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Solar Panels UK - is it worth it?
- Thread starter jdwuk
- Start date
david1701
Member
Im on Octopus Go Faster until the end of this September, 13.5p peak and 5.5p off peak, just us two adults, gas cooker n boiler, I've been thinking we can live off the powerwalls, being charged up by solar atm, and still if they charge at off peak 5.5p, and I really don't like Tesla taking control of them, I'm diverting any excess generation straight into the Model S for free motoring when I can, think ill wait n see what happens to the price cap in the autumn and what Octopus offer when my Go Faster runs out in September.
Take the average property, 8kwh electricity and 33kwh gas, and make it all electric, and no doubt more storage could make sense.Let's just run with your example of 70p per day (35p peak rate)
That's £255 per year. £2,550 over 10 years.
and... you've got the 13.5kWh capacity savings throughout each year on top of that. Be it stored solar, or cheap rate tariff.
13.5kWh per day at 35p = £ 4.72
13.5kWh per day at 7.5p = £ 1.01 stored cheap rate
Saving £1,354 per year. £13,540 over 10 years.
Makes using Heat Pumps very cheap.
... and we're not even talking ROI on free Solar mixed in
I paid £6500 for my second Powerwall, and we use it every single day. So it'll pay for itself.
My point was really about the average user, and not an extreme case. But acknowledge it works for you.
RedMod3
Member
Very unlikely as I do not want anyone other than myself controlling my power; there would have to be a major and not a minor cost saving.
RedMod3
Member
I wonder, could the Givenergy supply be included in the solar CT clamp? I guess the worry is, how do you stop the PWs from charging the Givenergy batteries?
I'll ask my installer.
WannabeOwner
Well-Known Member
Sounds awesome
Do they have an API? Might not be your bag ... but with an API something could be rigged up to adjust the output from GivEnergy, based on household usage. e.g. could "mirror" it at 100%, until GivEnergy was flat, and then PowerWall would take over. Or if 100% would result in some over-run / export of a few watts, then "mirror" at 90% ... or 80% ... whatever works without causing export.
Just a thought.
What is really need is a 2 megawatt battery that I can charge from solar over summer, store and use in winter.
When that’s affordable I can be self sufficient… I can dream!
In a way, I guess that‘s what TEP is!
When that’s affordable I can be self sufficient… I can dream!
In a way, I guess that‘s what TEP is!
The problem with trying to compare the different Octopus packages is that we are all on different rates depending on how lucky we were on renewal? I've been on TEP since October 2019 because the initial rate was fantastic and no standing charge. I had several months where TEP were paying me. When the new rate came in with a standing charge and an increase to 11.1 in/out., the major change to my bill was the standing charge. At the moment I would be better off with a 5.5/14.5 GO fix, but that isn't available. On the current GO fix, I would need a second PW to switch and still win. However we have yet to see what the rates will be when I renew in October. Who knows? but then it isn't the biggest problem with my home energy, which is gas currently up from 2.9p to 7.3p variable and definitely going to at least 11/12p in October? That is 400% up in 12 months!
WannabeOwner
Well-Known Member
I did some sums for how big a block of concrete I would need, and how high I would need to winch it in Summer ... to provide all my electricity generation in Winter. I thought I could just build it into the centre of the house ...
... the sums weren't favourable
Seasonal thermal energy storage might do for heat, but I dunno about seasonal electricity storage.
it doesn’t work that that though except with off-peak only. With Solar even during winter you’ll be generating some solar. So the PW will discharge in the morning, but will trickle in solar during the day, reducing the speed it discharges, then the PW will take over again in the evening. in your example you’d need 1kwh generated by solar during the day which will go into the battery (or consumed directly, doesn’t matter) which means the PW now only needs to deliver you the other 13kwh you need for the house.
for an average 14-15kwh consumption, a 10kwh battery will do a lot of good combined with solar. anything more is covering edge cases or off-peak only
I did some sums for how big a block of concrete I would need, and how high I would need to winch it in Summer ... to provide all my electricity generation in Winter. I thought I could just build it into the centre of the house ...
... the sums weren't favourable
Seasonal thermal energy storage might do for heat, but I dunno about seasonal electricity storage.
just curious - what did you end up with? maybe a Garden H2 generator?
When I did my calcs a couple on months ago it was "slightly ahead" for TEP.
If you count slightly ahead as payback being 1 year earlier over a 9/10 year year period.
Like quite a few others I am no that keen on handing over control, I am glad I have 6 months to work out/decide if the cost becomes compelling one way or the other.
Just had tanjent round - first company to actually do a site visit. Will get a quote for a 9.5 givenergy battery and optional approx 4kw north facing solar which would help even being less effective on a 24 degree roof. I might want more battery but let’s see what this comes back as first
WannabeOwner
Well-Known Member
Nothing
We live in a Passive House, so that takes care of Thermal. But electricity usage is high (servers and other stuff that uses 1.5 - 2kW background
)Yeah, that sounds like a fun project
PITA
Model 3 Performance
Yes agreed.
We used to be a normal house usage, until we went 100% electric.
Since then our electricity use has quadrupled.
Hi,
Just after some views on how long it has taken other people to get on the Tesla Energy plan, I switched over to Octopus on the 21st April, and had all of my documents/info ready; DNO, MCS certs, GW S/N etc etc. and requested to switch from the Flexible Octopus tariff you land on over the TEP immediately. So after much chasing and getting nowhere with Octopus I wanted to see if this is the same as everyone else's experience? Currently 4 weeks to do something they said would take 1-2 days, 5 max when I first enquired, its so frustrating as I am in the main solar generation season and its currently flowing onto the grid for nothing.
