Solar - what do I need to know?

cm4ever

Yes I'd 2nd that, definitely a fan of modular storage, in our case Uhome but many options available.

Netexporter

There's a new battery, coming in the next couple of months, which is going to shake things up, price wise:

Fogstar Energy 15.5kWh 48V Battery l Fogstar UK

Two of those and you could run a heat pump, all day, in the depths of winter.

zxzxzx

….devil’s advocate, buy all your kit from one supplier and you only have one to argue with if it goes pear shaped.

Read up because a 5.2 battery may not yield 5.2 of useable power. I have two but only a useable 9ish kWh.

Yes you can ‘pause’ battery output to save for when the grid price is higher.

yp70479

I got my kit in 2022, and at the time could only get 4p/kw for export. At that time it made sense to have a diverter, because it was cheaper  to use my excess solar to heat water (4p) rather than use the gas boiler (7p/kw). Now that what you can get for export exceeds the gas price it no longer makes sense and I hardly used it this year. I wouldn't bother with one if I was starting again now. 
Flux is a great tariff for the summer months (from about April to September). This year I stayed on it over the winter too, but I'm not sure I will do that again next year. I may well switch back to E7 paired with Octopus Agile export, which is what I used last year - there isn't much in it price wise, but I liked having the 7 hours of cheap electric and cos my battery (8.2kw) can cover my full day/evening consumption I never paid for any full price electricity. The 3 hours cheap charging for Flux may be pushing it if you flatten the larger battery during the evening.
If you are a bit of a tech wizz and into things like Home Assistant  then Octopus Agile can also be a good tariff, as it will pick the cheapest half hour slots to charge your battery.
I'm guessing the batteries you have been offered are GivEnergy. Just bear in mind that the usable capacity of a 5.2kw is about 4.2kw, but if we are talking about a GivEnergy 9.5kw then that has 100% capacity and you can use the full 9.5kw (this is because they basically have oversized the battery - its actually nearer to 12 kw, but only 80% of that is usable).
If your utility supplier permits I would also consider going onto a variable direct debit, because otherwise your direct debit will be based on your pre -solar usage and you will end up over paying. I'm with Octopus, and they let me do this right from the beginning. Over the summer my bills were zero and I paid them nothing - my export covered usage and standing charge for electric and gas. If you go with Octopus also look at their tracker tariff for gas - based on daily wholesale price. It can shoot up if the market changes suddenly, but all the time i've been on it  it has come in 1-2p/kw cheaper than the standard price.

EssexHebridean

Hi yp - thanks for that, some really useful info there! We're definitely not going down the diverter/water tank route - not least as the only place to put it would be in the loft and I am not voluntarily having water in my loft! 

It is the 9.5kw battery that we are looking at now - for many of the same reasons that you mention - it will cover all of our use much of the time, and only in the middle of winter when MrEH is working from home on cold days will we dip into grid use as a rule - as the home office is an outbuilding with electric UFH which as you can imagine whips through electricity rather! 

I probably wouldn't go the variable DD route at the moment I don't think - our DD is currently just £100 a month, and it is so simple to adjust it up and down with Octopus that I wouldn't be too worried about managing that aspect myself - it's been tweaked almost monthly since we've moved in and if we emerge from the winter with credit I'll be dropping it right down for a few months to get that used I think, as an easier option than getting it refunded.  Considering Tracker for gas is a decent idea though - it's something we were looking at as a possibility before we started seriously considering the solar and battery install anyway - it's just we wanted a full year in the house first to really ascertain how we thought things would work for us. It could be that going back to E7 electric could work well for us as well in fact - it's not like we're not used to it - it still feels very counter-intuitive running things like the dishwasher or washing machine in the middle of a day! I think it will need a proper comparison for pricing, and also finding out exactly how long the battery does need to fully charge.

Slinky

Tracker for gas is a no-brainer in my view. What would you rather pay 4p-ish or 7p per kwh? I even paid £75 to exit the fix I'd gone onto paying 6.78p when I realised my mistake. Saved that £75 in under 6 weeks and we're not high users of gas. We'll be paying a little more from next Thursday when our rates go up a bit, but it's still not getting close to SVT rates.  We are also on Tracker for electric which I will keep more of an eye on when it goes up next week, but coming into spring and summer, our solar should do the heavy lifting for a good while.

EssexHebridean

My only concerns with the tracker type tariffs are a degree of uncertainty - and that was the reason for originally wanting the year's worth of first use, as well as actually looking at the tracker pricing through a winter, before we committed. Right now we are also on a fix which will see us through to the start of next winter, but of course hopefully give it another few months and we will also be using very little of it, so... 

QrizB

EssexHebridean said:

... as well as actually looking at the tracker pricing through a winter, before we committed.

Winter 2022/23 Tracker was regularly bumping up against its 10p/kWh cap.

Winter 2023/24 Tracker was rarely above 5p/kWh.

"Past performance does not guarantee future results" as they say in all the financial ads.

(I stuck with it through both winters, fwiw.)

EssexHebridean

Thanks Qriz - It does seem like a bit of a no brainer, although I'd be interested to know how the upcoming price changes to Tracker are likely to affect things. Obviously it's not anything I'd looked at as yet as we're not in a position to make the jump at this stage. 

EssexHebridean

OK - I can now write a conclusion on this. We have now been through the process of survey visit, discussions on what is possible, and today have reached the decision that we're not able to go ahead at the moment, at least. The big issue for us is not having anywhere suitable indoors to house the battery and inverter. originally we understood that the inverter would probably go in the loft, with the batter on the external rear wall, but Octopus have now decided that they cannot site the two things apart like that. both could theoretically go outside, but there isn't sufficient room for the inverter and the canopy it would need for an outdoor installation - we have a 95cm drop from windowsill to ground, and the inverter needs 30cm of clearance all around meaning that there isn't enough height there. They were keen to fit the equipment to the front face of the house - but not only do we feel that this would be very at risk of theft or damage (it would be fully open to anyone just walking past on the street) it would also quite frankly look terrible - we are in an area with "open front" covenants meaning we would need permission to put it there in the first place, and we couldn't honestly see the LA giving that permission! 

It's disappointing - we've invested a fair amount of brain power in this over the past few months, only to now be told that it's a no. yet we live in a perfectly "normal" terraced house - and lots of folk in perfectly normal terraced houses seem to have these set-ups without issues...it makes me wonder if ours is really so problematic. Indeed, when the chap came to do the survey, he didn't mention ANY of the issues that have come up since, which also feels a bit strange!

One big takeaway I would mention to anyone else going with Octopus - when they first started discussing the possibility of putting the kit on the front of the house, I mentioned the restrictions and the need for permission we would face for that - and was immediately reassured that no, as long as we weren't in a conservation area, (we're not) we wouldn't need any permission. Now it so happens that we know our title quite well - partly as we've not long moved in of course - but it did occur to me that someone else might well be fooled into believing that was slid advice, and go ahead to make what could be a very costly error. I did response saying that they needed to be careful giving advice of that nature, and explaining why the advice was wrong - I got an apology back, but I suspect that this "advice" is probably quite routinely being given out... 

So for us, right now, it's the end of the journey. Our plan now is to stick it on the back burner for 12 months or so and then see if kit/sizes etc have changed, to make it more practical/possible. 

Thanks to all who contributed to the thread and offered help, suggestions and advice!