Not sure how to progress or to ask correctly. Quotes for solar and(or not) battery

AboutUs

We used a tool on this site (not forum) to get some quotes in. On line with a phone call. Also tried our supplier. Quotes come in and vary too much and some pricy but after reading a few threads here, realise we need the local installer and a visit for on site survey. Probably forget those quotes out of hand.

And when I dig into some of the threads here I also see that below a certain annual usage batteries are not recommended, payback is not really the worry if a battery adds a small amount vs overall cost and versatility.

Octopus app has us at 2386kWh in 2025, around £60-70 a month, that includes running a portable air con in the heatwaves. EV arriving soon and charger already fitted and will be shifting rates when it arrives. No idea extra load but understand lower rates affect the dynamics of use. Roof has east and west facing sides, nothing shading us.

So, how do you know installers are good, also backup post install? Always wary of the check trades sites. Then warranties should the installer cease trading etc. I have two local firms out next week for a look and quotes. I have noted some of the makes of kit that are suggested as not fitted if there are options.

One thing I am waiting for is the possible grants that are suggested (clocked a story today, coming soon). We may qualify for one. T+C I expect may restrict who we can use I expect.

Reed_Richards

I also see that below a certain annual usage batteries are not recommended

That may be true in the general case but if you have an EV that can make a big difference. If you can sign-up for an EV tariff then you can charge your home battery overnight at the cheap EV rate, even in the middle of winter when you won't get much solar power. For example last month (April) I was able to shift 86% of my electricity consumption to the cheap rate by charging my 6.5 kWh battery overnight so as to see me through until I had enough solar power to charge up the battery again.

Screwdriva

https://forums.moneysavingexpert.com/discussion/comment/81999180#Comment_81999180

An EV tariff is doubled edged. If you have an EV, you can store all that cheap energy in a battery for use during the day OR you can schedule all household heavy appliances (even an immersion heater for those on 2025's Intelligent Go rates) to run during the EV charging window instead.

Perhaps more concerning - most EV tariffs have become decidedly less favourable since the War in Iran commenced, further reducing the appeal of a battery sadly.

This is why household consumption has yet to be eclipsed as the test of whether a battery makes sense. Historically, import above 4000 KWh per annum meant the battery made sense. Anything below that and it didn't. In OP's case, I don't see how they will ever recover the cost of a battery.

https://forums.moneysavingexpert.com/discussion/6668375/not-sure-how-to-progress-or-to-ask-correctly-quotes-for-solar-and-or-not-battery

I get the frustration. In my experience after speaking with dozens of them, 4 out of 5 installers are cowboys (if not more). This is why I always select installers to use based on the following criteria:

1) How long have they been trading? More than 7 years means they survived the industry crash that happened when FIT tariff ended and will likely survive the next one.

2) What brands are on offer? If your only options are low end brands from the far east like DMEG/ AIKO panels and Fox/ Sigenergy batteries, then I would walk away. Installers who reject the higher profit margins that these brands offer the installer in favour of quality/reliability (eg. Tesla) are rare but worth hunting down.

3) How long is their workmanship warranty? 10 years is the absolute minimum I would accept. Cowboy installers typically do not disclose this duration if lower, in the hopes that the customer remains oblivious. During this window, the installer is liable to return to your property to rectify all faults at their expense regardless of the manufacturer's warranty. This is not to be confused with MCS Certification/ HIES or RECC insurance backed guarantees etc. which are also must haves.

4) What do their Google/ Trustpilot Reviews tell you? In the absence of a direct word of mouth recommendation, this is the only way to gauge the installation experience from others. Beware that not everything is as it may appear here, which is why I rate this the lowest among the above selection criteria.

As long as you do not deviate from the above, you should be fine. Hope this helps clear the smog a bit.

Reed_Richards

Perhaps more concerning - most EV tariffs have become decidedly less favourable since the War in Iran commenced, further reducing the appeal of a battery sadly.

I'm not sure this is true. Unless you are a very light user of your EV and can load-shift little in your house to run over the cheap night hours then an EV tariff will work out cheaper than the SVT tariff. In which case anything you can load shift via the battery will save you about 20p per kWh on the overnight charge and 18p per kWh on stored solar. In the winter I can load shift the full usable capcity of my battery and a bit more, lets say 6 kWh. At the moment its about 2 kWh in the morning and another 6 kWh in the evening, lets say an average of 7 kW per day over the year, saving an average of 19p per kWh which works out at £485 per year based on my 6.5 kWh battery. If you could get a 6.5 kWh battery for £3000 that would pay for itself in under 7 years if installed as part of a solar PV system.

