Changing to Economy 7 meter for battery use

ejoyner

Thanks @QrizB - yes, and when you average the cost across 12 months for direct debit it's not much at all. Of course then I have to factor in the initial outlay...!

pensionpawn

I ordered a Powerwall back in Feb. In July I was told my October delivery date had slipped to April, at the earliest. Having analysed the benefit of a battery to exhaustion I can guarantee that they will be of maximum benefit around the eqinoxes and as useful as a chocolate teapot mid summer / winter. That's because besides offsetting nighttime use, in the summer you'll hardly use them and in the winter (besides timeshifting E7) you won't generate enough spare energy to store in them. Still getting one though.

ejoyner

Interesting @pensionpawn, my rudimentary estimates suggest a powerwall (13.5kwh) would cover 24hrs for us, apart from Jan-Feb. Only issue is the combined cost of ASHP+PV+Battery doesn't seem like an especially sound financial decision - only a sound emissions decision.

pensionpawn

ejoyner said:

Interesting @pensionpawn, my rudimentary estimates suggest a powerwall (13.5kwh) would cover 24hrs for us, apart from Jan-Feb. Only issue is the combined cost of ASHP+PV+Battery doesn't seem like an especially sound financial decision - only a sound emissions decision.

Look at how much you export Dec - Feb, import May - July inc. That's what the Powerwall can store for use later in the day. I have a 7.1 kW due east - west array and had 20 kWhrs (worth ~£6.60 at today's rate) spare in December. I would have saved 153 kWhrs (~£50) of import this June. The RoI for a battery is never likely to get any better than the present, however the RoI is still > 5 years (for me). 12 months ago the RoI was greater than the warranty period.

ejoyner

I wonder if any of you have investigated the various schemes and offers in place, obviously the government ASHP £5k one, but how about the utility company ones, e.g. solar/battery plans etc

QrizB

ejoyner said:

I wonder if any of you have investigated the various schemes and offers in place, obviously the government ASHP £5k one, but how about the utility company ones, e.g. solar/battery plans etc

The utility company schemes don't seem to be any better than the general market. It seems to me that the utilities are just serving to introduce their customers to their carefully-chosen subcontractors, rather than offering anything special.