good idea to get a free estimate on the bulk estimate site I introduced earlier. If you send a quote request by entering simple details such as the shape of the roof on the Internet, the person in charge of the bulk estimate site will call you and consult. All five of the above companies are very kind to help, so please feel free to ask them anything you don't understand. Please don't forget to consult with them as soon as you have any questions in the future.
Three to five local sales companies introduced by the estimate site will come to the site for a site survey (sometimes we will make a rough estimate based on drawings before doing so).
Good things to be prepared forSometimes the other side will explain it to you, but in many cases it won't, so let's ask about the following points.
Good points to askIt will be finished in about 45 minutes to 1 hour and a half. Please treat the contractor while thinking about whether you can continue to associate with them for the next 20 years or more.
First of all, the quote doesn't really contain much information. This is because each company has its own style of writing, and the classification items are also different. Therefore, what is more important than the details is to check the price of the quotation, the power generation simulation, and whether the after-sales follow-up is appropriate. For that reason, competitive estimates are essential, so be sure to get estimates from multiple companies.
Easy checkpointWhen you sign a contract, please check the construction schedule carefully. To apply for the subsidy, you will need to prepare a certificate of residence and seal certificate, and go through the procedures together with the contractor. Please check the Panasonic page for easy-to-understand subsidies nationwide. Check subsidies for photovoltaic power generation systems/Panasonic
The construction will start about a month after the contract is signed, and will basically be completed in a day. There is also electrical work in the room, so it is necessary to accompany someone, and at the end it is necessary to turn off the breaker once. The important thing on the day is not to check the construction work, but to entertain the craftsmen by serving them tea, which is nice and easy. It is said that many of the problems that occur in construction are not due to lack of skills, but are mostly psychological. A simple consideration is fine, so please make sure that the craftsman can work comfortably.
Although it is not provided as standard, it is recommended to get a diagram (layout diagram) of the actual solar panel connections that are connected on site. This is because the drawings at the time of the estimate based on the field survey and the original specifications may have been changed due to the local response. It will be an important drawing for maintenance, so please provide it.
After the construction, we will install a power meter and ask the power company to come and connect it. If you are unlucky, the "construction date", "electricity meter installation date", and "connection date" may be different, but everything will be completed in about two months from the contract. When connected, the electricity sales meter starts to rotate, and the memory of the amount of power generation increases steadily. You are now the manager of a solar power plant. Let's start the power generation life by properly checking the daily power generation amount!
Methods for maintenance of solar power generation equipment
Solar power generation is finished after installation! That's not what it means. It's always exposed to the elements, so you never know what kind of problem might occur. Let's take a look at the daily checkpoints so that you can be alert immediately if something goes wrong.
If dirt and dust accumulate, the amount of power generated by solar power generation will decrease. It is a good idea to check the appearance once a month.
Consistently check for any dirty spots, scratches or cracks. However, it is dangerous to actually climb the roof and check it, so it is not recommended. I think it's just a matter of checking whether there are any abnormalities that stand out from a distance. Therefore, the daily check that is actually necessary is to check the amount of power generation.
Even if the solar panel itself does not deteriorate much, the connection part and power conditioner may deteriorate and affect the amount of power generation. However, since it depends on the weather, changes in the amount of power generated can only be seen on a yearly basis, not a weekly or monthly basis. Manufacturers and dealers each provide various power generation data collection tools, so please take advantage of them.
If you think something is wrong, contact the vendor or the person in charge of the estimate site you used. In that case, if you can tell us the specific reduction in the amount of power generation, the response will be smoother.
This article summarizes the necessity and method of maintenance in detail. Isn't that funny? If you think so, please see this article.
How to maintain power generation? Photovoltaic system maintenance
Summary of solar power generation
What is a solar cell? I have seen the whole picture of solar power generation from the beginning to the actual introduction in a hurry. I hope this gave you some idea of what solar power is. Solar power generation is absolutely indispensable for ecology and energy saving. Please consider adopting it positively!Lastly, let's summarize what is important.
Absolutely Important Things to KnowBy installing a solar power system, electricity will not be sent from somewhere far away, but will be generated by our own hands. As the situation surrounding energy changes day by day, including the full liberalization of the electricity retail market, it is very important to be able to proactively respond to energy in order not to lose money. Solar power generation will surely open the door to the future energy-saving society for you.