New Site DesignSolar Photovoltaic FAQ
What is solar photovoltaic (PV)? Solar photovoltaics uses semiconductor technology to produce electricity from sunlight. PV cells used in domestic systems typically consist of silicon wafers, a semiconductor material capable of generating DC electricity when exposed to light. These are connected together to form the familiar PV modules sometimes seen on house roofs.
How much energy can I get? PV works best when it is in full sunlight. The amount of electricity produced by a PV array depends on its exposure to sunlight and the characteristics of the cells and modules used in the array. For domestic applications, PV production can be expected to be anywhere between 700 and 850 kWh per kW peak (kWp) of installed capacity.
It should be noted that even minor shading can significantly reduce output, highlighting the importance of a site where shade is minimised.
Just like with batteries, when cells and/or modules are connected together, the cell with the lowest illumination dictates the current at which the rest of the series string operates at. This temporarily reduces the rating of the whole system until the shading is removed.
What happens to energy that is produced, but not needed? For grid connected systems, any excess energy can be sold to the national grid. You will need to contact your local Distribution Network Operator (DNO) for information on their buying and selling terms and conditions.
Does solar PV require maintenance? Solar PV has no mechanical (moving) components and therefore is silent in operation. This has the added bonus of there being no parts to wear out. Build up of dust on the modules does affect performance, but fortunately the wind and rain tends to remove this sufficiently well, preventing the need for regular maintenance.
What happens if there is a power outage on the grid? For grid connected PV systems, your system is automatically switched off within a few milliseconds of a power outage on the grid. This is to protect any electrical engineers working on the grid from being electrocuted as they carry out maintenance to restore the power supply. If you expect frequent power cuts, or cannot risk losing power at any moment you could consider battery or generator backup power supply.
What if I don`t want traditional modules on the roof? No problem. It is possible to use thin film PV (amorphous silicon) to create imaginative designs and to actually replace existing roof tiles. PV glass laminates can be used for transparent roof surfaces, such as to replace windows or the roof of a conservatory. These allow you to have a glass window and generate electricity at the same time. Contact us to find out more.
What lifetime can I expect from PV Manufacturer warranties tend to be 20 years for PV. The general lifetime of PV is defined as the time in years before maximum achievable output from the array has reduced to 80% of the original array nameplate rating. This reduction occurs as a result of gradual degradation with time. Once PV has reached its lifetime it will continue to operate, just at a reduced capacity. With no moving parts you can reasonably expect the array to continue operating for 40 years or more