Towards battery storage

For quite a long time, I have been thinking about adding battery storage to my set up; the recent eye-watering rise in the cost of grid-purchased electricity here in the UK is finally driving me from thinking about it to acting on it.

It is not a simple matter however; choices about battery size, whether to include grid outage back-up capability, where to physically locate the battery and charger/inverter, - all these and much more have to be worked through, and inevitably compromises identified and accepted.

I have persuaded myself that the case for battery storage is unassailable. My reasoning goes like this: my Powerspout is good at delivering energy over long periods at low power levels; batteries are good at delivering energy over short periods at high power levels; by combining the two, advantage can be taken of their respective strengths.

In effect, for a grid connected Powerspout like mine, a battery can be used to address the limited capability of the Powerspout to deliver sufficient power when domestic appliances like a kettle or cooker are turned on; the battery opens the door to saving on the energy which would, without a battery, be drawn from the grid.

In the complicated journey of working out how to configure a battery system, a major 'road block' has been how to integrate the existing diversion device I have, a Solarcache; it harvests surplus energy and diverts it to 3 different heating loads in the house, always maintaining a bare minimum of power to trickle back to the grid; it has been a very valuable component of our system which we have come to rely on as our sole source of domestic hot water in the summer months; I am keen not to have to jettison it with the introduction of battery storage.

The 'road block' was because my Solarcache was an early model which lacked the later firmware which enabled Solarcache to be adjusted so the battery management system (BMS) got first priority of surplus power; 

Happily, yesterday that block was removed; I discovered I had a spare Solarcache with the required firmware update; below is the screen from it which shows how the Solarcache's settings can be adjusted to give the BMS priority.

The settings allow for a threshold level of Watts flowing back to the grid, and a delay time during which that power needs to flow, before Solarcache will start to divert power to the loads connected to it. Discrimination between the settings of the BMS and Solarcache can thus be achieved to ensure the BMS gets first priority.

I was really excited at discovering I could keep Solarcache alongside the battery system; having removed that particular 'block', I now feel free to progress the battery scheme further.

I'll post more in due course.