Going fully solar/electric

I’m at the dangerous phase of knowing a little bit about solar, without being expert enough to know if my idea would work.

Gas/boilers seem to be on the way out. I’ve decided I want to utilise my 30m, south facing roofline in SE England to generate enough solar for my needs.

If I were to fit a large solar PV + battery system, utilise an off peak electricity tariff, is it crazy to think I can convert my domestic heating to electric too? A mix of lower winter solar and off peak battery charging should suffice most of the time?

Obviously proper calculations will be needed eventually, but is this even viable?

You won’t be completely off grid in December unless you insulate to Passivhaus standards. You get about a quarter of the rated Summer output just when you need the most heat.

Have a look at your gas bill and work out how many kWhs of gas you use in December now. I think you might be surprised at how much energy you are using and that solar is only viable if you reduce that. That said if you heat with a heat pump, at current gas and electricity prices you may decide electric is viable even without solar. I’m against battery storage, the electricity suppliers can do the buffering for you and probably better than you.

bookmarking

I’d also ask what are your insulation levels like?

Insulation upgrade in the loft is my first job. It’s a 1930s build with cavity walls.

I know I will use some grid energy, but with the ability to charge the battery overnight at cheap rates, then empty it for morning heating, I reckon it should work.

Current energy price craziness makes it impossible to work out accurate pricings.

Obviously proper calculations will be needed eventually, but is this even viable?

It is possible.

Will it be cost effective? Unlikely.

Will you have to compromise in all sorts of ways? Yes.

Is it easy? No.

Is it worth doing? Likely.

Lets not forget that micro-generation (unless it is hydro) is pretty inefficient for all sorts of reasons. Large scale generation is much more efficient in other ways.

The best thing we can do is huge reductions, rather than just generate more.

I’m struggling to see any efficient technology for the masses to replace gas.

Whilst financial gain is part of it, I also want my domestic emissions reduced.

This is what I get from a 100% unshaded south facing 3Kwp system in N Wales – see what size system you can fit on your roof and scale up accordingly.

I too would be sceptical about battery storage – just to expensive – but then I might be wrong.
You could look at solar thermal as well but it’s a one-trick pony.

A stove would make a massive difference. We survived for the last two winters with just a stove in our kitchen/breakfast room/snug/dining rooms (approx 15m x 10m).

I’m struggling to see any efficient technology for the masses to replace gas.

If it’s efficiency youre after then the answer is electricity – but the question is cost.
Get the price right and it’s the answer….. but until then….

I have a wood burner too, but I’m not sure that will be acceptable in the future.

My other hope is the “much talked of” conversion of the natural gas network to hydrogen.

I would get someone knowledgeable to help look at things like construction, insulation and air-tightness first to give you an assessment of what you could achieve given the fabric of the building and potential EPC. You’d then be able to assess the options available for heating, solar, PV etc.

I wouldn’t go so big so quick. I’d maybe start with a 5kw system, with an inverter big enough to cope with any future improvements. There’s no grants, little in the way of FIT, so all that mass of solar panels will head back to the grid without you seeing a penny. A solar immersion control like the iBoost will give you a decent amount of hot water for a small outlay. Batteries IMO are a red herring. Wait 5 years and they’ll be half the price.

Something that an architect friend said to me always sticks in my mind. ‘If you add together all the tiny gaps and cracks in your house where warm air can escape, you’ll find it can easily be the same area as an open window or even a door’

I would get someone knowledgeable to help look at things like construction, insulation and air-tightness first to give you an assessment of what you could achieve given the fabric of the building and potential EPC. You’d then be able to assess the options available for heating, solar, PV etc.

Good luck with that. There is a gap in the market in that this role doesn’t really seem to to exist.

A solar immersion control like the iBoost will give you a decent amount of hot water for a small outlay.

I have a combi – so I plumbed something similar into a 2kw oil radiator in the most used room in the house keep it warm during the day when we are not using the generated leccy for other things. Considerably less heat required when we get home.

Not a great use but the leccys there anyway and the house does need much less oil fueled energy to get to temp when we get home.

