Adding batteries to existing solar system

Petriix

I'm paying under £4k for the same Givenergy kit (3kW AC coupled, 8.2kWh battery). Although I've been waiting for stock for 6 weeks. I recently switched to Octopus Go after getting British Gas to fit my smart meter. Still on deemed exports. An EV is now a requirement for Go.

Swan_Valley

Our 2 x 8.2kWh batteries & 3kW AC coupled inverter cost about £6k inc 5%VAT, when installed with our second solar PV system.

It is worth getting some extra PV panels, so that you qualify for the 5% VAT.

Pulpdiction

Yes, might have to leave it a few months.  How many panels did you have to get?

Swan_Valley

Pulpdiction said:

Yes, might have to leave it a few months.  How many panels did you have to get?

We actually got a full new system for our east facing roof, but could have got away with just adding a couple of panels in order to qualify for the 5% rate. If I recall, that is what someone else did on here when they added a battery. The cost of the 2 panels & inverter they got was roughly equivalent to how much they saved in not paying the extra VAT.

Exiled_Tyke

Swan_Valley said:

Pulpdiction said:

Yes, might have to leave it a few months.  How many panels did you have to get?

We actually got a full new system for our east facing roof, but could have got away with just adding a couple of panels in order to qualify for the 5% rate. If I recall, that is what someone else did on here when they added a battery. The cost of the 2 panels & inverter they got was roughly equivalent to how much they saved in not paying the extra VAT.

That may have been me?  Two panels with one  600w microinverter.  As it is also on a different orientation to the rest of the set-up it supplements very well.  

michaels

Exiled_Tyke said:

Swan_Valley said:

Pulpdiction said:

Yes, might have to leave it a few months.  How many panels did you have to get?

We actually got a full new system for our east facing roof, but could have got away with just adding a couple of panels in order to qualify for the 5% rate. If I recall, that is what someone else did on here when they added a battery. The cost of the 2 panels & inverter they got was roughly equivalent to how much they saved in not paying the extra VAT.

That may have been me?  Two panels with one  600w microinverter.  As it is also on a different orientation to the rest of the set-up it supplements very well.  

If you purchased the panels would you need to install them?!  I don't think we would be allowed to add to our current FIT earning array so would need another inverter etc which adds hardware and install costs.  Perhaps we could just replace an existing panel on the fit array simply to reduce the VAT on batteries.

One problem is the 'pay back' depends hugely on the future path of electricity prices and availability of tariffs with cheap overnight periods - right now our 8k pa usage would be a lot less if we could get it all out of an overnight rate of 10p rather than the new cap of 30p - £1600pa which would pay for batteries to support enough time shifting but hopefully this is a temporary situation.  WE do already have the option of the leaf and V2g but our 24kwh will only store about 10kwh with a top and bottom buffer so not enough especially as we actually use between 4 and 10+ kwh per day in driving.

Exiled_Tyke

I can't answer all of these but I'll do what I can. I believe for the VAT saving you need a new 'system' installed. Hence why I went with 2 stand alone panels  with a micro inverter and it's own meter. The meter is only used to check that the system is working.  Other than providing electricity to the battery or the house I don't get any other recompense.   

The battery itself I don't think even now will pay for itself.  It cost just over £3k (with the reduced VAT) and I reckon a cycle provides 5.5 kWh (taking into account useable and round-trip losses).   Now for the finger in the air estimates.   By the second half of this year a cycle provided by PV could save as much as 30p kWh.  Let's say there are 200 days a year when I can achieve this.    Let's also say the remaining days I get a cycle from night time leccy. I'll assume these save 10 p kWh over import. (I know there will be some overlap days).   So say total savings of around £330 pa if the projected rates come in and stay so high.  So I'm guessing payback is still around 9 years.    I"m not convinced it's a goer on purely financial grounds. 

Exiled_Tyke

Oh and I am still having to buy full price leccy as I need more than the storage I've got! 

Pulpdiction

Think the VAT position may have changed, unless you had a significant labour charge: https://solarenergyuk.org/resource/vat-on-solar-and-battery-storage/#:~:text=Until October 2019, VAT on,on VAT have since changed.&text=If installed as a standalone,subject to the 20% rate.

Verdigris

There has to be a minimum 40% labour content to get 5% VAT rate.