Our leccy bill is somewhat steep (my fault - I run a dozen or so snake vivs with all the heating and lighting that goes with) so have been contemplating getting solar installed.
Has anyone used a decent firm who install for free then fleece you the feed-in tariff or are they all cowboys? Similarly any recommendations for decent installers or ones to avoid?
Read an article online that reckoned using economy nightvrate and a tesla power wall battery thingy was now a better option than panels
This was due to reduced feed in tarrifs and cheaper battery lpacks
Could be nonsense as it was by a company selling power packs and I didn't have time or inclination to sense check it throughly
When all the companies selling Solar seem to revolve around sending a salesman to your home insisting both you are your Wife/partner are there...that tells me all I need to know!
Solar won't do you much good in the winter but is starting to wake up again now.... In 4 weeks it should be putting out some decent numbers (circa 250Kwh for the month) and it just gets better from there.
Can't help with fitters as we've had it for years and the original ones have probably gone.
One of our installations was wired incorrectly though and they fed the output from the inverter straight back into the grid (on the wrong side of the meter) so we never got the benefit of our own generation!!
Forget the FIT payments now, but it is nice generating your own power
Some numbers. Tesla Powerwall approx £7500.
https://www.tesla.com/en_GB/powerwall
Capacity 14kwh.
Saving on off peak tariff approx 10 per kWh.
£1.40 per day.
Approx £500 saving per year.
Borrow 7500 from Tesco over 10 years its £9877 paid back.
So getting on for a 20 years break even. If it lasts that long and requires no ongoing maintenance.
I'm out.
Correction to above. Usable capacity is 13.5kwh. Roundtrip efficiency is 90%. So annual savings more like £450 a year with longer payback. If ever.
Also ignores any higher daytime rate that cheap night tariffs have.
So far everyone has ignored basic geography, so far so STW.
The benefit will be entirely dependant on your houses location, elevation and facing direction as well as the panels used. The peak benefit is along the south coast of England which then tapers off sharply up to the Midlands IIRC after which its all much a muchness until you clear the Scottish central belt. It's been some time since I looked at the maps so that may not be quite true but it's the general jist of it.
You are limited to a 3.7kw installation on a single phase domestic supply.
You need a 3 phase supply to install more, unless you don't connect them to the grid and use all the power yourself.
Installation cost is about £1000 per kw.
I have a system that heats my hot water when I start to generate more than I using.
Also worth noting that cheap overnight electricity is likely to disappear at some point, as the grid supply/demand equations change with changing generation/use modes.
I did the maths a few weeks back and break even was also around 20 years (at about the time the solar panels may then need replacing!)
Most of my energy money goes on Gas so even for the lesser amount of electric it wasn't viable
Payback times depend massively on your usage patterns, if you are out all day at work then you're not going to get as much benefit. The OP usage patterns sound a-typical and they would likely see more benefit from solar panels. Impossible to say without knowing any more details.
However the economic viability of solar isn't what was asked. They wanted installer advice, of which I have none (I did install some on a campervan!), so I'm out.
If you go the diy route n& arent bothered about FIT & MCS sign off, this system which i think is 2kWP is £1600.
You are limited to a 3.7kw installation on a single phase domestic supply.
Almost. You are entitled to 3.68kW on a single phase connection (16A per phase at 230V/400V) - you just have to tell the local DNO.
If you want more then that may be possible, but you need to ask and there may be design fees.
Also you may be able to fit a larger solar generation installation and an export limiter (G100) that keeps export to 3.68kW but that varies by DNO I think.
MOS
something like that interests me - i have a large 40degree due south facing roof.
the sums dont add up for me to be paying mega bucks(last quote i had was over 8k for a 4k system) to have one installed because i live at 57.2 so generation hours are reasonable low in winter when im likely to want electric. but it would be good to get some self generation on the go to offset the fact i have to use oil for heating - Id consider fitting a heat store and using a PV dump into the immersion if i had solar capacity.
PV watts reckons i might optimistically see 3300kwh a year from a 4kw system.
I've seen a few kits that are sold as *plug in* and connect up to fused spurs - - 2 required for 4kw - I'm just curious how this works in the real world - how does this not end up like when you jimmy rig(double male plug) a generator into the ringmain without isolating from the incoming mains - Ie against the law and not good for safety of the workers etc....Obviously a sparky would be doing this part - im just talking about me doing the donkey work getting it all on the roof and fed in.
IT just strikes me as a bit dodgy selling it as a "plug in kit"
That defiantly sounds dodgy!
hey ive not looked into the specifics - its just they way they were trying to sell it rung alarm bells.
the worrying part is - i just about know enough to question it.
there will be people who dont and fire it in.
They include a "plug in solar connector unit".
Not sure what that is?
