Are these options realistic? (aka 'Rate My Solar Plan' :) )

Pile_o_stone

If I were you I would forgo the battery just now and instead use the money to put the additional 6 panels on the SWW facing roof as it will generate electricity for you at the end of the day when the sun is at a more acute angle to the SSE panels. You'll increase the duration you're generating a useable amount of energy. At our house, a big chunk of electricity is used in the early evening as we prepare the evening meal (we have all electrical cooking).

We have panels on an East/West configuration and we avoid the massive generation at lunch time that we can't possibly use and extend the solar day as the sunrise hits the east panels and sunset hits the west ones. If you have the space for additional panels, I'd always prioritise more panels for energy generation over batteries for energy storage, especially given that solar panels last 25 years or more.

Boffinboy24

In case it’s helpful, we have a 5.6kWp system, SSE. We have a similarly high baseload of around 450w - large house, Wi-Fi APs, servers, security system etc. we work from home most days, and try and run washing etc during sunny periods. Since January when we had the system installed we have used 47% of what we have generated. It naturally varies by month due to the amount being produced - in January it was 55%, in June 45%. We have airco which we used a fair bit in July, so that came back up to 47%.

The point around orientation is a useful one - we tend to get sun fast and early in the morning, and it trails off fast in the evening. If I could have panels picking up sun in that period it would be very valuable. So much so I’d even consider non south facing almost!

I am on a fix until September and then plan to switch to Octopus to use their Agile outgoing. When I ran the numbers using agile it made it very hard for battery to stack up. Even without agile outgoing it was marginal benefit over the lifetime. All that said, I still regret not going for one when prices were lower at install! I am actually considering having one added with a couple of extra panels to save VAT. Why? Mostly because I like the idea of it, and even if it doesn’t deliver a return I would be OK with that, I like tinkering!

Alnat1

There is definitely a great satisfaction when the house runs overnight on sunshine. If a price could be put on that feeling, could it be calculated in as a ROI?

2nd_time_buyer

Alnat1 said:

There is definitely a great satisfaction when the house runs overnight on sunshine. If a price could be put on that feeling, could it be calculated in as a ROI?

My dad's proudest moment was during the powecuts after the storm in 1987. He hooked up the black and white TV to some lead-acid batteries he had stockpiled for such an eventuality. All the neighbors came round to watch TV.

Screwdriva

Alnat1 said:

There is definitely a great satisfaction when the house runs overnight on sunshine. If a price could be put on that feeling, could it be calculated in as a ROI?

For us, that great feeling was always negated by the country of manufacture, topped up by the reality that I would be adding to the supply issues with Lithium for EVs, where more carbon could be reduced.

2nd_time_buyer said:

My dad's proudest moment was during the powecuts after the storm in 1987. He hooked up the black and white TV to some lead-acid batteries he had stockpiled for such an eventuality. All the neighbors came round to watch TV.

I miss tubular lead acid batteries. Took up loads of space but they lasted 10 years without issue and cost a few hundred quid. 

Brimble

Thanks for the further comments. To reply to those above:

@94JDH - thanks for the link to the FB group, I've not yet come across the particular post you mentioned, but I have spent several hours reading through other posts, and found it incredibly useful. It hadn't occurred to me to try FB, but that as silly, as obviously there was going to be a huge FB group with lots of discussion - great.

@silverwhistle - no plans to get an EV tbh - I haven't driven for about 15 years, was a great relief giving it up actually. And yes there is an overwhelming number of variables to consider, and that's just the financial side - I've only just realised from reading posts in the last week or so that what I want to do / have should also be relevant, even if it's not the best solution financially.

@Magnitio - thanks for taking the time to address my individual questions. Yes our base load does seem rather high. We have one big fridge / freezer, a chest freezer, security alarm, security cameras, as well as all the obvious (internet etc) but it still seems high. I've been trying to turn things on and off and see how it impacts - will do more of that when I have more time, but already at times I've been able to reduce the base load to under 0.4kw (still high but better than it was). The fridge freezer is erratic - it increases the load by maybe 0.15-0.20kw from time to time, when it's 'buzzing' (i.e. presumably cooling). But thanks for the nudge to start with the basics.   Given your comments on my optimistic usage, I might amend my spreadsheet accordingly.

@pile-o-stone - hmmm, I tried running the calcs through my spreadsheet with extra panels instead of the battery, but the benefits seem nowhere near as good. Perhaps my assumptions are flawed, or perhaps it's just different for each household. I actually ran several new scenarios of more panels, with or without battery (or bigger battery), and it seems my current plan is best for our house. I guess there is no point having more panels if most of the excess will not be used by me, that's the bottom line. I know there is currently a good export tariff (Agile Outgoing), but I don't want to rely on that always being the case. Also, with regard to batteries, I appreciate your point about lifespan being so much less than panels (it's a really good point actually when comparing the two), but I am expecting - rightly or wrongly - that when I do come to replace the battery in 10+ years, it will be a damn sight cheaper than batteries are right now.

