The more sunlight a house receives, the more suitable it is for producing solar energy. It is therefore important that the house does not stand in a shady place, such as between trees or tall buildings. Also, the slope of the roof should face south, southeast, or southwest.
The most important criterion in the construction of a solar power plant is its capacity. In order to maximize the profitability of the plant, it should at least be able to cover the on-site consumption needs as minimum. When calculating the power plant capacity, it is possible to rely on the average amount of electricity produced by Estonian solar power plants ─ approximately 1000 kWh per year from 1 kW power plant. So, if your house consumes 7800 kWh per year, you would need at least a 7.8 kW power plant. A larger plant may always be built. In that case, the electricity left over from own consumption can be sold back to the grid.
The solar power plant set includes solar panels, inverter, cables and mounting frames.
Elektrum cooperates with leading quality manufacturers. We have chosen solar panels from one of the world's leading panel manufacturers - Canadian Solar, for inverters we prefer ABB-Fimer, Kostal and Sungrow products. In the case of installation frames, we also prefer high-quality materials from European manufacturers.
Solar panels have a 10-year warranty against manufacturing defects and a 25-year warranty on 80% solar panel efficiency. The inverter has a 5-year warranty. A 2-year warranty applies to the installation work.
Two-way metering measures the electricity consumed and supplied to the grid. Electricity is taken from the grid only if the electricity produced is not enough to cover own consumption. The grid is supplied with excess energy from own consumption. The amounts of energy taken from the grid and delivered to the grid are measured by the network operator with which the producer has entered into a network contract.
Even on a cloudy day, a solar power plant still produces electricity, but less than on a sunny day.
Solar power plants do not require much maintenance. As the panels do not contain rotating or otherwise moving parts, the only regular maintenance required is to check that the solar modules are clean, free of dust or pollen, and not covered with leaves or snow. In practice it is rarely necessary. If the angle of inclination is greater than 10 degrees to the surface, the panels will be cleaned by rain. If solar panels are installed next to a building that is subject to a maintenance service agreement, the solar power plant is also included in the maintenance.
The profitability of a solar power plant depends on the exact equipment, the type of the roof, the angle of inclination and the electricity consumption. A properly selected solar power plant has a payback period of about 10-15 years and, with a subsidy, about 6-12 years. In general, the payback period is shorter for a more powerful power plant due to the lower installation cost per kilowatt (kW).
Renewable energy subsidy is paid for electricity produced in a grid or in direct line with a solar power plant of up to 50 kW. The rate of the subsidy is 5.37 s per kWh or 0.0537 euros per kilowatt-hour in addition to the regional price applicable for Estonia at the Nord Pool power exchange. The subsidy is paid for twelve years starting from the date the plant is connected to the network. In order to receive a subsidy, the solar power plant must be completed by the end of 2020 at the latest.
In winter, solar power plants produce less energy, as there are fewer sunny days and the days are shorter. At the same time, the cold winter weather promotes the work of solar panels making them more effective.
When building on a sloping roof - 1 kW takes an area up to 6 square meters.
When building on a flat roof - 1 kW takes an area at least 15 square meters.