Orientation and mounting

Solar cells are typically assembles in a panel about one metre square. These panels should be mounted on a south facing roof at an angle of about 30º - this will maximise the solar capture in the summer, but will be non-optimum in the winter when there is less sunshine anyway.

A static converter called “inverter” is used to transform the direct current from the solar panels into an alternating current of the same voltage and frequency of the power from the national grid.

Grid connected systems

A grid-connected photovoltaic roof is simply a small electrical power plant installed as close as possible to where the electricity is needed. There is no need to store the electricity since any excess can be exported to the grid to be used in other dwellings. Electricity can therefore be bought and sold. This is local and non-polluting electricity production for your personal needs and those of the community.

A contract is signed with the local grid-operator company. A kWh meter records the amount of electrical current injected onto the grid so that this electricity can be invoiced to the utility.

Stand alone systems

If a dwelling is not connected to the national grid, then electricity needs to be stored when supply exceeds demand. Batteries are the common form of storage as these can store electricity for long periods of time.

The photovoltaic panels produce the electricity. The batteries store the electricity. The charge regulator controls the injection of current into the batteries to prevent them from overcharging and aging too quickly. The inverter transforms the batteries’ continuous current into alternating current (AC) if the household’s appliances and electronic devices use alternating current.

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