Guidance for solar system please

ddi

I’ve just read @Screwdriva thread re largest set up for £28k and think I may be massively over quoted for my potential set up. Would you please advise?

Currently use around 14000 kWh per year. Proposal for 22x Aiko 550 panels with PW3 costing £26k installation (including scaffolding etc). I’m based in south east England near Guildford. It’s a slate roof. SE facing with 35’ pitch. No indoor space other than loft for batteries hence the outdoor PW3. 

Am I being ripped off? Thank you!

Screwdriva

I'm sorry to say that it appears you are being overcharged (quite significantly!)

For perspective, the installers I use to help other forum members would charge less than £14K for:

22 Eurener 500W bifacial panels +
Tesla PW3 + Gateway 2 (whole house backup)

Fully installed including bird netting, G99 and 10 year workmanship warranty. If they can fit more panels on your roof, it would be £250 per panel and I suspect they will if you ask them to (recommended). 

Aiko has been on the market for < 2 years & is not a brand I would recommend (no matter how hard installers try to sell them to you). The PW3 is the best performing battery for outdoor/ uninsulated applications. 

Hope this helps! 

Martyn1981

Ouch! That's a crazy price. Please, please, please shop around. Looks like a large PV system (and batt) would work very well for you financially. So it would be frustrating for all us PV fans to see you lose out or be disappointed due to a very high install cost spoiling the economics for you.

Probably doesn't work these days, due to high inflation this decade, but my rough rule was that you'd pay a bit more than £1k/kWp for small systems, probably about £1k/kWp for systems around 4kWp or 5kWp, and then less than £1k/kWp for larger systems.

The reason being that most costs don't increase proportionately, only the rails, fixings and panels, and they are the cheaper bits now. Double the scaffolding doesn't cost twice as much, larger inverters don't cost that much more, and whilst larger cables may cost more, the work of running the AC side through your house will be pretty much the same regardless, mostly labour.

Almost 3yrs ago my sister had a 10.3kWp system (3phase) installed for only a bit over £8k (but she already had scaffolding in place).

Recent inflation may have thrown my rule out (@srewdriva - do you have a new rough rule I can 'steal'?) but panels have gotten so cheap now, that that will help counter some of it.

Screwdriva

Martyn1981 said:

Recent inflation may have thrown my rule out (@srewdriva - do you have a new rough rule I can 'steal'?) but panels have gotten so cheap now, that that will help counter some of it.

Given that the vast majority of the systems I am helping with are Tesla PW3 based these days (it costs less to get a PW3 with 11/13.5kW than a SolarEdge 10/10 kW inverter/ battery system), the rule of thumb is try to get as close to 30 panels to achieve that £1K/ kWp ratio we all love, for top shelf kit.

30 panels + PW3 = ~£15K for a 15kWp system that cannot beaten on performance/ aftersales support/ app/ Intellgent Flux tariff etc. etc. 

I'm certain OP can save > 45% on their installation (and benefit from more ethical bifacial panel gains too!). 

ddi

Crikey!! Thank you. I’ve called so many installers and they’re really just wanting to push finance deals / renting panels. These guys I pay outright but it’s a crazy outlay. It’s twice what I’d anticipated. Do any of you have installer  recommendations please? 

Martyn1981

ddi said:

Crikey!! Thank you. I’ve called so many installers and they’re really just wanting to push finance deals / renting panels. These guys I pay outright but it’s a crazy outlay. It’s twice what I’d anticipated. Do any of you have installer  recommendations please? 

Can't help with installers, but best of luck.

But, as an aside, can I ask why your consumption is so high? Is it due to being a large property (as your roof space might suggest), or do you have leccy heating?

I'm only asking, as PV plus a battery opens up a lot of additional benefits that may not have worked before. Such as a cheap rate leccy supply, as the batts can reduce day rate use, and also allow for cheap rate during the daytime in winter by charging from the grid. Also, something that many of us have found work well with PV, is an A2A (air to air of Air con) unit for heating, as you can heat the house (again via batt(s)) during the day, with cheap rate leccy.

PV, batts, cheap rate, EV, and A2A, all work well together and the whole is significantly greater than the sum of the parts, as they can all lean on each other.

Screwdriva

ddi said:

Crikey!! Thank you. I’ve called so many installers and they’re really just wanting to push finance deals / renting panels. These guys I pay outright but it’s a crazy outlay. It’s twice what I’d anticipated. Do any of you have installer  recommendations please? 

Sad to share this is the reality of the Solar industry....and why I do what I do for others. Feel free to DM me and I will ensure you receive exactly what I've shared above. 

@Martyn1981 is correct - while Solar will help reduce your costs dramatically, you would be wise to investigate ways to cut consumption at the same time. 

ddi

Thank you!
it’s a large house with 3 teens & laundry constantly on the go. Everyone eating and cooking at different times. Even if I batch cook, it’s microwaved at differing times. Everyone showering daily. TVs etc all built in so everything is always on standby too. Plus a hot tub in summer! But strictly summer.  

Our hot water & heating is all gas but all our cooking is electric. 

ddi

I think having the battery will be useful to import cheaper night time electricity to use during day. We are on octopus general rate atm. A couple of us regularly work from home so consume a lot of energy in the daytime.

Is there a maximum you can import overnight to a PW3 please? 

We have a combo boiler so I’m assuming an iiboost isn’t worthwhile? 

I’m thinking of installing an ev charger as hoping to get electric car at some stage. I e heard ppl talk of a ‘dumb’ charger but what is this?

huge thanks for all your suggestions. I’m very very new to all this! 

ddi

@Screwdriva are bi facial panels worthwhile on a black slate tiled roof? 

Screwdriva

ddi said:

Is there a maximum you can import overnight to a PW3 please? 

The PW3 has a capacity of 13.5kW. 

We have a combo boiler so I’m assuming an iiboost isn’t worthwhile? 

No, solar diverters like Eddi and iboost are a poor investment in your use case. 

ddi said:

I’m thinking of installing an ev charger as hoping to get electric car at some stage. I e heard ppl talk of a ‘dumb’ charger but what is this?

It is generally much cheaper to get a Zappi EV charger (the Solar EV charger best on the market) installed at the time of your solar system installation. I'd ask for this to be added to your quote. 

ddi said:

@Screwdriva are bi facial panels worthwhile on a black slate tiled roof? 

Bifacial panels work best if you have the installers paint the invisible area behind the panel white,  but they do work on slate roof's as well. Here is a video highlighting this.