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Solar Panels UK - is it worth it?
- Thread starter jdwuk
- Start date
RedMod3
Member
They can and will charge at 5kW in storm mode, but usually charge at 3.6kW. I've had mine restricted to 3.6kW as I don't want to blow the 100A fuse.
Has anyone tried restricting the off-peak period to 2/3 hours in the Tesla App to see if the PWs charge at 5kW and not 3.6kW?
Similar sized house and family, most days it's 9KWH unless we are doing laundry where it can be 15. No electric shower though.
Recently we've been using about 65KWH of gas, so even with a Heatpump at 300% efficiency that would be still only 30KWH a day total.
WannabeOwner
Well-Known Member
Mine charge in 3 hours ... "pretty much". If car is charging (or other heavy-load) at same time they (i.e. two of them) drop from 10kW to 6.5kW
Mine automatically drop back if there are other heavy loads, so not sure it is necessary to restrict max power?
phil4
Member
Your bigger problem is most people aren't allowed to export from their Powerwall, so you'll not be able to make use of the better export rates on Flux either. So no, if that's the sort of thing you were thinking of, better to go with a Hybrid inverter and DC battery solution, then the DNO can't see it and ban export.
Pete UK
Member
Yeah we have a large kitchen with high ceilings. Victorian property. Crap (if any) insulation. 18-24” solid brick walls. Can’t insulate the walls effectively, as it means they freeze on the outside in winter and damage the bricks.
The kitchens only heat source is the electric underfloor heating mats. It’s a 7.4kW underfloor system. So probably most of our house power is going on that.
Seemed a good idea at the time. Not so much now
I’m gonna try and get 2 rads installed to at least get its usage down and possibly retire it. Which might change the numbers a bit.
No heat pump here. Gas CH.
ElectricPolice
Member
0
Firstly, I'm no expert in this, some of the content on here makes my head hurt, and I've got enough other things I need to allocate brain space to!
I have 5x Fox HV2600 batteries and they are set at 25A charge current which is the recommended rate (lowest I guess?) set by the installer. According to whichever spec sheet I read the accepted settings can go upto 50A. However, in my circumstance I get a full charge from 10% upto 100% in 3 hours so I set it to start at 02:30 that way it plateaus nicely come end of off-peak window.
As regards car charging and other usage it has no real impact as far as I can tell?
Here is last nights inverter data...
From 11:30 I'm charging the car on 7kW and have dishwashers and portable radiators on. At 02:30 the batteries start charging, as you can see, and then tails off when full and trickling. Car stopped charging at 03:58 according to the Tesla app. Electric heaters remain on until 05:30 to warm specific rooms and reduce need for gas CH to work so hard.
Here is my corresponding SOC for the battery... but for the full day so far. I have run 1 wash and 2 tumble drier runs today and the sun is making an appearance. At this rate I'll be off grid all evening until cheap rate again.
In relation to the concerns about IO not always being there, life's to short to worry about what I can't control. I'll swap to whatever is available at the time like I always do. Only so much crystal-balling I can do
.
Hope this all makes sense?
Thanks for your comments.
Firstly, I'm no expert in this, some of the content on here makes my head hurt, and I've got enough other things I need to allocate brain space to!
I have 5x Fox HV2600 batteries and they are set at 25A charge current which is the recommended rate (lowest I guess?) set by the installer. According to whichever spec sheet I read the accepted settings can go upto 50A. However, in my circumstance I get a full charge from 10% upto 100% in 3 hours so I set it to start at 02:30 that way it plateaus nicely come end of off-peak window.
As regards car charging and other usage it has no real impact as far as I can tell?
Here is last nights inverter data...
From 11:30 I'm charging the car on 7kW and have dishwashers and portable radiators on. At 02:30 the batteries start charging, as you can see, and then tails off when full and trickling. Car stopped charging at 03:58 according to the Tesla app. Electric heaters remain on until 05:30 to warm specific rooms and reduce need for gas CH to work so hard.
