Solar panels and battery - any real world reccomendations?

Ron-ski said:
@Andrew Moore Not only will it clip what the panels can produce, it will also limit how quickly you can charge the batteries from off peak in the winter - you may not be able to fully charge 20kwh of batteries during the off peak period. You need a bigger inverter which will require a G99 application.

PS. Also check the maximum charge rate of the batteries.
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I shouldn’t need to charge them fully, the max I have used between 4pm and 00:30 is 13.8kwh. If I factor that in, I’ll only need to charge at around 2kwh to keep 16+ in the battery. I’ll never go beyond what is produced during the day even in the winter on a 7.2kwh system and in the summer I’ll have more power and storage than I’ll ever likely use as I’ll not use the battery pack to charge the car I shouldn’t imagine as it’ll be on an 1-1.2kwh trickle during the day
 
@Andrew Moore Your choice of course, but for the sake of a few hundred quid more and a G99 application, I'd be looking at a bigger inverter. Even if you don't use the extra generated it will enable you to sell more back to the grid, peanuts now (unless on a decent Octopus tariff), but I think that may change with time.
 
If I can’t get the extra 3 panels on the roof which will be determined tomorrow then I’ll stick with what I have got space for. If I can get the extra 3 on there then I’ll look at the g99 over the g100 and inverter to match then at that point.

Looking at the costs, the saving on the 3 panels if they don’t fit would probably cover most of the additional cost so I may look at it either way then.

All things considered a 6-7.2kwh system with near 20kwh of storage for just over £16k is a bargain all things considered at present.
 
Andrew Moore said:
All things considered a 6-7.2kwh system with near 20kwh of storage for just over £16k is a bargain all things considered at present.
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It's the going rate, not a bargain. £7.7k (inc VAT) will buy you 2x 9.5kWh Giv batteries and a HY5.0 Gen2 inverter. That means you are paying £9k for the PV an the install etc. If you want to break it down further you can get 18x 420w (7.56kW) panels for under £3.5k (inc VAT), so £5.5k is the cost of the rest of the kit and installation. Also bear in mind these are prices with 20% of VAT on it, which you are not paying.

I'm not saying it is a bad deal, but it is not a bargain, and it is even less of a deal with a 3.6kW limited inverter, so you can't make use of all those panels properly. It'll be a great setup however, and I am sure it will last a long time.
 
That's my plan as well, our existing 4kw system produced just 71kWh last December, which was the worse month since installation in December 2015, November and January was twice that.
 
Ron-ski said:
That's my plan as well, our existing 4kw system produced just 71kWh last December, which was the worse month since installation in December 2015, November and January was twice that.
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That's still 71kWh you didn't have to pay for, and used cheaper electricity to top up the system (if you have batteries).
 
SoliD said:
Sorry meant for Andrew Moore.
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Freefaller called it.

20kwh is enough to keep the house running so long as I have the facility to charge it over night when it’s cheaper.

I’ll also be making the conscious effort to drive the car lees if I can help it.

If a 4kw system only produced 71kwh in dec then I’ll break 100kwh on a 6-7.2kw system which will be more than enough to keep the day to day going during the day.

The goal is to keep my bill below £150 a month come januarys shafting and to then lessen that as each months production improves.
 
But you've stated you use 13.8kwh in an 8 hour period of an evening, I was making a guess that between say 5am and 4pm you'd use that and potentially even more. even if this is supplemented by what you can get in your batteries overnight at the cheap rate and perhaps 2 kwh on a bad solar day you won't be able to keep them topped up above 16kwh during the overnight period with the inverter you have there.

Nevertheless you'll be able to save a chunk of money using the cheap electric I was just highlighting your maths may bee slightly out unless I've missed something you're not tell us.
 
Andrew Moore said:
20kwh is enough to keep the house running so long as I have the facility to charge it over night when it’s cheaper.
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The facility is both the cheap TOU tariff and your inverter to charge the pack.

Some feedback as to why the 3.6kW inverter is being used/supplied as opposed to the much better fit of a 5.0kW inverter. Is it because you/the installer is trying to avoid a G99 application, or is it a supply issue? It's just a bad design for little to no saving over the better component, and on a system that is designed to last 15-25 years seems like a pretty big issue.
 
Journey said:
The facility is both the cheap TOU tariff and your inverter to charge the pack.

Some feedback as to why the 3.6kW inverter is being used/supplied as opposed to the much better fit of a 5.0kW inverter. Is it because you/the installer is trying to avoid a G99 application, or is it a supply issue? It's just a bad design for little to no saving over the better component, and on a system that is designed to last 15-25 years seems like a pretty big issue.
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Just a quick question, without assumptions, is this array split over east/west or is it south only. If so, the 3.6 should be ok apart from a smaller potential peak midday?
 
I think (years ago) when inverter prices were much higher it would have been a consideration. As the guys have said while its a fresh 25yr investment your size should go as high as you can in case down the road you need more capacity. I dont think the cost of the 5kw or around that are much more.
 
94JDH said:
Just a quick question, without assumptions, is this array split over east/west or is it south only.
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No idea.

94JDH said:
If so, the 3.6 should be ok apart from a smaller potential peak midday?
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It's not just about the peak from solar, it is also about the charge rate of the batteries in in winter months, and also the output peaks from that 20kWh of batteries, the 3.6KW only does 16A (3600VA), so you'll end up drawing from the grid when you are hitting the packs harder for cooking (over/induction hob), or if you are moving to an electric heating system. Taking a 5kW inverter gives you 22.8A (5000VA) which is much less likely to draw from the grid when large loads are presented to it, so less/no grid draw, that and the cost is ~£200 difference.
 
Journey said:
No idea.



It's not just about the peak from solar, it is also about the charge rate of the batteries in in winter months, and also the output peaks from that 20kWh of batteries, the 3.6KW only does 16A (3600VA), so you'll end up drawing from the grid when you are hitting the packs harder for cooking (over/induction hob), or if you are moving to an electric heating system. Taking a 5kW inverter gives you 22.8A (5000VA) which is much less likely to draw from the grid when large loads are presented to it, so less/no grid draw, that and the cost is ~£200 difference.
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I thought both the 3.6 and 5.0 can only discharge a max 3600W from the batteries which if Winter and dark will be the limiting factor?
 
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tsinc80697 said:
Yikes some of those reviews are shocking! I’m struggling to find a company to get back to me with some info and a price and it seems quite a few on Trustpilot have some terrible reviews.
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People are more likely to air their problems than give praise which can cause a skew in review ratings.
 
94JDH said:
I thought both the 3.6 and 5.0 can only discharge a max 3600W from the batteries which if Winter and dark will be the limiting factor?
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Yes, that is correct but you are also stopping any solar being used, and it was bad wording on my part as I didn't mean just battery usage but solar as well in tandem, when the late spring/ early autumn means you are generating still at "dinner" time, so you are limited by the 3600w for a much longer period of the year. Even if you prioritise the PV first, battery second you are still limited so not making the most of what is there on offer. I hope this made more sense, I'm not feeling amazing today tbh. :(
 
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