Solar panels and battery - any real world recommendations?

[Ron-ski]

@doodah aware you may do a loft conversation in five or so years time, but can you not get additional panels along that front north west roof?

Also strongly advise against electric underfloor heating, you'd be better off if possible installing wet underfloor heating. We installed electric underfloor heating in out kitchen 20 years ago, and the bathroom pretty sure we never used either.

Heatable is usually rather expensive.

 

[doodah]

@doodah aware you may do a loft conversation in five or so years time, but can you not get additional panels along that front north west roof?

Also strongly advise against electric underfloor heating, you'd be better off if possible installing wet underfloor heating. We installed electric underfloor heating in out kitchen 20 years ago, and the bathroom pretty sure we never used either.

Heatable is usually rather expensive.

Thanks. My wife thinks less than 5 years, I think it's likely to be a lot more (saving >£100k is no easy feat and if we have a child - it will take a lot longer). Most of our quotes so far haven't suggested the NW roof for panels. I think Skylar said something but I prioritised the South facing sides. May I ask why? Let's say we don't get electric underfloor heating - our panel generation is already exceeding our annual usage by some bit. Is it a case of go all on where possible for panels and generation?

Edit - would having 15-20 panels not impact the inverter/phases we need and DNO application?

 

[Journey]

That seems dirt cheap for the amount of battery! I've heard it's difficult to find an installer for these Fogstar batteries though?

Plenty of installers will happily assist if you find the right one, who cares about what you want not what they want. This is your system, not theirs if they don't want to help there are plenty out there who will. It's no different to any other 48v battery, other than putting the correct config on the inverter, and if an installer can't do that I don't want them anywhere near my solar electrics if they are a one trick pony/someone who can only follow a script with no critical thinking abilities.

 

[Ron-ski]

May I ask why? Let's say we don't get electric underfloor heating - our panel generation is already exceeding our annual usage by some bit. Is it a case of go all on where possible for panels and generation?

Currently you can get paid for export at 15p or even 16p per kWh, how long this will last no one knows, but now in the summer months you can export loads and build up reserve for the winter. In the winter we don't generate much so we use the reserve to cover our bills.

My gas and electric has been negative for over two and a half years. We had a ASHP fitted in April, so gas has gone, I also got an EV in January which is mainly charged at home, even when away most of the charging is done on Electroverse, so comes out of my Octopus electric bill, yet I'm about £1100 up this year. That will get eaten into in the winter, but I'll still be negative.

Wet underfloor heating will work very nicely with an ASHP.

 

[b0rn2sk8]

Thanks. My wife thinks less than 5 years, I think it's likely to be a lot more (saving >£100k is no easy feat and if we have a child - it will take a lot longer). Most of our quotes so far haven't suggested the NW roof for panels. I think Skylar said something but I prioritised the South facing sides. May I ask why? Let's say we don't get electric underfloor heating - our panel generation is already exceeding our annual usage by some bit. Is it a case of go all on where possible for panels and generation?

I agree fully with Ron on this, electric underfloor heating is trash and it should be the absolute last resort.

We’ve got electric underfloor heating in our hallway, kitchen and dining room which the previous owners installed. I’ve turned it on once and watching the meter ‘spin’ I quickly came to the conclusion it was going to cost a fortune.

Cost wise you are looking at 4x the price of gas or heat pump to heat a room.

If you are going to spend a bunch of money putting in electric heating, do a heat pump and/or proper wet UFH.

Don’t forget, you are only going to be using electric UFH in the winter, solar generation will not be covering it and there is a cost gap between export and peak rate import.

Edit - would having 15-20 panels not impact the inverter/phases we need and DNO application?

It might, it might not matter too much. As as many of your panels are sub optimal in terms of orientation and being in the U.K. your sustainable peak generation will only be 70-80% of the theoretical maximum. Most hybrid inverters can be ‘over panelled’ by 150% some will take 200% of their capacity in solar panels.

With a hybrid inverter, you can charge the battery and export to the grid at the same time so even if you are hitting up against a DNO limit, you’ll still be able to generate the electricity.

Putting panels on the NW roof will be cheaper to install than the detached garage. You might need a second inverter but the garage can be covered by a small string inverter or micro inverters. That will probably be cheaper to install than running DC cable back to the house anyway.

You don’t need 3 phase that’s for sure.

 

[b0rn2sk8]

Plenty of installers will happily assist if you find the right one, who cares about what you want not what they want. This is your system, not theirs if they don't want to help there are plenty out there who will. It's no different to any other 48v battery, other than putting the correct config on the inverter, and if an installer can't do that I don't want them anywhere near my solar electrics if they are a one trick pony/someone who can only follow a script with no critical thinking abilities.

Not sure I agree, the list of MCS installers who would be willing to engage on such a job is tiny.

