What exactly is the use of solar panels to supply electricity?
1. household electricity supply
A home solar power system uses solar panels installed on the roof to provide electricity for use in the home.
Installing a home system can reduce monthly electricity costs, and the following are typical figures for each installation.
・ Solar panel capacity
For example, a 5 kW solar panel system (approximately 15-20 panels) is typically installed.
・ Annual power generation
An average Japanese home can generate approximately 4,500 to 5,500 kWh of electricity per year (depending on region, weather, and installation location).
・ Reduction in annual electricity costs
If a household’s annual electricity consumption is approximately 4,000-5,000 kWh, a hypothetical 5 kW solar system would often reduce annual electricity costs by approximately 100,000-120,000 yen (assuming an electricity rate of approximately 25 yen per kWh).
・ Selling surplus electricity
Electricity that is not fully used at home (surplus electricity) can be sold to electric power companies, but prices have become lower in recent years.
*Price in 2024
◦ Less than 10kW (residential solar power generation): 16 yen/kWh (including tax)
◦ 10 to less than 50kW (industrial solar power generation): 10 yen/kWh (excluding tax)
◦ 50 to less than 250kW (industrial solar power generation): 9.2 yen/kWh (excluding tax)
However, these are the prices that apply under the FIT system, with a time limit of 10 years for less than 10kw and 20 years for more than 10kw to less than 250kw.
After 10 years of installing solar power generation, the power selling period ends, so the unit price of power sold generally tends to drop significantly.
２. off-grid system
Off-grid systems, which combine solar panels and storage batteries to supply electricity without connecting to the power grid, are used especially in rural and mountainous areas where power supply is difficult, and during disasters.
・ Solar panel capacity
For example, a small 1.5 kW photovoltaic system (approximately 5-6 panels).
・ Storage battery capacity
Storage batteries used in conjunction with solar power generation systems are generally 2kWh to 5kWh.
This makes it possible to supply electricity even during the night when solar power cannot be generated.
・ Daily power consumption
The average electricity consumption of a household using an off-grid system is about 3 to 5 kWh per day.
In this case, a 1.5 kW solar system can generate about 4 kWh of electricity per day, which can be stored in storage batteries and used at night.
3. Electricity supply for commercial facilities and companies
Increasingly, solar panels are being installed on the roofs of commercial facilities and businesses to meet their own electricity needs.
Solar power generation reduces the facility’s operating costs and environmental impact.
・ Solar panel capacity
For small to medium-sized commercial establishments (e.g., restaurants and retail stores), systems of 10 kW to 50 kW are often installed. Large scale facilities may install systems of 100 kW or more.
・ Annual power generation
A 10kW system can generate approximately 10,000-12,000kWh of electricity per year.
This translates to a reduction of approximately 250,000 to 300,000 yen in annual electricity costs (calculated at an electricity rate of 25 yen/kWh).
・ self-consumption rate
The self-consumption rate for commercial facilities and businesses indicates the percentage of electricity generated by solar power that is actually consumed by the company.
A self-consumption rate of 50% to 70% will result in a higher reduction in electricity costs.
4. EV (electric vehicle) charging
There are a growing number of cases where solar panels are used to charge electric vehicles (EVs) at home.
By using home-generated electricity to charge EVs rather than from the power grid, an eco-friendly car lifestyle without fossil fuels can be realized.
・ Solar panel capacity
For residential use, a 2kW-3kW solar panel can generate approximately 150-250kWh of electricity per month.
・ EV Charging Amount
The battery capacity of an electric vehicle (e.g., Nissan LEAF) is approximately 40 kWh to 60 kWh.
If a home solar power generation system generates more than 300 kWh of electricity per month, it can provide all the electricity needed to recharge the EV.
5. Electricity supply to remote areas
Systems combining solar panels and batteries are used to supply power in remote and disaster areas.
Even in areas without an electricity grid, basic power can be supplied using solar power.
・ Solar panel capacity
Typically, 2kW to 5kW solar panels are installed. This can generate up to 10 kWh or more during the day.
・ Storage battery capacity
Combined with 5kWh to 10kWh storage batteries, the power supply can be maintained at night and on cloudy days.
Solar panels are widely used in homes, businesses, and remote locations, and it is important to select the right size and capacity for each need.
A typical household can generate approximately 4,500 to 5,500 kWh per year, while commercial facilities often install systems of 10 kW or more, and solar panels can help reduce electricity costs and environmental impact.