After more thought and planning a solar battery decision has been made. I discussed this and the various options here.
After lots of quotes and possibilities we have gone with the Tesla Powerwall
Solar Battery Installer
We have ordered the Powerwall through Spirit Energy. We now await an installation date 6-8 weeks we’ve been advised.. (Update – 18 Sep – we have an installation date of 30 Oct and DNO permission.) (Update – 5 Oct – we have an installation date of 6 Oct)) We also have to get some extra work done with RCDs on a couple of house circuits to allow the backup capability to work for the whole house. (Update – 18 Sep – we have to have a new Consumer unit awaiting install and of course increase in costs) (Update 5 Oct – all completed) This is one of the key benefits of the Tesla – whole house backup. We won’t be off grid but hopefully a very low user. So low the daily standing charge rises for electricity (Power companies getting more money despite consumption price cap) we have seen are noticeable.
Another complication is the DNO permission. This is the Distributor Network Operator permission to install generation (the battery potentially sending power to the grid). We didn’t need DNO for our existing solar. This is a 3.5 kw/h system so doesn’t need full approval. The Powerwall can be installed at this level and software limited to 3.5 kw/h until permission comes through. (Update 5 Oct – all approved) The battery can supply 5kw/h or >16 amps which we want for EV charging. Spirit Energy blog on DNO. The battery has >13kw/h capacity or approx 4hrs of charging at pre-DNO rate.
In this case, our supplier will handle getting permission and Tesla will adjust rate after DNO comes through. As with most government things at the moment it will probably be New Year.
I’ll also add some more details to the main battery page including costs