@Screwdriva, feel free to point out flaws in my calculation if you can find them. I'm assuming 10p per kWh at night, 30p per kWh day and 12p per kWh export.

QrizB

I'm assuming 10p per kWh at night, 30p per kWh day and 12p per kWh export.

My only quibble would be that you should be comparing your load-shifted electricity savings to the equivalent single-rate daytime tariff, which is closer to 25p/kWh.

Otherwise you'll find yourself arguing that a "10p off-peak, £1 peak" tariff is even more beneficial because of the increased savings you would make. Which is not really true.

So your 20p/18p saving is more like 15p/13p, your average saving is 14p and your annual saving is £357 not £485.

Screwdriva

@Reed_Richards I was about to reply but @QrizB said it better.

Just to add, there may be other reasons for acquiring the right battery. Whole house backup is important to some of the rural homeowners who experience regular blackouts, but no £3K battery will deliver this.

Things looked better for home storage when Octopus Intelligent Flux was factored into the mix but that is limited to a dozen battery brands and is yet to be relaunched as a tariff this summer (sadly). Lucky are the few who did not switch away from this tariff/ switched back before the war commenced. (I am hearing louder rumblings of Tesla launching its own version of Intelligent Flux soon)

If my own home imported 3X the power it currently does (1.6MWh p.a.), I would get a Tesla PW3 in a heartbeat. The only way I will be able to justify the spend is if/ when we switch over to an air source heat pump.

Reed_Richards

My only quibble would be that you should be comparing your load-shifted electricity savings to the equivalent single-rate daytime tariff, which is closer to 25p/kWh.

I don't agree, @QrizB. As I tried to indicate, if you have an EV then it is very unlikely that you would be better-off on a single-rate daytime tariff, whether or not you have solar panels and whether or not you have a home battery. Is this wrong?

AboutUs

Not ignoring you, all, thank you, reading. Busy as well get back later but one firm is freshly minted, but owner split from previous firm. They were selling Givenergy (?) but now will be another Sigenergy. I think the other are doing Fox. Tesla is off my list (please accept my choice).

Heck.

OK, are people allowed to recommend here?

QrizB

@Reed_Richards asks:

Is this wrong?

In my opinion (and I appreciate that not everyone will share it), if you want to use the EV tariff daytime rates for your battery comparison then you need to look at the system as a whole. By adding components and recalculating the cost at each stage you can get a better indication of whether any particular change is worthwhile.

I know you like to use this approach when discussing plug-in EV chargers vs. wallboxes, for example.

It just so happens that the OP's situation is similar to the one I've analysed in some detail in this post. In that example, adding a battery and shifting all daytime use to the 8p/kWh off-peak tariff worked out as saving an extra £275 a year vs. EV and PV but no battery.

Edit to add:

Looking at the sums, I think part of the reason we differ is that you're assuming the household can shift 7kWh/day through a domestic battery. That's 2555kWh/yr which is more than the household uses and which will be reduced further by direct-use of PV electricity. I've based my calcs on only being able to shift 1100kWh/yr.

QrizB

Tesla is off my list (please accept my choice).

You'll make some of the forum regulars sad, as Tesla do seem to have a best-in-class product.

They were selling Givenergy (?) but now will be another Sigenergy.

Givenergy went bust, sadly, and their products were giving problems before that. Sigenergy are relatively new to the UK market so are a bit of an unknown.

I think the other are doing Fox.

Fox have been around for a little while and I get the feeling they are mid-market(?).

OK, are people allowed to recommend here?

Yes.

Reed_Richards

Looking at the sums, I think part of the reason we differ is that you're assuming the household can shift 7kWh/day through a domestic battery. That's 2555kWh/yr which is more than the household uses and which will be reduced further by direct-use of PV electricity. I've based my calcs on only being able to shift 1100kWh/yr.

When we bought our bungalow in 2018 we had an oil boiler for heating and hot water, cooked with electricity, all our lights were low energy, we had no solar panels and my car ran on petrol. I looked at our energy consumption for November and it was 8.4 kWh per day. So I've always had a figure of about 8 kWh per day in my head as a base load That's 350 kWh per hour and that's one of the reasons I installed solar panels and a battery in 2019.