There are often questions from those looking to install solar PV on their home regarding whether batteries are worthwhile.
I've often commented how important batteries are to get the best from any generation system but perhaps today I can show why.
It has been a reasonable day for solar generation and the batteries have taken excess power which would otherwise be ‘lost’ to the grid.
The image above shows how solar has mostly powered our usage and added around 50% charge to our battery storage (consisting of a bank with 14.4kw storage capacity).
At present, it is slightly overcast but there is still 725w being generated which covers the house requirements and continues to add to the battery storage.
If I wanted to boil a kettle at this point, the home requirements would jump to just under 3kW and so the solar PV would not be sufficient to cope. However as there is abundant power in the battery storage and the system can deliver around 3.6kw, we would not draw from the grid whereas without the batteries we would draw almost 2kW while the kettle was on.
This is the situation faced several times each day as loads are switched on, often surpassing solar generation at that point. Charge in the batteries supplement the requirements and reduce the need to use power from the grid.
The same will happen overnight as the sun goes down and without batteries, we would be using power from the grid at the tariff rate whereas our batteries today will cover our electric requirements throughout the night when we hope for another sunny day.