The vast majority of installers are looking to install a full system because it’s more profitable and there generally isn’t a shortage of work. It doesn’t really make business sense to do such a job when you can take a more profitable and lower hassle job elsewhere.

They also only want to support systems they have supplied, you can’t expect an installer to know everything about every system on the market.

If the Fogstar battery you have supplied starts playing up and needs to be swapped out (as my neighbours did), they are not going to be interested in supporting it. As mentioned above, there are also warranty and support issues relating to the inverter also.

Don’t get me wrong Fogstar is great for a certain kind of person with a certain knowledge level (aka be your own technical support) and willingness to get your hands dirty. But if you are posting on here with some pretty basic questions about what to look for in a system, that person isn’t you.

 

[Journey]

if you are posting on here with some pretty basic questions about what to look for in a system, that person isn’t you.

Nice writing people off when they just start exploring what is available, everyone starts somewhere, some will take a much larger interest in it once they see how broad the offerings are, others with take the easy way out and pay someone more and learn nothing for an easy life. Don't presume that everyone who starts off knowing nothing wants to continue that way.

 

[doodah]

@Ron-ski thank you.

I agree fully with Ron on this, electric underfloor heating is trash and it should be the absolute last resort.

We’ve got electric underfloor heating in our hallway, kitchen and dining room which the previous owners installed. I’ve turned it on once and watching the meter ‘spin’ I quickly came to the conclusion it was going to cost a fortune.

Cost wise you are looking at 4x the price of gas or heat pump to heat a room.

If you are going to spend a bunch of money putting in electric heating, do a heat pump and/or proper wet UFH.

Don’t forget, you are only going to be using electric UFH in the winter, solar generation will not be covering it and there is a cost gap between export and peak rate import.



It might, it might not matter too much. As as many of your panels are sub optimal in terms of orientation and being in the U.K. your sustainable peak generation will only be 70-80% of the theoretical maximum. Most hybrid inverters can be ‘over panelled’ by 150% some will take 200% of their capacity in solar panels.

With a hybrid inverter, you can charge the battery and export to the grid at the same time so even if you are hitting up against a DNO limit, you’ll still be able to generate the electricity.

Putting panels on the NW roof will be cheaper to install than the detached garage. You might need a second inverter but the garage can be covered by a small string inverter or micro inverters. That will probably be cheaper to install than running DC cable back to the house anyway.

You don’t need 3 phase that’s for sure.

Thanks. I'll reach out and see what it costs to add NW roof panels. Would it be worth getting panels more suited for shading? Panels in Skylar quote are below (nine for the roof and extension, four for the shed).

9 × Aiko 485w Black Frame 3rd Generation With White Lines
4 × AIKO AIKO-G645-MCH72Dw(Q4-2023)

As for running cables from the shed to the house, we'd be doing this anyway as we want to house the battery and inverter there. So would having the cables for possible shed panels make much difference?

Noted about electric UFH, that's all I need to hear .

 

[b0rn2sk8]

As for running cables from the shed to the house, we'd be doing this anyway as we want to house the battery and inverter there. So would having the cables for possible shed panels make much difference?

No, not in that scenario.

I assumed the main hit would be installed near the house. This explains why the cost is comparativly high for a relivily small install, they'd have to run 2-3 strings down to the shed in DC and then run AC and data back to the house.

If you installed the battery and gateway on/in the house, you'd only have to run a single set pair of DC back to the house or if you put the shed on its own inverter and run that into the existing power supply if there is one. You can probably see how this would be significantly cheaper than housing it in the shed.

In any case, if you do the NW panels on top of the other 3, you'll need a 2nd inverter because the larger single phase SigEnergy inverters only have 3 MPPT's, the smaller ones only have 2. You'll have 4 arrays and while they are all in the same orientation, I doubt they are the same pitch. You should only really put pannels on the same MPPT if they are all on the same pitch and orientation.

 

[b0rn2sk8]

Nice writing people off when they just start exploring what is available, everyone starts somewhere, some will take a much larger interest in it once they see how broad the offerings are, others with take the easy way out and pay someone more and learn nothing for an easy life. Don't presume that everyone who starts off knowing nothing wants to continue that way.

I'm sorry but the OP clearly isn't in a DIY place and you jumped straight to 'install a DIY battery' with zero context as to thats what it is. It just isn't helpful.

 

[Journey]

I'm sorry but the OP clearly isn't in a DIY place and you jumped straight to 'install a DIY battery' with zero context as to thats what it is. It just isn't helpful.

No I said use an installer... but whatever.

EDIT: Also for your lack of information Deegee have been around ages and install Fogstar fully MCS etc.

Fogstar Batteries with Solar Panels | UK Solar Battery Installers

Thanks to their rugged durability, scalable design, and affordability, Fogstar batteries are the perfect match for any solar panel system.

www.deegesolar.co.uk

So year so hard finding installers to get good value... and support...

