Battery Storage for Solar PV
How it works
‘Energy storage’ lets you store the surplus solar electricity, instead of exporting it. Battery storage lets you use more of your solar PV system’s output (in the jargon, it ‘increases ‘self-consumption’). This reduces the amount of grid electricity you need to buy, saving you money on your electricity bill.
During the day
- The solar PV system generates solar electricity
- The battery storage system will check if all the generation is being used to power your lights and appliances
- If you’re not using all the electricity that the solar PV system is generating, then the system will ensure that any surplus energy is used to charge the battery
- Once the battery is fully charged, if there is still more solar electricity being generated, this will be exported to the grid (or in some systems, will be diverted to other uses e.g. to an immersion heater)
In the evening or at time of low solar generation
- The solar PV panels have a reduced or zero output
- The battery system can discharge the stored electricity, providing you with renewable-generated electricity at no additional cost
- Once the battery is discharged, if you need to use more electricity, you buy it from your electricity supplier
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Despite expectations, some storage systems will not provide power during a power-cut. Some battery storage systems however do have an ‘off-grid’ functionality, providing a limited amount of power to your home, or to essential equipment (such as your fridge-freezer, lighting etc). But a battery may run out of power before the power cut ends – or have already run out of power if it’s been discharging all evening and the power outage starts late at night or early in the morning. If you require your battery storage system to provide power during power-cuts it is important to talk this through with your storage installer from the outset as the system will need to be carefully designed and set-up to your specific requirements.
Does it affect my Feed In Tariff (FIT)?
The generation FIT is paid for every kWh generated by your solar PV system, as measured by your solar generation meter. In addition, the scheme estimates (or ‘deems’) that half of this will be exported back to the grid and pays an export tariff on that ‘deemed’ 50%.
Your generation payment is unaffected in any way by the installation of your battery storage system. The solar electricity that is used on site or that goes to charge the batteries is registered by the generation meter at the time it is generated regardless of whether it is used onsite or sent to your battery storage system.
Your export payment is currently paid on a ‘deemed’ 50% of your solar PV system’s output, regardless of how much electricity you actually export or store.
Your FIT export tariff income will be unaffected if you store, rather than export, surplus solar electricity.