@Boffinboy24 - those are encouraging usage stats, good for you. Orientation is interesting to me too - my current plan is to have something like 16 x 400w panels together on my SSE-facing roof, but I could shift 6 of them onto a SW-facing roof if that would be a good idea. It is connected to the 'main' roof, but not easy to get at from my original planned panel location, so a couple of questions (for anyone, not just you! ) on that - if I want to 10 on one roof area and 6 on another:
 - will there be extra costs in terms of the installer presumably having to put up additional scaffolding?
 - will there be extra costs in terms of equipment, for example another inverter or whatever is needed?
 - will there be other complications?

With regard to Agile Outgoing, my attitude at the moment is to hedge my bets, i.e. get a battery while I can do so without paying VAT, make use of that tariff whilst it exists and is profitable, but know that I have a Plan B if that changes.

@Alnat1 / @2nd_time_buyer / @Screwdriva - it may well be Alnat1 who made me think the other day that it's not just all about ROI - I believe I will get some personal satisfaction from seeing my battery add day-to-day efficiency (even it's long term impact is arguable due to battery life etc) - having read lots of threads, it doesn't seem there is an obvious black & white answer on 'battery or no battery' - I guess as long as you've done your calcs and come to terms with the uncertainties in your assumptions, you pays your money and you takes your choice!


A couple of questions currently remaining unanswered if anyone wants to have a stab:

1. Does anyone know if prices tend to rise and fall in an annual cycle? (For example, extra demand from people getting excited late summer by all the sun they've seen, or people in Spring preparing for it, whilst people in Dec / Jan having other things to think about etc).

2. Are there certain features on batteries that I should look to include or exclude? The other day I was looking at LG Chem RESU-10H which is 9.8 kwh for about £5k for example...

3. (New question): Can I get an indication from DNO in advance of whether or not my plans are likely to be ok? Is there 'precedent' anywhere for each DNO? (NB. Current plan is 6.4kw panels, c.9-10kwh battery, probably c.5kw hybrid inverter)

Alnat1

1. Not really seasonal but recently very increased interest in solar due to high electricity prices and also because RE is the way to go. Installers are extremely busy and realising they can charge higher prices because of this demand. I contacted around a dozen in January, trying to get quotes and finally managed responses from 3 by the end of Feb. After accepting a quote I got lucky, an install date only 2 weeks ahead. From what I read on here install dates of 6-12 months ahead often being offered now.

2. Can only say what swayed my choice. I opted for a Lux hybrid inverter and pylontech batteries. The batteries are available as 2.4kWh and 3.5kWh and you can stack up to 8 on the inverter. I went with 2 x 2.4s with the thought that I can add more as/if required. It appears it's fairly simple to add more, something you can do yourself.

3. No experience, sorry.

Boffinboy24

Re: your question on multiple roof surfaces, I believe it can make a difference - mine was over two quite steep and high roof surfaces so multiple installers commented that quite a lot of scaffold was required. Mine was installed Jan 2022, so before everything went totally crazy price wise, and I still couldn’t get a particularly competitive price from anyone (at least compared to what people report on here - but at that time I wasn’t aware!). I think i ended up paying £1.3 per Wp. On the plus side because of the panels I wanted not being in stock I ended up with more expensive brand panels on the day because it would have cost the installer more to take the scaffold down and put it back up (I wasn’t willing to have it sitting up).

You should not need a different inverter, they will just put the panels on each orientation on their own “string”. Personally, if I was you, I would get panels on both surfaces and maximise the number on each. Obviously you need to check your maths, but if you can even manage a relatively small proportion of self usage, even without our currently huge electricity prices, then the breakeven will be faster than a battery and the lifetime is likely higher. If you can also add a battery it will be synergistic. I actually ran some numbers on a more north-facing set of panels on my property and it wasn’t totally crazy in terms of getting a benefit, though would generate essentially nothing in winter.

Screwdriva

Said another way, it’s your money so you decide how to spend it.

Personally, I would rather max my investment in Ripple energy’s project #3 for a 25 year reduction in my electricity bills vs. import a battery from China that does less good for the world. That said, I wouldn’t hesitate to splurge for one should the UK experience blackouts like some of the doom n gloom prophecies  predict. And it would be an LG chem battery!

But hey, that’s just me :-)

ispookie666

You (installer) would need to do the DNO paperwork, it is difficult to know which way the DNO will go. Alternate would be to limit the export to 3.68KWh there by becoming a G98 install.
If your neighborhood has multiple houses with solar panels, it is possible the network will be at limit for capacity. 
Any inverter/generator above 3.68Kwh will need G99.