Is solar and battery storage worth the cost?

[AdamMGEV]

So i'm moving house soon and wanted to get Solar and battery storage. But after looking at the cost and googling it people say it'll take something like 12-15 years to really get your money back in the UK (cheshire). So is it really worth the cost? If it breaks within 10 years I'll have to repair and replace aswell. Apart from the environmental benefits it seems a lot of money so unless you have a lot of spare cash is it worth it?

 

[Jomarkh]

Have you had any quotes? With the price of electricity hopefully it will take less than 10 years for payback

 

[BugEyed]

It all depends on what price you assume for peak rate electricity and the delta for off-peak. At the current price for new Go contracts it makes sense, but at the 2021 13.7p/5p it makes no sense.

 

[DiscoSi]

The expected payback on our system installed earlier this year was just over 6 years. That was based on January electricity pricing and our energy usage (I work from home). With the ongoing escalation in prices the payback period is potentially shortening - although anything could happen (and tariff availability may change).

I put together a spreadsheet of historic usage to help optimise the system size (so it wasn't overkill) and then could also feed different tariff scenarios into it to see what our potential saving and payback period might be based on different rates. The installer also put their own high level version of this together for me - the two came out with fairly similar figures.

 

[sticky99]

Some useful info here from Martin Lewis

https://www.moneysavingexpert.com/utilities/free-solar-panels/

 

[Hotlush]

A 10 year warranty (for example) doesn't mean it will break at 10 years + 1 day.
With most systems you can buy an extended warranty if it really is a concern.

 

[AdamMGEV]

The expected payback on our system installed earlier this year was just over 6 years. That was based on January electricity pricing and our energy usage (I work from home). With the ongoing escalation in prices the payback period is potentially shortening - although anything could happen (and tariff availability may change).

I put together a spreadsheet of historic usage to help optimise the system size (so it wasn't overkill) and then could also feed different tariff scenarios into it to see what our potential saving and payback period might be based on different rates. The installer also put their own high level version of this together for me - the two came out with fairly similar figures.

Do you have a battery aswell? I'd be keen to get that so I wasn't forced to use electric mostly during high summer days etc

 

[Hotlush]

Do you have a battery aswell? I'd be keen to get that so I wasn't forced to use electric mostly during high summer days etc

The battery would be more for winter when the PV isn't producing as much. During summer you should easily cover your base load during the day, unless you've got a ridiculously high usage.

 

[DiscoSi]

Do you have a battery aswell? I'd be keen to get that so I wasn't forced to use electric mostly during high summer days etc

Yes, we got solar and battery and also have a Zappi for charging the car.

Originally I just wanted the battery as it theoretically had a quicker pay back than the solar and we're not in our forever home - but there are several benefits for installing both at the same time including 0% VAT on the battery element (20% if done as a separate install).

In the summer months it means that almost all our home usage (excluding the car) is covered by the solar / battery. We've proactively charged the battery a couple of times overnight (Octopus Go) where we knew there wasn't going to be much sun. In the winter we'll fully charge the battery in the Go period. Solar will help to cover our baseload and the battery will hopefully see us through the day. At the moment around half of our car charging is coming from the solar.

I should add that it wasn't all about the payback - we wanted to try and be a bit more self sufficient, but the numbers stacked up so I managed to convince my wife it wasn't a completely crazy idea. The panels have a long warranty. The battery kit/inverter is shorter, but we expect to have moved by the time it falls out of warranty - and will use the experience to influence what we do on a future property.

 

[Quinn Bliss EV]

The battery is a great compliment to a PV system. But do shop around for battery/install costs. We seen a wide ±£1k range of quotes for our 5kWh system.

 

[AdamMGEV]

Any ideas how long these batteries will last being charged and depleated constantly?

 

[Robf]

Is there a control system package available that allows use of the V2L capabilities of the car into a house? It would need to supplement with grid if requirement exceeded the cars supply I assume?

 

[Quinn Bliss EV]

Batteries

Any ideas how long these batteries will last being charged and depleated constantly?

Like in EVs, domestic batteries never fully charge or deplete. Warranties extend to 10 years so the lifetime would be greater. For example GivEnergy states that "Battery expected lifetime is 15-20 years".

 

[BugEyed]

Is there a control system package available that allows use of the V2L capabilities of the car into a house? It would need to supplement with grid if requirement exceeded the cars supply I assume?

No, there's nothing commercially available. As it stands V2L on cars like MG, KIA and Hyundai are not capable of grid coupling as there's nothing to make them run in the same AC phase. So the most that they can do is power specific circuits that are separated from the grid, either permanently or with a changeover switch with a power interruption of 10+ seconds.
There's a standard in existence that many manufacturers have promised to implement that will grid tie the inverters, but there's no agreement yet on if and how they will be allowed to do so in the UK. VAG for example have promised to retrofit it to existing cars, but given their record I'm sceptical. Obviously there's no home hardware yet for this so don't believe the usual vapourware manufacturers who claim to have it.

 

[BugEyed]

Batteries

Like in EVs, domestic batteries never fully charge or deplete. Warranties extend to 10 years so the lifetime would be greater. For example GivEnergy states that "Battery expected lifetime is 15-20 years".

Nissan LEAF batteries came with an eight year 70% warranty which has proved very hard to claim against. There's lots of 10 year old cars on 50% original capacity or less. Lots of previous GivEnergy and Growatt battery storage devices have failed in less than five years without successful warranty claims. PylonTech 10 year 95% DoD warranty is very optimistic - maybe they have learnt from others mistakes.

 

[Quinn Bliss EV]

Nissan LEAF batteries came with an eight year 70% warranty which has proved very hard to claim against. There's lots of 10 year old cars on 50% original capacity or less. Lots of previous GivEnergy and Growatt battery storage devices have failed in less than five years without successful warranty claims. PylonTech 10 year 95% DoD warranty is very optimistic - maybe they have learnt from others mistakes.

Battery management systems have really improved since those original Leafs. Most EVs now with good BMS will see very little loss in capacity. Compared to EVs though the x10 smaller home batteries do get cycled more frequently.

The tech and the market is relatively new and is changing year on year, many are warranted for 10 years with unlimited cycles. I wonder is there any degradation data out there?