Thanks, Alastair
Just after some views on how long it has taken other people to get on the Tesla Energy plan, I switched over to Octopus on the 21st April, and had all of my documents/info ready; DNO, MCS certs, GW S/N etc etc. and requested to switch from the Flexible Octopus tariff you land on over the TEP immediately. So after much chasing and getting nowhere with Octopus I wanted to see if this is the same as everyone else's experience? Currently 4 weeks to do something they said would take 1-2 days, 5 max when I first enquired, its so frustrating as I am in the main solar generation season and its currently flowing onto the grid for nothing.
Thanks, Alastair
I'm in the South, so it's about 45p for electricity. I read that because "everybody" has electricity and only some people have gas, the costs born by Bulb (and the others) going into special admin was spread across everybody's standing charge. Martin Lewis had asked it be spread across the cost of energy instead - and another reason why he got sweary with the regulator! The cost just of Bulb going bad is well over £1bn every 6 months. They basically did not hedge their energy prices. So eg. 1.6 million people buying energy off them on their fixed deals at say 16p, but it costing them 25p/kWh!
Bulb never offered fixed prices. Only variable. It’s the gvt price cap that killed them as they indeed did not hedge forward, and then couldn’t pass on the cost to the end-user. As a customer, I cannot complain, had a great deal for years
I've spent a few days going through every post in this thread. I've learnt more here than just about anywhere on the web (so thanks to all) and.....
I still haven't a clue as to what I need!
I'm moving back up north in a couple of months and looked at 4 houses, three of which have perfect, empty south-facing roofs but no, the missus decided on the fourth one which is SSW-facing and has an apex, 3 windows and a solar water heating panel on it:-
My Roof
The picture shown was from a full PV/battery quote generated by a UK-wide installer (all within 45 minutes of a call taking minimum details so kudos to them).
The 8 panels are 390W (Trina Vertex S) or 395W (Q Cells 395W Mono Q Peak Duo ML G9) and generate ~3.16 kWp with the estimated output being 2,686 kWh.
I asked about different panels to maximize output for the limited roof space (I've seen ads for 500W) but was told there isn't room for more/they aren't in stock anywhere/they cost much more.
Newbie questions:-
Should I continue looking for bigger wattage panels being stocked since I'm only going to get one shot at this system and don't mind waiting a bit?
Does anyone manufacture half-size panels for filling in the gaps? (can you mix panel models on a single string anyway?)
Should I get rid of the existing solar water panel to make a bit more space for PV panels or leave it alone? (It is attached to a Viessman boiler system apparently)
When comparing solar panels, what is the relevancy of the efficiency? Hasn’t it already been taken into account to calculate the output?
I still haven't a clue as to what I need!
I'm moving back up north in a couple of months and looked at 4 houses, three of which have perfect, empty south-facing roofs but no, the missus decided on the fourth one which is SSW-facing and has an apex, 3 windows and a solar water heating panel on it:-
My Roof
The picture shown was from a full PV/battery quote generated by a UK-wide installer (all within 45 minutes of a call taking minimum details so kudos to them).
The 8 panels are 390W (Trina Vertex S) or 395W (Q Cells 395W Mono Q Peak Duo ML G9) and generate ~3.16 kWp with the estimated output being 2,686 kWh.
I asked about different panels to maximize output for the limited roof space (I've seen ads for 500W) but was told there isn't room for more/they aren't in stock anywhere/they cost much more.
Newbie questions:-
Should I continue looking for bigger wattage panels being stocked since I'm only going to get one shot at this system and don't mind waiting a bit?
Does anyone manufacture half-size panels for filling in the gaps? (can you mix panel models on a single string anyway?)
Should I get rid of the existing solar water panel to make a bit more space for PV panels or leave it alone? (It is attached to a Viessman boiler system apparently)
When comparing solar panels, what is the relevancy of the efficiency? Hasn’t it already been taken into account to calculate the output?
Quite the challenge there! Is there any way to get a rating for the water panel? Bring it back to fundamentals - how much benefit can it give you, and does removing it (£££ associated I assume?) allow more watts of PV to be installed? Would that pattern of install be more acceptable in terms of visuals?
That said, my parents have a similar problem, lovely empty roof, to the north. South is full of veluxes, dormers and all sorts
. But being way up north they do have a chunk of space and I found Solivus Arc Solar energy solution which they now have a noted interest in.Overall, depending on your lifestyle and aims, 8 panels is no bad either? You won't go grid free, but it will take a chunk out of the bill?
I don't think anyone does small panels - the edges make up a significant part of the losses from ideal and the way to minimise that is by increasing panel size as much as possible. The 500w panels you have seen are likely even bigger - the thing to look to is the efficiency of the panel, not the wattage. Lab level stuff is topping out at ~30%, good commercial is about 22/23% to give a 420w standard panel I think (ie Tesla ones). I'm installing 22x375w panels at just over 20% as the size of the install meant I didn't have to wring every last watt from it or fight over the limited supply of the good stuff. Efficiency x size does indeed give you the output.
With PV it is super simple - more is just more. Unless you hit exponential cost increases from supply probs or cutting edge stuff, it pretty linearly translates to savings. Equally, even a guy who invented and is ramping up the next gen level of commercial efficiency (Leaders in perovskite solar technology | Oxford PV - initial production due this year at 27% efficiency, due to ramp to 30%) has said the best panels are the ones installed on your roof, otherwise you will always be waiting.
As a heat pump and EV user I can in all honesty see us upgrading some our panels in 15 years time once they are well paid off. Family over the road from us have a few FIT panels from a good few years ago, and they generate diddly squat compared to a more modern solution - can only imagine it will be the same in the future for us.
