Solar Panel and Battery Quote Advice

cf83

Hi,

I'm hoping to get some advice on quotes I'm starting to receive for solar panels and battery storage.

For context, I'm replacing both my petrol cars with electric vehicles and the household electricity consumption is 3400kwh. This will obviously increase significantly when both cars appear.

The quote I have received so far is as follows:

12 x 455W Canadian Solar Panels 5.46kW in total

Solis 3.6kW Hybrid Inverter

2x Dyness DL5.0C, 5.12kWh Battery Storage 10.24kWh in total

£8995 in total

I can add a further battery for an additional £895.

Your views on the materials being used, price and value in that third battery would be greatly appreciated.

Also, is it typical to expect to pay 25% up front?

Many thanks

Chris

QrizB

Canadian Solar and Solis are both established names in the middle of the market in the UK. Dyness I've not heard of but the £895 price for 5kWh is about right.

Fitting a 3.6kW inverter to a 5.5kW system, however, is just your installer being lazy and not wanting to do the DNO paperwork (unless they've already made an application and know they won't be allowed any more than that). It'll limit your output and reduce the utility of your battery.

£9k for that collection of kit sounds reasonable.

How many miles per year, in total, do you expect the two cars to do? And how much of that do you expect to charge at home?

QrizB

Just to add - if you can run to £11k or so, @Screwdriva might be able to suggest a system with 500W Eurener panels and a Powerwall 3.

cf83

Thank you. I would expect both cars to do around 8-10k miles each and I'm expecting to always be charging them at home.

Do you think the third battery is worth pursuing?

Could you excuse my ignorance and explain what the issue is with that particular inverter? Is there likely to be a delay with a G99 application?

QrizB

Two cars doing 18k between them will be an extra 6000kWh per year. that's more than your PV system will provide so your net import is likely to increase to 4000kWh/yr or so.

Excluding EVs, you're currently using 9-10kWh/day on average. With that in mind I'm not sure the extra battery will be worth it; assuming you take an EV tariff, exporting surplus electricity during the day and then using the battery to cover the "peak rate" hours of darkness shouldn't really need more than 10kWh of storage. You should be able to charge your cars on cut price EV electricity for less than you earn with export (assuming the current pricing strategies continue).

If you did want extra battery capacity, the PW3 looks more attractive IMO.

QrizB

Sorry, missed the inverter question.

The 3.68kW G98 option means that, in good weather, your PV generation peak will be truncated. This might cost you 10-15% of annual output.

It also limits the charge & discharge rates of your batteries. This might be less of a problem but does mean that if eg. you need to charge your EV outside of the cheap rate period you'll have to either restrict the charging rate or pay for half of your electricity at peak rates.

A bigger inverter (or the PW3) will avoid both of these drawbacks. The extra cost of a bigger inverter is tiny; looking at current prices, the 5kW is actually cheaper than the 3.6kW (and the 6kW is only £30 more).

https://www.bimblesolar.com/ongrid/hybrid-inverters/single-phase-hybrid-inverters/solis-hybrid

cf83

Thank you, I really appreciate you taking the time to respond. Should I push for a better inverter?

Screwdriva

cf83 said:

Should I push for a better inverter?

Sorry to share but I have serious longevity, aftersales support and ethical concerns about Canadian Solar (Canadian in name only) panels. See below for UK installer feedback.  Solis is another budget Chinese inverter brand - not one I would recommend unless installed at no cost via an ECO4 scheme. As @QrizB points out correctly, any installer should be applying for a 5+kW G99 export allowance via your DNO for your set up. Dodgy/ cowboy installers don't like the extra paperwork, and often try to con customers into settling for a G98 3.68kW allowance, which costs the customer alot in lost export over the life of the system. 

Eurener is a far more benign manufacturer - their panels are assembled in Valencia since 1997. 

12 X 500W black bifacial panels + Powerwall 3 will cost £11K installed, with bird netting and a 10 year workmanship warranty via installers I use to help other MSE forum members. Each additional panel costs £250 installed and I recommend installing as many as will fit on your roof. Feel free to DM me images of your roof and I can help guide you on this. 

Overall, I've seen enough to believe you can do much better than the quote/ installer shared above. 

 

cf83

Thanks Screwdriva. I'll send some images later if that's ok? It's a bit of a dog's dinner with different extensions. I don't suppose you know of anyone in Central Scotland doing that 11k PW deal?

Screwdriva

cf83 said:

I don't suppose you know of anyone in Central Scotland doing that 11k PW deal?

Sadly, no. I’ve heard Heatable can be good for Scotland, but believe it’s a whole different world for pricing. 

cf83

That's unfortunate. Do you think the Powerwall route is the one I should be pursuing, though?

I'm getting another price from a 'reputable' firm and they only use Duracell inverters and batteries. Thoughts?