However, my system has an isolation switch downstairs, next to my consumer unit and a box upstairs next to the inverters for the connection to the ring main.
Genuine question - How is that different from connecting directly into the ring main at a plug socket? I don't mean from a regulation point of view but from a practical POV? What risk does that pose?
IANAE!
That defiantly sounds dodgy!
Never use a defiantly dodgy builder.
I keep looking into it. I cant make it worthwhile financially. Which is a shame.
install for free then fleece you the feed-in tariff
Feed-in is now officially dead. The replacement thing, SEG doesn't guarantee that you'll get much of anything for your exported electric, unless your electric company is generous.
Which reckons [SEG article here] you'll save £300 a year. In our house that's looking like a 20 year payback, just to get back to zero.
I did some calcs for my situation-
My use;
about 7200 units, 0.15p/unit, £1080/year.
Solar;
£7k for average 4kw ish install (source, googled it)
generated units, 2800/year (source, google, assumes I can use them all, assumes south facing, assumes nothing ever goes wrong, etc)
savings/year, £420
7000/420 = 17
I'm definitely out.
Any merit financially for folks running electric cars? Solar daytime charge of a battery bank, then vehicle charge from the battery overnight? I’m guessing it would be an expensive set up judging by the Tesla powerwall cost quoted above.
Powerwall adds £7k to your cost. Your call.
Personally, it feels like the new "I'm saving money by installing a woodburner".
currently finite life makes me very wary of batteries.
As i said the only way i make the numbers break even would be using a heatstore to sink the electric in - as i know i cannot feed in to the grid - the infrastructure off the hill wont take it.
Personally, it feels like the new “I’m saving money by installing a woodburner”.
It all depends on your personal circumstances and your usage.
It sounds like it would be a good fit for the OP, he has a heavy electricity usage 24/7.
So even on a warm, sunny day, he's using a lot of electricity.
For us, we have high electricity consumption due to business requirements during the day and in the summer months, so it makes sense for us. Our payback is less than 10 years.
Don't forget, electricity costs are only going 1 way. It's going to cost a lot more in 10 years than it is now.
If you're actually using the power generated by the solar panels (i.e. your vivariums consume all that they can produce), then I would investigate a cheap DIY build with a transformer plugged directly into the mains.
No need for batteries or FIT if you're using it while it's generated.
300W panels can be had for around £100 now (my 310W all black posh one was only £140).
Start small and see how you go?
The electrics is all pretty simple.
I got all my stuff from Bimble Solar who have all sorts of kits.
e.g. this one:
https://www.bimblesolar.com/ongrid/mains/3kw-grid-ja
thats what im not sure about - how can you have a transformer directly plugged into the mains .
how does that not back feed into the grid if it went "down" as per if you did the same thing with a generator.
It all depends on your personal circumstances and your usage.
Yes, but I've not seen any numbers that suggest solar panels will save money, doubly so if you might possible maybe move house any time in the forthcoming 25 years, even if you don't ever move it looks like a bit of a dubious break even. I'm open to being corrected by reasonable argument.
When the government were paying you to conduct a solar power experiment, it was a different set of sums. Now, they're not.
As for being green, my guess, and I accept it is a guess and am willing to be proven wrong, my guess for what it is worth is that there are probably really rather better value ways to put your money to use on reducing your carbon footprint and outgoing energy spend, instead of paying the Chinese manufacturing sector to dig up and process all those lovely chemicals and rare earth minerals needed to manufacture a solar panel, then burn a load of energy making it, then ship it half way across the planet before finally sticking it on a badly insulated UK rabbit hutch in order to generate "green electric".
Basically, I call shenanigans.
Yes, but I’ve not seen any numbers that suggest solar panels will save money
This is an over simplification and there are other factors, however, the overall principal doesn't change. However, I think that you are right that for most households they don't use enough electricity during the day, in the summer to make the numbers work.
In the case of the OP, from what he has said, he will consume all he produces and he has a high consumption
If you pay £4000 for a 3.7kw system, for it to pay for itself in 10 years, it needs to generate £400 of electricity a year.
A typical cost per kwh is 15p. So about 2700 kwh per year. Which is 7 - 8 kwh pr day. Probably gets nowhere near that in the winter but will easily do that in the summer.
It's only viable for homes with high consumption.
If you pay £4000 for a 3.7kw system, for it to pay for itself in 10 years, it needs to generate £400 of electricity a year.
Every price I've seen quoted on the net says £6k - 8k, for that install. Yes, £400 a year of electric will fall out the panel. That is still 15 or 20 years payback. I contend it is not - currently - viable even for a home with high use.
Yes, panels will get cheaper, and electric will get more expensive.