Here is my corresponding SOC for the battery... but for the full day so far. I have run 1 wash and 2 tumble drier runs today and the sun is making an appearance. At this rate I'll be off grid all evening until cheap rate again.
In relation to the concerns about IO not always being there, life's to short to worry about what I can't control. I'll swap to whatever is available at the time like I always do. Only so much crystal-balling I can do
.Hope this all makes sense?
Air to Air Heat Pump (AirCon) might be worth considering, cooling in summer will be effectively free from your solar.Yeah we have a large kitchen with high ceilings. Victorian property. Crap (if any) insulation. 18-24” solid brick walls. Can’t insulate the walls effectively, as it means they freeze on the outside in winter and damage the bricks.
The kitchens only heat source is the electric underfloor heating mats. It’s a 7.4kW underfloor system. So probably most of our house power is going on that.
Seemed a good idea at the time. Not so much now
I’m gonna try and get 2 rads installed to at least get its usage down and possibly retire it. Which might change the numbers a bit.
No heat pump here. Gas CH.
ElectricPolice
Member
That's exactly my plan!
Replacing the fairly recently installed combi boiler is a no-no. Also we have microbore which would also need replacing so don't want to go down the air-water source (c.£15k??)
I'm considering an AC unit for summer cooling and winter heat in 3 rooms, living room, master bedroom and conservatory, as this is unbearable in the height of summer, but such a lovely bright space. I have also researched certain units (Daikin?) which also filter the air and can dehumidify/humidify which would be beneficial as we have a portable dehumidifier in the conservatory already.
Anyhow, prices come in around £5-7k depending on how fancy a unit I spec? This is for the single outside unit powering 3 internal blowers. We'd leave the combi for the routine hot water and heating on the occasions when the house is full when the kids come home for holdiays.
Seems the most cost effective approach to get AC would be worth it on its own!!
Now a little bird mentioned that Elon has plans for HVAC so I'll be watching the livestream later... Will Tesla Announce a Home HVAC Unit on Investor Day?
RedMod3
Member
That is interesting. Do you have an import limit as my PWs charge at 3.6kW each. When the weather gets better, I'll set the cheap rate for 2 hours and see what happens.
Pete UK
Member
That’s great. Seems to be working nicely.0
Thanks for your comments.
Firstly, I'm no expert in this, some of the content on here makes my head hurt, and I've got enough other things I need to allocate brain space to!
I have 5x Fox HV2600 batteries and they are set at 25A charge current which is the recommended rate (lowest I guess?) set by the installer. According to whichever spec sheet I read the accepted settings can go upto 50A. However, in my circumstance I get a full charge from 10% upto 100% in 3 hours so I set it to start at 02:30 that way it plateaus nicely come end of off-peak window.
As regards car charging and other usage it has no real impact as far as I can tell?
Here is last nights inverter data...
View attachment 912577
From 11:30 I'm charging the car on 7kW and have dishwashers and portable radiators on. At 02:30 the batteries start charging, as you can see, and then tails off when full and trickling. Car stopped charging at 03:58 according to the Tesla app. Electric heaters remain on until 05:30 to warm specific rooms and reduce need for gas CH to work so hard.
Here is my corresponding SOC for the battery... but for the full day so far. I have run 1 wash and 2 tumble drier runs today and the sun is making an appearance. At this rate I'll be off grid all evening until cheap rate again.
View attachment 912580
In relation to the concerns about IO not always being there, life's to short to worry about what I can't control. I'll swap to whatever is available at the time like I always do. Only so much crystal-balling I can do
Hope this all makes sense?
I'd been quoted circa £1200 per room which seems astronomical to me for one hole and some pipe.
I'll happily take recommendations for F-Gas installers who want a cash in hand Saturday job!