 

[doodah]

No, not in that scenario.

I assumed the main hit would be installed near the house. This explains why the cost is comparativly high for a relivily small install, they'd have to run 2-3 strings down to the shed in DC and then run AC and data back to the house.

If you installed the battery and gateway on/in the house, you'd only have to run a single set pair of DC back to the house or if you put the shed on its own inverter and run that into the existing power supply if there is one. You can probably see how this would be significantly cheaper than housing it in the shed.

In any case, if you do the NW panels on top of the other 3, you'll need a 2nd inverter because the larger single phase SigEnergy inverters only have 3 MPPT's, the smaller ones only have 2. You'll have 4 arrays and while they are all in the same orientation, I doubt they are the same pitch. You should only really put pannels on the same MPPT if they are all on the same pitch and orientation.

Ah okay. We're really not fans of having the install inside the house - the only place it could even go is the utility room which conveniently is next to the CU under the stairs (through a wall). One installer said we can run the cabling under the plant beds; left would require lifting the stone slabs and whilst right is more intensive - we should be able to tuck it under the soffit/not need to lift the slab. The wiring would then go back into the house round the side, into the utility room then CU under the stairs.

Alternatively if we had it on the exterior of the house, one of the green Xs seem the best choices but one interferes with our garden furniture and the other is next to the BBQ which doesn't seem ideal. I'll go back to Skylar and Little Green for some adjustments around placement of batteries and inverter + NW panels.

 

[b0rn2sk8]

It’s fine externally, so it’s worth asking how much cheaper it would be if you are happy with that placement. I wouldn’t put it inside a typical U.K. house, if you had a big plant room sure but your typical house doesn’t have the space.

Any cables between the two buildings should be trenched at least 60cm deep unless there is something solid to surface clip to (a fence isn’t considered to be solid in the regs, it’s a temporary structure). In theory you are paying someone hundreds of £ per day to dig a hole (unless you do it yourself).

 

[doodah]

It’s fine externally, so it’s worth asking how much cheaper it would be if you are happy with that placement. I wouldn’t put it inside a typical U.K. house, if you had a big plant room sure but your typical house doesn’t have the space.

Any cables between the two buildings should be trenched at least 60cm deep unless there is something solid to surface clip to (a fence isn’t considered to be solid in the regs, it’s a temporary structure). In theory you are paying someone hundreds of £ per day to dig a hole (unless you do it yourself).

Yeah both companies said they're fine outside but just not keen unless it comes to it. I pretty much dug both plant beds with some help from my mother in law, what's another 60cm trench . I'm going to double check because I think there might be a visible concrete base running along the base of the fence. Would that count as solid?

Edit - it's a 2 or 3 stack of bricks.

 

[b0rn2sk8]

Yes in theory (assuming it’s a motored in as a wall and not just stacked).

I’d still want the runs to be done in SWA though given how vulnerable they’d be to a stray spade.

 

[Ron-ski]

The shortest route would be the best route.

 

[doodah]

Yes in theory (assuming it’s a motored in as a wall and not just stacked).

I’d still want the runs to be done in SWA though given how vulnerable they’d be to a stray spade.

SWA?

The shortest route would be the best route.

Not against that route, need to see how much it would cost to lift a stone slab and put back.

As for the shed, it needs a bit of love (hangover from previous owners) as you can see in the pics below. One installer seemed to think it could go behind and to the left of the freezer. My worry ground mounting it is the weight. It looks like stone/concrete floor below and raised wooden flooring above this, but these panels feel flaky. Me standing on one broke it last year and we're potentially installing something over 150kg on them. So wondering if we should redo the floor (either new wooden floor on top of the stone or take out the aging wooden flooring all together).





The fenced in section where the freezer sits is exposed to the stone/concrete. The walls need some attention to, think the previous owners tried to fill that gap with some foam.

 

[b0rn2sk8]

SWA?

Steel wire armoured cable - it’s more expensive but you’ll struggle to put a spade through it on the first go.

Standard outdoor cable a kid could easily put a blunt spade through in a single hit.

 

[doodah]

Steel wire armoured cable - it’s more expensive but you’ll struggle to put a spade through it on the first go.

Standard outdoor cable a kid could easily put a blunt spade through in a single hit.

Oh right, completely agree. We have one to the shed slightly tucked in on the shorter plant bed. I found an old one making the plant bed, confirmed it wasn't live and had at it. Tough things!

 

[Ron-ski]

Shortest distance is best due to voltage drop, the longer a cable the more the voltage drops, potentially meaning larger diameter cables are required. With PV you need to keep the voltage drop low on the DC cables and the AC cables.

Depending on what's under the paving slabs it could be easy, or a PIA if concrete. I'd take an exploratory look, just in case it's easy.