No. A battery can be installed without impacting your FiT payments, although there may be some technical aspects to consider in designing the system. It may be necessary to advise the DNO (District Network Operator) of the intention to add a battery.

This is the amount of stored capacity the battery is capable of providing. To protect the battery some systems will never fully discharge. For example, a battery with a 10kW nominal storage capacity might have an 80% depth of discharge, meaning that it will only ever supply 8kW. This is an important consideration when comparing battery systems.

The battery controller will only allow the battery to be charged at a maximum specified rate. If the solar panels are generating a surplus which exceeds the maximum charge rate, it will send the maximum to the battery and export the remainder to the grid. On the flip side, if called upon to discharge to satisfy a demand exceeding the maximum discharge rate, any shortfall will be drawn from the mains supply.

Batteries have a warranty linked to a number of charge/discharge cycles. Typically manufacturers quote a 10-year life or 10,000 cycles (full charge and discharge), whichever is the sooner.

Some systems will provide power to critical circuits during power outages but may require extra components to do so.

Practically, this is almost impossible in UK latitudes as it would require an exceptionally large system to allow full self-sufficiency during winter months.

This will depend on various factors including the size of the solar PV array and its’ alignment, the profile of household electricity demand and, therefore, how much surplus electricity will be available for storage.

For domestic properties, the general rule is that the battery should have a capacity sufficient to provide power overnight until the following morning when the PV system will start generating one again and recharge the battery. This is complicated by the seasonal variation in daylight hours and greater demand for electricity during the winter when generation is at its lowest.

When purchasing a battery system, it is important to understand that it is likely that during the summer the battery may be fully charged and never fully discharged due to long day length, whilst in winter the converse may happen.

The ability to charge batteries using off-peak electricity can also influence the decision to add a battery to a solar PV installation