When the Renewable Obligation Certificate (ROC) scheme closed in March 2017 to new applicants and solar PV installations, most generating stations in Northern Ireland did not have battery storage installed as part of their system. Additional cost at that time and hesitancy around an emerging technology meant that few installers offered this to their customers.
Fast forward 8 years and battery storage technology has advanced and become a popular addition to a solar PV system. Most installers will now recommend batteries to their customers as a way of getting the most out of their solar PV investment.
For domestic properties, 5kW and 10kW batteries are most typical. The main selling point and purpose is that they harness electricity generated from your solar panels when it is not needed inside the property and store this electricity to be used at a time when it is needed. Batteries are an effective way of running your property on green energy, even when the sun goes down.
When a customer has a battery installed with their PV system, many will ask what this means for their export electricity. Installation of a battery will lower the number of units you export back to the grid each year, simply because more excess generation is now being stored instead of being exported back to the grid. If your battery reaches full capacity, you will usually then export back to the grid (assuming you do not have another technology in your PV set up e.g. a hot water diverter).
A battery allows you to reduce your reliance on imported electricity from the grid and get more value from your generated energy than selling back to the grid. Import rates are based on the wholesale price of energy and therefore much lower than the value you can get from using it on site. Therefore, it makes financial and environmental sense to focus on using as much of your solar generated energy as possible.
In Northern Ireland, many solar customers will also try to maximise their battery use by switching NIE Networks meter types. Moving from a 24-hour meter to an Economy 7 provides different electricity rates at different times of the day. Economy 7 tariff is popular among electric car owners who choose to charge their car at night when electricity prices are lower. A battery can be used to charge your car at night using solar powered energy generated during the day.
Battery installation varies in price depending on size, manufacturer, and installer you choose to go with. Batteries are also more compact than a few years ago and are usually installed near your solar panel inverter. Typically, the lifespan of a lithium-ion solar battery is 10-12 years, which is about half as long as the lifespan of the solar panels on your roof. With most ROC accredited generating stations in Northern Ireland approaching ten years into the ROC scheme, maybe now is the time to think about an investment in battery storage that will prolong your savings past your ROC expiration date.
To summarise, if you have a solar PV system already installed and have not yet thought about investing in a battery, now is a good time to consider it.
Author: David Greer
References:
https://www.sunsave.energy/solar-panels-advice/batteries/lifespan