PV Install and battery storage.

[WillC]

Below is our quote that we're leaning towards going with. The intention is to have solar with backup power and the ability to load shift with Octopus Go. Any advice would be appreciated.

 

Can anyone see any issues? Is the equipment being installed ok? They're also going to add an automatic EPS switch for £1134.03. I'd never heard of Eurener or GivEnergy until I received this quote and both seem to have quite mixed reviews. Are people's experiences with this hardware generally good?

 

Are there any specific questions I should be asking or things I should be including? I'm fairly new to all this an the wealth of information out there is quite daunting!

 

[Thorfun]

seems reasonable to me. never heard of Eurener panels but I'm no expert. I would, however, get a couple of other quotes for comparison and then you can make an informed decision.

[Nick Thomas]

Weird that they've got 10x400W panels down as being 4.4kWp. Probably worth querying - or is that some magic effect of the optimisers?

 

Price-wise, it's pretty comparable to mine, taking my lack of optimisers, a cheapo inverter (wouldn't recommend) and a Solic S200 instead of a Genuine iBoost™©® (~£200 instead of ~£600). If you can export at 15p/kWh, a PV diverter isn't worth it, but you can't on Octopus Go, so might be worth getting one. You could ask them if they'd do the Solic instead to save an easy £400 - or get it done separately after.

 

If both the inverter and the iBoost are using CT clamps to decide whether to draw power (into the batteries and immersion heater, respectively) then I've read (but not seen - I've turned off the Solic now that export prices are 15p/kWh) that they can end up fighting over the same amount of power, leading to import happening as both pull the (say) 1kW available. Might be worth asking them about that specifically, or doing more research than I did on it.

 

I wasn't offered, and didn't think to ask about, bird proofing 🤔. I suppose an air rifle would be a bad idea.

 

 

I shared https://www.deegesolar.co.uk/eps_for_solar/ in another thread today RE: EPS - I was initially really excited about automatic whole-house backup, but decided the cost and effort wasn't worth it in the end. Mileage may vary, of course.

[WillC]

Quote

Weird that they've got 10x400W panels down as being 4.4kWp. Probably worth querying - or is that some magic effect of the optimisers?

I'll query it. The datasheet for the panels has two options, a 450Wp and a 460Wp, so it doesn't align with either of those either.

 

Quote

If both the inverter and the iBoost are using CT clamps to decide whether to draw power (into the batteries and immersion heater, respectively) then I've read (but not seen - I've turned off the Solic now that export prices are 15p/kWh) that they can end up fighting over the same amount of power, leading to import happening as both pull the (say) 1kW available. Might be worth asking them about that specifically, or doing more research than I did on it.

I was reading the iBoost now has an option where you can configure when it kicks in to prevent conflicts with the battery.

 

Quote

I shared https://www.deegesolar.co.uk/eps_for_solar/ in another thread today RE: EPS - I was initially really excited about automatic whole-house backup, but decided the cost and effort wasn't worth it in the end. Mileage may vary, of course.

I work from home and have a couple of machines that should ideally run 24/7, so it's mainly to keep those up and running. I once had a machine corrupted by a power cut, so it also reduces the risk of that happening.

 

Thanks for the helpful comments.

[JohnMo]

Am I working this out correctly?

 

Battery £4,826, plus install cost uplift £963 .  You have 1 cycle per day if overnight charging.  Warranty on battery is 10 years, but lets assume the battery is good for 20 years.

 

365*20 = 7300 cycles.

 

(4826+963)/7300 = £0.79, per cycle cost for battery/install.

 

Battery capacity can be fully drawn down, so 9.5kWh.  Normal cost £0.34/kWh, so £3.34 per day at normal cost electric.

 

Octopus Go night rate is £0.12/kWh, so 9.5kWh, so £1.14 per day at normal cost electric.

 

Additional standing charge on split rate tariff - Octopus 0.4952, compared to a normal £0.44302, so 5p.

 

Cost to have battery = Cost per cycle, plus standing charge = £0.79 + £0.05 = £0.84.

 

Saving on energy cost = Normal cost of 9.5kWh - Cost to charge battery - cost to have battery = 3.34-1.14-0.84 = £1.36 per day saving or about £500/year.  Without solar input and about a 11-12 year pay back.

 

Is there a risk the battery just cancels out the benefit of the solar or visa versa? Your day time usage could be circa 10kWh, provided by the battery and in the summer by the PV, but you may need to charge the battery every day to ensure you get full benefits.  

