Difference in Solar PV and Battery quotes

akh43

I am looking to get solar pv and battery and so far have had 2 quotes, not much in the prices, but different recommendations by them.  I have a 3rd quote in the pipeline, but only requested that today.

I live in a semi detatched SE facing with a slate roof in Manchester.  I do not have an electric car and no plans to get one, nor do I have plans for heat pump as I have a gas combi boiler and happy with that.  My electric usage last year was 2,699kwh.

First quote was for: £10,688 : 8 x Aiko 460W, Neostar 2S N-Type ABC, GivEnergy 3.6kW, 1 x Giv 5.12kWh G3, Mesh & Clip Barrier System.  Lots of other options within the quote if I want different brands/specs or capacity.  The recommendation was to put the inverter and battery in the loft the battery on gable end.  Not really anywhere else to put it as no garage and outbuilding too far away and no electrics there.

Second quote has recommended 10 Aiko in roof panels rather than the on roof for the previous quote and has also recommended a 9.2kwh battery over the 5.12kwh of the first quote. He has said no way should the inverter and battery should be in the loft due to heat and also fire risk and has sent me this as the reason why https://knowledge.bsigroup.com/products/electrical-installations-protection-against-fire-of-battery-energy-storage-systems-for-use-in-dwellings-specification

He said the inverter and battery would be best outside either on a wall high up near the panels or alternatively on a 5ft party garden wall with a canopy over them to protect from the snow.   Second provisional quote until they have visited is approx £900 cheaper so just under £10k, but this could change.

Hopefully the third quote might give me some clarification, but still trying to get my head around the differences of recommendations.

Any comments appreciated.

QrizB

Unless you want a battery for non-financial reasons (eg. in case of power cuts or the zombie apocalypse), I don't think there's any reason for you to choose one at this time. It's just going to increase your costs without really helping your savings.

Did either installer quote for a PV-only option?

A 4kWp PV-only system (8x 500-watt-ish panels) shouldn't really be costing you more than £5k, unless there's something really difficult about your installation.

See for example here for a quote on a much bigger system (22 panels and a Powerwall) for £14k, which isn't that much more than the prices you've been offered.

https://forums.moneysavingexpert.com/discussion/comment/81391796/#Comment_81391796

Or here for a 10-panel PV-only system for £5.5k:

https://forums.moneysavingexpert.com/discussion/comment/81392264/#Comment_81392264

akh43

QrizB said:

Unless you want a battery for non-financial reasons (eg. in case of power cuts or the zombie apocalypse), I don't think there's any reason for you to choose one at this time. It's just going to increase your costs without really helping your savings.

Did either installer quote for a PV-only option?

A 4kWp PV-only system (8x 500-watt-ish panels) shouldn't really be costing you more than £5k, unless there's something really difficult about your installation.

See for example here for a quote on a much bigger system (22 panels and a Powerwall) for £14k, which isn't that much more than the prices you've been offered.

https://forums.moneysavingexpert.com/discussion/comment/81391796/#Comment_81391796

Or here for a 10-panel PV-only system for £5.5k:

https://forums.moneysavingexpert.com/discussion/comment/81392264/#Comment_81392264

The first quote has a breakdown of £6k for the panels and inverter, £4,160 for the battery and £528 for the mesh & clip barrier system to stop the pigeons.

Will ask the second and third quoter to give a pv only and pv & battery quote to see what they quote 👍

Screwdriva

Agree 100% with QrizB. A non-DIY battery like GivEnergy will never pay for itself within warranty with an annual consumption as low as yours. 

I recommend installing as many bifacial panels on your roof as will fit and going with a quality inverter system like SolarEdge. ~£5.5K is what you should expect to pay for 10 X Eurener 500W bifacial panels + 5kW inverter. (£300 per additional 500W panel + optimizer if more will fit). Bird netting, G99 and 10 year workmanship warranty included.

Another plus is that the inverter can go in the loft without any concerns - SolarEdge is probably the safest PV only system on the market.

If I can help, feel free to DM me. Regardless, don't let any installer convince you of the need for a battery. 

QrizB

akh43 said:

The first quote has a breakdown of £6k for the panels and inverter, £4,160 for the battery and £528 for the mesh & clip barrier system to stop the pigeons.

£4160 for the battery.

The calculation that follows isn't entirely accurate but it will do for this purpose.

At current tariffs, with export at 15p/kWh and import at 25p/kWh, a battery will save you 10p/kWh for each kWh of solar that you store in it to use later.

So you'll need to cycle 41,600kWh through the battery in order to save enough to pay for it.

You're using 2,699kWh a year. If you could replace all of that with solar, and all of it had to be through the battery, it would still take (41600/2699) 15.4 years before you've saved enough to pay for the battery. A 15 year payback period isn't a sensible use of your money, IMHO.

In practits likely to be at least twice that, so 30 years before the battery pays for itself - and it's unlikely to last that long before needing to be replaced.

akh43

Thanks for all your comments they have given me something to think about. I was thinking having a battery would mean I would be almost self sufficient and would only feed a bit back to the grid that I couldn't use.  I never thought of doing it without a battery as thought the battery would save me money instead of getting a small amount feeding it back to the grid when I couldn't use it.  I am subscribed to one of the Octopus threads and was always reading about people feeding back to the grid when they could get more for it in peak times so thought a batter would be better than just PV panels.

I hadn't realised how much more the battery was costing until I looked at the breakdown for using on this thread.  From what I had seen elsewhere I was thinking it made sense to get a battery to store it for my use rather than feeding it back to the grid and also in the winter to top up the battery cheaply during the night and then use when not much was being generated by the panels.  Did I get that wrong?  