This video indicates around £4K +vat for a 8kw battery install and estimates ~4 yrs payback, might be worth a look.

Yep our holiday place has an Immersun that feeds the hot water tank first and when that’s up to temperature it feeds a dedicated socket in the hallway that has a simple panel heater plugged in so any spare electricity turns into heat.

(An oil rad isn’t quite as good as they take more power before they start emitting heat – cheap and cheerful panel heater throws out heat in seconds which is good for an intermittent supply)

Yes, Ive watched EVM’s videos as part of my google research.

I’m struggling to see any efficient technology for the masses to replace gas.

Whilst financial gain is part of it, I also want my domestic emissions reduced.

You and me both. I’ve just installed a 5kW solar array and will have battery backup when Elon can make a Powerwall for me. I have an oldish gas boiler and I’m starting to wonder if I should replace it before the government bans the sale of them but like you I’m struggling to see how a heat pump is financially and practically realistic even in a well insulated, double glazed house constructed to normal building standards. Besides all that the sheer size and appearance of the things is off-putting and although its claimed modern ones are quieter I still worry about noise and vibration in the house and getting noise complaints from the neighbours.

I think stopping the use of gas for domestic heating is going to be a much harder nut to crack than moving from ICE vehicles to EVs. For a start electricity is cheaper than petrol but its five times the price of gas. Now we could make electricity cheaper by moving the renewable levy onto gas but someone struggling financially to heat their house with gas is not going to be able to afford to heat their home on electricity even if its a bit cheaper let alone afford a new heat pump.

This video indicates around £4K +vat for a 8kw battery install and estimates ~4 yrs payback, might be worth a look.

I was going to link to this one as well. However his man maths only works out if overnight cheap tarriff stays at 5p per kWh which I bet it won’t.

He does make the good point that unlike a solar array its a lot easier to take your battery with you when/if you move.

Whenever I look into to cheap night tarifs they end up more expensive given the higher standing charge and punitive day-time tarif that goes with them.

The best thing we can do is huge reductions, rather than just generate more.

Having to generate all your own electricity is a good way of reducing though.

An oil rad isn’t quite as good as they take more power before they start emitting heat – cheap and cheerful panel heater throws out heat in seconds which is good for an intermittent supply)

Arguably a panel heater flattens out the hysterisis which is why I went for an oil heater. I am not needing instant heat I want to heat a volume to release the heat over a period

But net energy out is near as damnit net energy in in either case.

With batteries and storage, I can see changes shortly.

Might we have house by house or Street by street alternative storage? I’m talking thermal, chemical or mechanical…

Think mini versions of Cruachan, with a tower on each street…(etc)

OK.
My theory, though, is that with a potentially intermittent power supply of rather take what heat I can when it’s there.
🤔

A panel heater will also just keep producing heat whist I think an oil rad will switch off when the oil reaches a certain temperature.
This is good when using mains power but I want to use every last watt of solar power.

Oil rad over 99% efficient in tests.

If I’m producing 2kw long enough in winter to reach the thermal cut off of I’ll consider that but it’s doubtful that’ll ever happen .

A dehumidifier does better than 100% as you get the latent heat from condensing the water. I worked it out for mine but can’t remember the exact numbers, of the order of 130% IIRC.

But it also needs a minimum /sustained input to set it going & frequent emptying

Convinance is king.

Just a thought but can a PV array not be used to run lighting and small power systems at 12V without the need to convert to 230v via an inverter and incur the losses that must arise from this?
Lighting and certain appliances can easily run off 12V DC so I’ve often wondered why we don’t replace wiring systems for DC installations to utilise PV rather than rectifying it to 230v?
Most nights if it’s just me and the wife in we only have a lamp or two on and probably just watch a laptop or tablet for TV or movies so aside from cooking and the washing machine running we are not generally pulling much electrical load from the supply. Pretty sure a half decent leisure battery could be charged to handle this for about 4 hours a night? Also wonder if PV wouldn’t be enough to run my pc and monitor during the day, and a single 10W led lamp as that’s pretty much all I run when WFH. 400w running load??

frequent emptying

They have a pipe outlet you can connect to the bathroom plumbing.

