Solar Electricity Application

The applications of grid-connected PV are wide-ranging. Grid-connected PV systems require very little maintenance. Using the electricity produced by the PV system directly in the building instead of purchasing electricity from the grid is referred to as offset. In some buildings, where the demand for electricity is steady during the day, there might be no surplus of electrical energy from the PV system , i.e. all of the electricity produced by the PV system is being used. This is important to consider when looking at the economics of a PV system. The way that electricity within the building is used must also be examined.

The lower the electricity demand in the dwelling, the greater the percentage of the electricity demand that can be provided by the PV system. Therefore it is important to try to reduce demand through behavioural changes and by using low energy / energy efficient appliances and lighting.

Stand-alone PV systems have the advantage that no grid-connection is required. The use of low energy and energy efficient appliances (including lighting) is crucial to realising the full benefits of a stand-alone PV system, as it ensures that the electricity demand of the building is as low as possible and therefore the PV system will supply a greater percentage of the electricity requirement.

As stand-alone PV systems can be used to produce electricity anywhere, the list of possible applications is not exhaustive.

• The developing world (schools, homes, hospitals)
• Telecommunications
• Where the cost of grid connection is prohibitive or impractical (e.g. in very remote areas not served by the grid)
• Water pumping
• Street fixtures (lights, bus shelter lighting, parking meters, road/street displays)

Designing stand-alone PV systems

The design and sizing of a stand-alone PV system is based around the following considerations :

• Feasibility assessment, including site survey and initial assessment of solar resource at site
• Assessing energy requirements including potential energy saving options.
• Economics : Payback time based on equivalent value of electricity that would otherwise need to be purchased.

For an initial idea of how much electricity a small domestic PV system is likely to provide, please see the Solar electricity benefits calculator.