Two batteries, one big dilemma

Last week we had a house battery installed by 4EVA Energy. House batteries are very popular at the moment due to the generous federal government rebates.

This is our second big battery. The first one we bought a couple of years ago. It was 51kWh and came with tyres, seats and a steering wheel. This is quite convenient, because we can drive the battery down to the shops and even take it on extended trips.  

It also comes with windows and a roof and an MG4 label on the front.  But this mobility can be a problem.  We often drive it away from the house during the day doing other things, so that it’s not plugged in to lap up the excess power from our solar panels.  Then we give away our solar power to the energy company at bargain basement prices.

Now, our new house battery is a stay-at-home, 24kWh battery, which is always on standby, ready to capture any electrons from our solar panels that look like they are going to sneak off to the grid.  

We had the battery installed a few days before that Saturday heat wave on January 10. By then, both the car battery and the house battery were chockers. Then came the overcast period. After a few days, the house battery was getting close to empty, and the car was less than half full, AND there was not that much solar power.  What to do?  

We could just buy power from the grid but that seemed like cheating.  So, we were faced with a dilemma.  

It is like having two children but not enough food for them both. Do we feed each of them a little and have them both go hungry or choose a favourite and let the other one wither. We chose the latter. Our new house battery got all the solar available.  Even with all the overcast and rainy days in the last 10 days, the house battery managed to scrape up enough solar to keep the house running without having to buy power from the grid.  

It just shows how much solar you get even on overcast days. All the power for the house was produced by our fairly modest 6.6kW solar panels.  That included power for hot water, cooking, refrigerator, all the usual electronic stuff, but not much air-conditioning.

Now the child (sorry, car battery) that was left to wither has enough charge for another 75km of driving at the time of writing.  However, I think we may need to buy actual grid power shortly!

It has been an interesting couple of weeks with the new house battery. We are pretty much over the idealistic phase, pretending that we are living completely off-grid.  I am now working on getting a better energy plan and allowing the system to run by itself without obsessive micro-management. 

I am sure there will be plenty to talk about by next month’s Flame magazine.