 

Am I missing something?

[Dave C]

You might not be missing something! I did the same calculation this year and ended up with similar results:

 

-Solar panels on their own: I couldn't self-use very much, so the payback period was not great

-Solar panels with batteries: Could then use vast majority of solar generation, but at additional cost, so payback period still not great

-Batteries on their own: Octopus Go meant I could still make good use of the batteries, and lower up front cost meant payback period was noticeably better

 

...so I went with batteries only (and if Octopus kicks me off/discontinues the Go plan, can always fit solar later).

 

Solar could make sense if you had different usage patterns to me - but yes, definitely worth doing the calculations as it can go either way.

[WillC]

1 hour ago, JohnMo said:

Am I missing something?

Financially, the investment is marginal. We do have an electric car, so we're already on Go for that, therefore the standing charge isn't exclusively for this setup.

 

I'm also working on the assumption that one day in the not too distant future, that national grid will fail to produce enough electricity and there will be blackouts, so with me and my wife working from home and a young family, a degree of energy independence certainly has a value, although not one that can be quantified.

 

Also, with costs rocketing, investments crashing, and a push towards electrification that's likely to push electricity costs up further, I thought I should take a gamble and diversify into something that isn't stocks/shares/savings/crypto/property. 

 

So, a financial gamble, but with diversification and a degree of energy independence on the scales, it tipped the balance in favour of investing in a solar/battery setup.

[Dillsue]

1 hour ago, WillC said:

I'm also working on the assumption that one day in the not too distant future, that national grid will fail to produce enough electricity and there will be blackouts, so with me and my wife working from home and a young family, a degree of energy independence certainly has a value

You might want to look into a small generator if your concerned about blackouts. Not seamless backup but will run for days if needed and way less than the cost of an EPS unit. A small genny is unlikely to power an ASHP, cooker or shower but it will keep the lights, telly, internet, microwave and CH running.

[SteamyTea]

3 hours ago, JohnMo said:

Am I missing something

VAT of the energy price?

[Marvin]

Inflation?

 

Is that including VAT?

 

Edited December 20, 2022 by Marvin
further thought

[WillC]

4 hours ago, Dillsue said:

You might want to look into a small generator if your concerned about blackouts. Not seamless backup but will run for days if needed and way less than the cost of an EPS unit. A small genny is unlikely to power an ASHP, cooker or shower but it will keep the lights, telly, internet, microwave and CH running.

A 3.6kw generator to match the output from the EPS would still cost in excess of £500, but has no auto switchover so my computers go down, it requires fuel, servicing and creates a lot of noise. £1134 for a silent and maintenance free system that *should* just work doesn't seem too bad in comparison.

[joe90]

I think it all depends on predicting outages, I don’t think we will get many (hopefully) and a small genny is always handy. 

[SteamyTea]

19 minutes ago, WillC said:

but has no auto switchover so my computers go down

If they are that important, you really should have a UPS fitted to them.

Built into laptops, unless like mine, it stopped working off battery power a while back.  Still, it is several years old so may treat myself to a new 'cheapest I can find' one.

[Nick Thomas]

If you've got a generator, you can twin it with a small battery and get uninterrupted supply that way. That's how datacentres generally work - a huge bank of batteries good for a few minutes, and a massive diesel genny out back that needs to fire up in the interim.

 

The victron inverters can take a genny as one of several inputs and do the necessary. It's a pain to keep the fuel around though, and if you don't have a big battery you can't fill it from solar, of course.

 

 

[Dillsue]

54 minutes ago, WillC said:

A 3.6kw generator to match the output from the EPS would still cost in excess of £500, but has no auto switchover so my computers go down, it requires fuel, servicing and creates a lot of noise. £1134 for a silent and maintenance free system that *should* just work doesn't seem too bad in comparison.

You don't need a genny that big to keep the basics running. We have a 1.5kva unit. It does require fuel but we have that already for the mower. If the genny is stored indoors it'll only need servicing every few years but give it an hour's loaded use at the beginning of winter and buy a Honda powered unit. We dont hear ours in the house when its running.

 

An EPS relies on a charged battery which in the winter will primarily be off the grid as youll not get much out of a 4kw array. If youre planning on off peak charging make sure you keep enough in the battery at the end of the day to keep you powered through an evening blackout.

 

I'm a bit biased towards genny back up as we had the power off for 3 days over Xmas in the 90s and have never been without a genny since