In the first quote it is giving 16 years for the price quoted to be recouped, which to be honest was longer than I expected.

I am at home a lot of the time as retired so will be using some of it during the day, but probably not that much as my daily usage is between 5.9kwh-8.9kwh when I checked March's use.

Any thoughts on in roof or on roof installation.  I have been told its more costly to fit on slate due to having to take more time to fit.

Screwdriva

akh43 said:

Any thoughts on in roof or on roof installation.  I have been told it's more costly to fit on slate due to having to take more time to fit.

I have a slate roof. It takes a day to fit 10 panels on roof in accordance with MCS guidelines. I would not cut into slate unless you had a strong aesthetic preference. Bifacial panel gains are almost entirely nullified when using in roof cassettes and in roof installations are slightly more expensive. 

With a 10 panel PV only system, your payback will be ~7 years (give or take) with current tariffs.

zxzxzx

Just to play devils advocate, and not disagreeing with what either @QrizB or @Screwdriva say regarding payback on batteries. 

If you want to put time and work into the process you can improve on income.

“At current tariffs, with export at 15p/kWh and import at 25p/kWh, a battery will save you 10p/kWh for each kWh of solar that you store in it to use later”

Across 2024 my import was about 10p/kWh  with 15p export which will shorten payback.

 On which subject, payback is not overly important to me, I wanted to reduce my paid for electricity and do a bit for the planet and my grandchildren and I had the money to spend.

Different folks, different strokes.

akh43

Third provisional quotes in as given 2 options.

Both quotes cheaper than first quote for same set up, only difference in panels are Hengdian Group DMEGC Magnetics 3.600 kW, which I saw on another thread classed as bargain basement panels, not sure if they are better or not that the Aiko from the other quotes. Also not quoted for bird protection as not mentioned during the call, but that would need to be added.  First quote is same as original except for panel type above, but much cheaper at £6,547 - big difference.  Second quote is for Solar Edge 10.3, 8 with the same DMEGC panels and a 9.7 battery at £8,900. 

I am wondering should I ask about different panels with 3rd quote and the others? 

I was hoping 3rd quote would make things clearer, but it hasn't.

I think I would like a battery so I could utilise when no solar being generated, but not sure which size would be best.

The last quote has said nothing about placement of inverter and battery. 

I spoke to them before the 2nd quote and at that time I was unaware of the issue of having them in the loft is that as much of an issue as 2nd quote says? First quote did mention putting an extra smoke alarm in the loft..

All seem to be quoting for GivEnergy, but been reading on another thread about issues with them and wonder if I should go for a different brand.

First and Third quote give 5 year guarantee for labour/work with the relevant guarantees for the various equipment. 

I got all 3 from Which Trusted Traders and checked out reviews in various places before contacting and all have NAPIT, MCS,RECC and 1st & 2nd a lot more, but no idea what they mean.  All quotes very detailed and to be honest don't understand what half of it means.

Never expected it to be so confusing so any further comments appreciated.

Screwdriva

zxzxzx said:

Just to play devils advocate, and not disagreeing with what either @QrizB or @Screwdriva say regarding payback on batteries. 

If you want to put time and work into the process you can improve on income.

“At current tariffs, with export at 15p/kWh and import at 25p/kWh, a battery will save you 10p/kWh for each kWh of solar that you store in it to use later”

Across 2024 my import was about 10p/kWh  with 15p export which will shorten payback.

 On which subject, payback is not overly important to me, I wanted to reduce my paid for electricity and do a bit for the planet and my grandchildren and I had the money to spend.

Different folks, different strokes.

I'll let @QrizB come back to you on his numbers but what I will say on the doing your bit for the planet bit is that perhaps scarce resources like Lithium Ion batteries are better offsetting more carbon in EVs than they do serving as a UK grid powered home's battery, especially in the crazy geopolitical world we find ourselves in. 

I do agree that they have a place in high consumption households or to provide relief from frequent power outages. Beyond that, batteries appears more of a sentiment driven indulgence. 

akh43 said:

DMEGC Magnetics 3.600 kW, which I saw on another thread classed as bargain basement panels, not sure if they are better or not that the Aiko from the other quotes.

DMEG and Aiko are both low end, cheap Chinese owned brands with relatively low track records. Generally speaking, Chinese panels brands have among the worst ethical track records in modern history. 

akh43 said:

I think I would like a battery so I could utilise when no solar being generated, but not sure which size would be best.

See above comments on battery. If you want it despite never paying you back the £ you spend on it, hey, it's your home and your money so your decision! 

greenbee

It's also worth checking the bird mesh system. My first installation (on the garage roof) had plastic clips which were fine until we had snow... For the second installation the installers (who I called to fix it) sensibly looked at a more robust option as they don't really want to be going up ladders to the main roof in winter in the snow if there's a problem. We haven't had much snow here in recent years, so it's not something they've had to think about. My installers are our regular electricians (who also do outsourced solar work for a number of other local firms, as well as Octopus), and have worked with us to come up with a solution that meets our needs. 

I have a myenergi Libby inverter/battery with an Eddi hot water diverter (I have an oil boiler), and had extremely good customer service from myenergi when the Eddi failed. They asked the installer to try a few things, sent a replacement quickly, and sent a different engineer to do the warranty swap - apparently this is their standard practice to ensure that the problem isn't an installation one). They then arranged collection of the failed unit for testing/assessment/disposal. I'm aware they're not the cheapest (and installers are frustrated by the lack of an installer app and ability to check things for their customers before passing them on to the manufacturer) but so far it's all working well and the experience has been good.