My one Powerwall charges at 5kW quite happily while the car takes 7.2kW from the Zappi. Even when the ASHP kicks in during the night and takes maybe 3kW (14kW Eco Dan) everything keeps pulling those loads. Installer set the charge limit I think. No export from Powerwall set as well
You might want to take a read of this: Refurbishment Case Study 37 | Historic Environment Scotland | HES. OK, you can't get to pasivhouse levels, but a bunch reasonably easy to approach options in here, carried out by historic scotland on a very public building. Its the source I am using as I slowly persuade my parents to upgrade their victorian property.
WannabeOwner
Well-Known Member
DNO allowed everything here (best as I understand it). 48 PC panels, 2x powerwall, 2x 7kW chargers - single phase, 100A fuse
My advice to folk would be to very strongly consider this (Passive Haus or EnerPHit compliant retrofit). Its going to be a significantly higher sticker price than bunging some bits and bobs (including Air Con) on the house, but the comfort will be like night-and day, almost total absence of respiratory illnesses - like winter coughs and colds, let alone for anyone that is an asthma sufferer - and of course reduced heating bills for the lifetime of the building ...
Having had the benefit of living in a passive haus (just the new extension, but the old part of the house is well insulated, suitably air tight, and we also retro-fitted MVHR) for 6 years then if upgrading my house was not a realistic possibility I would, without hesitation, move to one that already achieved all of that.
We built our PassiveHaus extension for Eco reasons, but having moved in the Comfort and Health benefits are far more worthwhile and important (I now realise)
I'm with you on this (MVHR at ours going in on Monday), but it's an up hill struggle to persuade many others that the level of disruption for this is tolerable. Even enerphit would mean taking all the floors up etc I think to get to joist ends and so on? I may have the wrong idea tho.
I really liked the linked study as it allows a bit at a time approach - tight insulation up in the attic, then under the floor. For my parents place, they are already harled on the 3 non street facing walls, so a layer of breathable EWI on these, and some behind the plaster and lath insulation on the 4th side, applied a room at a time with re-decoration.
OTOH, if you are up for doing it proper and as a package, results would be better, but you have to face up to moving out for a while?
I do think the real answer for these things is taking on a street at a time if possible. Collection of similar aged properties will fall to similar approaches, then get a big team with the right specialists in to do them all at once.
Pete UK
Member
Very interesting. I’d get that done if I had a grant of £80k as well
Interesting about the walls though. Blown insulation behind the plasterboard. I don’t have plasterboard. Maybe I need to get my walls “dry lined” if that’s the correct method? Interesting about the permeable paint as well as the wall moisture content
How are you getting on with your PV and battery install mate? Got any tips/ results to share? How’s the battery charging/ discharging off peak going etc…?
The good, the bad and the ugly?
Seems like we may have similar type properties, so very interested in any tips?
Cheers
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WannabeOwner
Well-Known Member
Yes, all the leaky stuff has to be fixed. its a big job to do as a retro fit depending on the type of construction. If you have solid concrete floors it will be easy
Sometimes it is possible to do room-by-room (as part of normal "redecorating") but that assumes internal insulation, and (personally, and assuming that the external brickwork is not cherished) I think it is much better to wrap the outside. That keeps all the thermal mass within the building, which helps to smooth out solar gain and winter cold. We had -10C overnight temperatures for a week a few years back; I kept meaning to increase the UFH water temperature, or increase the number of hours "burn" ... never got around to it. Checked the Logs at the end of the week and the lowest overnight temperature was 0.5C lower than "normal MIN". So basically the temperature is so even, and the thermal mass (inside the external insulation) so efficient that its not worth bothering about. A summer heat wave takes a week before we start to notice it in the house.But not fixing the leaky stuff means that the home owner has to, forever, put up with all the problems that that causes ... heat leaking out of the building, draughts making you feel cold and turn the thermostat up, and inability to have Heat Recovery (on the mechanical Ventilation) 'coz Heat Recovery needs a balance of outgoing air to warm the incoming air. If only X% of the outgoing air goes through MVHR (and the rest leaks out of the building) then of course the heat recovery is adversely effected (massively even for a small amount of "other loss" as I understand it)
Nothing wrong with that, except that it does need a design which will ultimately properly join up the various bits of insulation. Once the building is really well insulated any cold bridge can have massive consequences (e.g. condensation forming and rotting building materials and so on).