Edit to elaborate. Using either a heat recovery ventilation system or dehumidifier to keep humity down not only keps your house dry but also makes it feel warmer because damp air feels colder. Other things that make you feel cold are cold surfaces. Standing in front of a cold surface will feel colder than a warm surface for a given air temperature. Insulated walls and triple glazed windows don’t feel cold to stand in front of so you feel warmer with a lower air temperature. Put the two factors together and you feel comfortable when the thermometer tells you it’s a couple of degrees colder.

They have a pipe outlet you can connect to the bathroom plumbing.

Some do your also Assuming everyone haz a pipe near the area you want heating/sorry I mean drying….

And solar PV isn’t 12v it’s 500v DC peak

Mine is 700v DC peak IIRC, it depends how many panels you connect in series.

Even if you don’t plumb in the dehumidifier it’s not much of a chore to empty it once a day.

Lots of interesting chat in this thread. I too am looking at options for leccy only. A good friend is in the middle of getting PV+battery with enough storage to run the heat pump he is also trying to get (stock in high demand). We are having the house extended in 18 months and the boiler would have to be moved. I’d rather replace it with something more future proof as it would mean we don’t have to worry about accommodating it in the design either.

Ah…right, to be honest I was kind of going by the single panel my mate has on the roof of his boat so wrongly assumed a home or commercial PV array was 12V stepped up to mains voltage. Ok so any form of charging/storage will require a level of marshalling equipment then which may ultimately mean that running low voltage systems is not beneficial? Still…high load appliances aside a PV array might be ok to power (via marshalling equipment and some storage) general small power and lighting to a small dwelling for a few hours each night plus direct usage of say a pc, monitor and lamp through the day??

Even if you don’t plumb in the dehumidifier it’s not much of a chore to empty it once a day.

It’s enough of a chore if you have a full time jobs and a child they are also noisy when working while the heater sits there doing it’s thing silently day in day out with zero issues it’s also portable.

(Having lived in a rental flat that needed two running all the time I won’t be going back to that regardless of efficiencies)

A PIV on the other hand.

Ive just had solar installed with a battery. 10 panels on the roof 4kwh, 3.3 kwh battery. So far it seems great when the sun shines. Not looking in going totally electric yet, but hoping to in the future. The system came with the iboost but i haven’t got an immersion so couldnt be fitted.
I also have a catalogue from a company called Fischer Future Heat, they have some interesting stuff like electric boilers and radiators etc. Not sure on prices though. Phone number: 01162425533 or 08001032705, email: info@fischerfuture.co.uk

Anything that goes against your idea that oil-fired central heating is the perfect solution for you gets you coming out with some remarkably tenuous justifications, Trail_rat.

Six seconds to empty the dehumidifier in the bathroom if not plumbed in, I’ve just timed it. It also takes 6 seconds to plug it in, turn it on and select 60%.

How long do you spend on this forum a week?

some remarkably tenuous justifications

And the noise ?

And for the record. As you state…. The perfect solution for ME. I’ll decide what the perfect solution for me is. There are some on here who’s advice I’ll heed.

As I said I’ve lived with your solution in the past. Its an informed decision. It was used to patch up a house with inadequate ventilation.

Well the perfect solution for you isn’t the perfect solution for some others or the objective of reducing carbon emmission and the Op asked sensible questions so I provide sensible suggestions. Suggestions that are science based, make for comforatbale living and may help people to reduce their carbon footprint.

I know you’re into oil fired central heating and diesel cars, Trail_rat, you’ve contributed to enough threads extolling their virtues. But some peple are trying to get away for that and starting future looking threads such as this one. I know that if one of your posts follows one of mine it’ll be to slag off my post. You’ve been doing it for years.

I hope that so much negativitiy about a device as simple, effective and usefula as a dehumidifier provides entertainment for other members if nothing else. Anyhow my explanations are there for all to see and they stand up to examination.

I switch mine on in the ventilated bathroom after a shower because it clears the damp air and provides some very efficient heating at the same time. Noise? Not an issue ofr me.

Actually forget it.

Your so predictable.

*Goes back to reading oil fired heating monthly*