What Is a Solar Panel?
A solar panel is a panel-shaped battery with the ability to generate electricity by converting the sun’s light energy into electrical energy.
Solar panels are also called photovoltaic panels or photovoltaic modules. Solar panels range from small residential panels that are installed on the roof of a home to industrial solar arrays (a combination of multiple solar panels) for businesses and investors that use large areas of vacant land or mountainous terrain to generate large amounts of electricity.
Uses of Solar Panels
Solar panels are used to generate electricity to drive electrical equipment (consumption) or for some other benefit from the generation of electricity, including the sale (production) of electricity for commercial purposes.
Solar panels can be categorized into three main types, and the appropriate material and construction of solar panels should be selected according to the application and installation environment.
- Roof-integrated panels + storage batteries: In households with all-electric systems, electricity is generated and stored at night to reduce high electricity bills during the day.
- Solar cars, calculators, and mobile batteries: Solar panels are mounted on devices to generate electricity to power the devices.
Principle of Solar Panels
Solar panels generally extract power by using the photovoltaic effect, which occurs when the light energy of sunlight is irradiated onto the surface of the panel.
To increase the amount of power, multiple solar panels must be connected in series to provide voltage, and these panels must also be connected in parallel to provide current. Since the extracted power is direct current, a separate device called a power conditioner is required to convert it into AC power for actual home use.
There are several types of solar panel power generation principles.
There are “silicon-based” solar panels, which have been used for a long time and come in a variety of forms, “compound-based” solar panels, which are designed to reduce costs, and “organic-based” solar panels, which can be made thinner, more flexible, and have added value in terms of coloring.
1. Silicon-Based
Silicon-based solar panels are, as the term implies, made of silicon.
Silicon-based solar panels use silicon wafers as semiconductors, and electricity is generated by the photovoltaic effect when electrons absorb light energy. The photovoltaic effect is mainly realized by pn junction photodiodes.
Silicon-based materials are further subdivided by material and structure.
- Classification as materials: There are single-crystal silicon type, polycrystal silicon type, and amorphous silicon type.
Each type differs from the other: monocrystalline silicon type has high power generation efficiency, polycrystalline type is inexpensive, and amorphous silicon type is thin and light, but has relatively low power generation capacity. - Classification as a form: thin-film silicon type, multi-junction type, etc.
Thin-film silicon type has lower production costs by making the silicon layers thinner, and the multi-junction type has high conversion efficiency and excellent temperature characteristics by stacking different types of silicon layers, each of which has its own merits.
2. (Inorganic) Compound Type
Compound (inorganic) solar panels are made of inorganic compounds that can replace crystalline silicon.
They are composed of a combination of various inorganic compounds, such as CIS and GaAs, which use semiconductors. Like silicon-based panels, compound solar panels generate electricity through the photovoltaic effect using semiconductors.
3. Organic System
Organic systems are solar panels made of organic compounds instead of the silicon and inorganic compounds mentioned above. Although lifetime and conversion efficiency are issues, the added value of organic solar panels is that they are flexible, lightweight, and can be colored.
Organic solar panels use organic dyes to generate photovoltaic power. A titanium dioxide layer with dyes adsorbed between two electrodes is used to generate electricity by photoexcitation of electrons in the dyes.
Solar Panel Prices
More and more people are considering the installation of solar panels to bring solar power systems into their homes. At the same time, many are concerned about their price.
Installation costs include not only the cost of materials and labor, but also caulking materials and other overhead expenses. Therefore, assuming an installed capacity of 5.00 kW, the estimated installation price is around 1.45 million yen. This is calculated from data provided by the Ministry of Economy, Trade and Industry.
If you are concerned about the cost, please refer to the installation cost along with the monthly electricity bill, income from electricity sales, and maintenance fees. After securing the benefits, long-term planning is important.
Lifespan of Solar Panels
Solar panels are expected to last about 20 years, with the longest panels lasting about 30 years. When solar panels reach the end of their useful life, there is no alternative but to replace them.
In addition, since the panels are installed outdoors, deterioration over time is unavoidable. Depending on the degree of deterioration, the panels may become inefficient at generating electricity sooner than they reach the end of their useful life.
Therefore, frequent maintenance is essential for solar panels. In general, regular maintenance is recommended once every four years. If paid maintenance is required, the cost is approximately 100,000-200,000 yen per visit.
For those who intend to store or sell electricity for profit, it is important to extend the life of the system as much as possible so that it can supply power securely.
Solar Panels and Storage Batteries
Storage batteries are becoming popular in conjunction with the installation of solar panels for home use. A device for storing electricity is necessary for both use for private consumption and for selling electricity. For this reason, many people are considering the purchase of solar panels and storage batteries as a combined purchase.
As time goes on, more and more people are considering storage batteries for their consumption, as the Ministry of Economy, Trade and Industry has announced that the 10-year feed-in tariff period for electricity will end in 2019, and at the same time, a storage battery subsidy program has been announced. Another reason is that the demand for storage batteries as a disaster countermeasure has increased, largely due to news reports of large-scale power outages caused by natural disasters.