Energy

Stand-alone power supply systems will most likely need batteries and may also need inverters.

Stand-alone renewable electricity generation systems that produce sufficient electricity for storage or that generate DC electricity must have batteries.

An inverter converts DC electricity to AC electricity and is required where electricity is a DC current such as from photovoltaic generation or where electricity has been stored in batteries, to convert the DC into AC. The inverter can supply AC current at any voltage or frequency by transformers, switches and control circuits.

Cables

DC electrical cable is generally thicker than AC cable, is more likely to overheat and can have large voltage and line losses if transferring electricity over distances. It is also more expensive.

Line losses may be reduced by:

• minimising the distance between the renewable electricity generator to the supply or battery storage
• increasing the voltage to reduce the current flow in the cable – DC output from the generator can be temporarily converted to high voltage DC for line transfer to the battery system
• transmitting electricity as AC rather than DC over long distances.