An increasing number of countries are investing in solar power to produce electricity locally and reduce greenhouse gas emissions. Germany and Japan, the two leading countries in this field, have rolled out massive programs to equip individual households in particular with "solar roofs", to increase demand and encourage cost reductions.
Many government authorities are offering various incentives to help develop this industry:
- subsidies on equipment purchases
- tax credit on equipment purchases
- low rate bank loans
- high prices for kWh sold back to the grid
Solar modules are being fitted on houses both in the city and in the country. The only criteria is a good direction for one slope of the roof (south-facing is best). From northern to southern Europe, a 1 kWp (8 m²) solar roof will generate between 800 and 1,400 kWhr per year.
In general, a solar roof is a solar power generator of between 10 and 40 m², fitted on a household roof, either above the roofing tiles, which is known as overlay (top two images below), or integrated into the roof (bottom two images).
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Residential Building Application Connected to the Grid
A PV generator works by converting the sun's rays directly into electricity. A standard generator is made up of a solar field, a metal bracket to hold the modules in place, a charge controller and a power storage system.
A solar roof is made up of solar panels, a bracket to attach them to the roof and an uninterruptible power supply (UPS), which converts the power supplied by the panels into a form suitable for the grid, alternating current of 50 Hz synchronized with the grid with a single-phase voltage of 230 V. A single-phase meter will be installed by the power distributor for the connection to the grid.
It is fairly easy to install a solar roof, but professional support is required due to the use of direct current.
Unlike freestanding PV systems, there is no need for a battery, as the user is connected to the grid. It is vital to provide a protective system to disconnect the main power for maintenance work. This protective system, which is often controlled by the UPS, monitors the main voltage and frequency. Should there be an accidental main power cut (e.g. storm), the installation is automatically disconnected and no power is provided. This type of installation cannot be completely freestanding.