Adding a battery to our home started to make sense when electricity prices rocketed just as our electricity consumption dramatically increased due to our heat pump. We knew the battery would let us use more of the energy generated from our solar panels and allow us to use some cheap overnight electricity during the day in winter. So far it seems to be working – year to date we have used 88% of the power generated from solar – that’s 3.56 MWh compared to 40% (1.67 MWh) for full year 2021. Don’t have full year figures yet, the battery was only installed at the end of Feb 22 – expect another post when we do.
Why did we choose the Powerwall when it’s probably the most expensive system we could have bought?
- Big Company – any battery system is a big investment – we are pretty sure that Tesla will be around to honour their decent 10 year warranty. Necessary as payback is likely to be around 10 years!
- Honest quoted capacity – we had a few quotes for different battery systems, Tesla were one of the few that specified the useable capacity of the battery in the headlines – others had useable capacities (sometimes hidden in the small print) that were 10% or even 20% less than the headlines. Pretty poor marketing in our opinion
- Competitive price per kWh of storage – the Powerwall has a useable capacity of 13.5 kWh, larger than all the other quotes we received – the actual cost per kWh ended up being cheaper than some – only worth it if you are going to use all the storage – with the heat pump in winter we do
- 5kW output – the Powerwall can supply 5kW, that’s enough power for our entire house most of the time. We are not pulling in grid power because the battery runs out of steam
- Backup power for grid outages – important to us as we live in a village supplied by overhead wires and we get around 2 outages a year. Everything except the heat pump and the EV charge point keeps working during a power outage – even the solar panels work
Nine months on we remain happy with our choice. There’s more on the Powerwall in practice here: https://ourhomeelectric.co.uk/powerwall-storage-in-practice/– it generally works well but we’ve had to learn a few things.