Our build has a walk-around "gutter" with a parapet on the roof. That was (wrongly) formed with plywood to create a very gentle slope so the water found its way to the downpipe; Above the plywood was a waterproof layer of "poor man's lead", and below it the roof insulation - a massive thickness of Celotex. Completely waterproof ... but all the plywood rotted because of condensation caused by hot/cold changes inside the sandwich - because no heat was escaping from below. Replacing the plywood-ramp with a "wedge" of rigid insulation solved that
I imagine that an exterior "wrap" would be OK to live in ... but all these massive-rebuilding-projects are much better if you move out. We didn't ... we had the join between the old house and the new bit properly (and I mean "properly"
) sealed up until the day they opened it when the new bit was "pretty much done". But the dust and disruption was still enormous, and with benefit of hindsight moving out during the build would have been far better, Builders could have got on without having to leave us safe-passage to the house and would have avoided the clash of our comings-and-goings and their deliveries etc etcTerraced houses lend themselves to that. Both side party-walls don't need anything 'coz they are "warm" on the far side, so only front, back, top and bottom to do. Wrapping the outside of the whole street would be much better than one-by-one.
WannabeOwner
Well-Known Member
3 bed terrace house would likely cost more than that to insulate. That's the snag, as I see it, for upgrading the UK housing stock.
But ... if the workforce has, say, 5 less sick days a year what's that worth?
If we import, say, 75% less oil for heating - what's that worth? And what's THAT worth if we had to go to war in the gulf, just once, to protect the supply?
But if government said "Get this fixed, here's a grant" all the ex double glazing cowboys, currently selling PV, would be all over it like a rash and I very much doubt that tax payers would get the saving they were expecting.
The calculation needed is PHPP. You may well be able to do it yourself - its a spreadsheet into which you put every measurement (every wall, and every window / opening / etc. and the U-values for the various materials), and you wind up with a figure for the heat loss. You can then try "What if I put triple glazing in" and "THIS brand" vs "THAT brand", and the wall / roof / floor insulation options.. Passive Haus has a maximum heat loss value - its about 90% less than typical UK housing, and 75% less than a current building-regs Persimmon Taylor Wimpey Barratt new-build.
Whilst the comfort and health benefits would be the same significant improvement, the saving on heating fuel would take a century for PayBack for one of those new builds ... which is why it is such a pity that the Building Regs don't require Passive Haus standard (although I read that Scotland are going to enforce that shortly ... so maybe England will follow).
Once Passive Haus becomes widespread and well understood the clamour for those types of houses will mean that the price of old housing stock will plummet ... you know, like 2nd value of ICE once EVs are de rigour. I may have been dreaming for a moment there ...
government or council (don't remember I was little) updated all the houses in our street in the 70s. Outside toilets, coal shed, no indoor bathroom. knocked down and built a bathroom on the ends and updated things generally. We moved out while it was being done.
If the housing stock is shite, it can be fixed but needs the will. For government it'll be a balance of cost:benefit - if renewable generation can cope they'll likely say screw it and let us deal with our own messes unfortunately. hopefully they'll at least rebalance prices so electricity is cheap to use for heating vs gas as we migrate more and more away from gas.
If the housing stock is shite, it can be fixed but needs the will. For government it'll be a balance of cost:benefit - if renewable generation can cope they'll likely say screw it and let us deal with our own messes unfortunately. hopefully they'll at least rebalance prices so electricity is cheap to use for heating vs gas as we migrate more and more away from gas.