I'm not sure the cheap panels will every become greener. Chinese panels aren't being made to the same environmental standards as European panels which carry more cost for disposal of unpleasant byproducts. The cheap ones will either have to get more expensive, or stay cheap and continue to result in manufacturer produced pollution.
Still, who's to say what will happen on the generation side of things, or with battery stores. Interesting times.
Every price I’ve seen quoted on the net says £6k – 8k,
That's high. Supply and fit is typically around £1k per Kw.
how does that not back feed into the grid if it went “down” as per if you did the same thing with a generator.
Your panels generate DC, so if you are feeding it into your mains it needs an inverter to make it AC. The inverter will synchronise with the AC waves with the mains. If it can't find any mains to sync with, it cuts out.
I have a generator properly wired in, and that has a 190A changeover switch, ie, the house is fed either from mains or generator and can never be connected to both. A Tesla Powerwall (I don't have one) will apparently feed stored power back into the house if the mains goes off, so it must have some kind of isolator built in.
quoting £6k
If that's typical then prices have gone up quite a bit in the last 3 years.
I paid £12k for a 12kw installation. I got 2 quotes from local installers and they both came up with similar prices. In conversation with them they both said that for a straight forward installation and "dumb" inverters, then £1k per kw was a good guideline.
It is possible to get close to £1k per kw but it will be a very basic system and not recommended if you have any potential shading issues from trees/chimneys/neighbours houses etc.
Any form of shading and it's good practice to use a solaredge or similar setup, you'll be looking more like £6k for a 4kw setup.
I couldn't make the numbers work either, and that was assuming I could do some on the flat part of the roof.
Are you able to turn stuff off or down for a few hours a day? We moved to Octopus Agile, the prices track the wholesale half-hourly prices and it's quite a bit cheaper for most of the day but goes expensive during the 4-7pm peak. We're averaging about 7p a unit overall.
Your panels generate DC, so if you are feeding it into your mains it needs an inverter to make it AC. The inverter will synchronise with the AC waves with the mains. If it can’t find any mains to sync with, it cuts out.
cheers for that , thats the missing link i wasnt getting.
Makes sense now.
thats what im not sure about – how can you have a transformer directly plugged into the mains .
how does that not back feed into the grid if it went “down” as per if you did the same thing with a generator
No it really should have an automatic cutoff switch that disconnects the inverter from the mains (and therefore the grid) as soon as the grid power goes down. Otherwise power is back fed into the grid.
I've recently had a powerwall battery fitted to my 1 bed bungalow by DGHP housing association (galloway) as they accessed grants to do so to try and offset the electrical costs of running an airsorce heat pump/5 radiators that was installed 7 years ago (no mains gas here), To run the Airforce heating/hot water it costs me about £25 week as the house is very poorly insulated, (i use approx 5500kw/year which for a 1bed tiny bungalow is ****ing criminal), nothing under the suspended wooden floor (very draughty), minimal in attic, none in walls so heat escapes as soon as any attempt to put it in. Prior to the airsorce heating being fitted i had an open fire/back boiler which worked fine, house was roasting as it kicked out a helluva heat but that was removed to comply with environmental and green initiative bullshit and fireplace blocked up/chimney capped. Within a few weeks of the airforce heating being installed i opened back up the fireplace and fitted an inline multi fuel stove as the heat pump was/is utter shite at actually providing noticible heat through radiators.
My electrical supplier is now octopus energy agile tariff so it charges up the battery at night when the costs are between 6-7 p/kWh and discharges/powers house/airsource heating during the day when the p/kWh costs rise, only had the battery a week so far so it'll take time to see if it makes much difference to costs but as i didn't pay for it then any saving will be a bonus. Id much rather the housing association spent money on bringing the 30yr old bungalow up to modern insulation standards but they refuse to do so, most likely if they insulate my house then they'll have to insulate every house fitted with an air source heating system.
A mate has built rather large 4 bed house and his air source heating (daikin altherma same as mine) is brilliant with his underfloor heating as house is super well insulated (not quite passive but not far off it) and stupidly cheap to run (he's also got solar/powerwall battery) so it's obvious fitting an airsorce to an old draughty house is ****ing pointless but DGHP will not listen.
I'll try and get some details from my mate regarding his house/solar/powerwall set-up and report back
Anyway....at least i can pretend to own a tesla when i use the fancy tesla app on my iPhone to check my powerwall battery status.
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battery
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Tesla gateway controller
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utterly pointless airsource heat pump that breaks down on a fortnightly basis
the heat pump was/is utter shite at actually providing noticible heat through radiators.
*facepalm*
Not sure what's more criminal, the cost of heating your house or the utter ineptitude of the Housing Association.
We have those at Daikin units at work, they're not great in heating mode (well they are but frequently, as said, break down).
Breaking down you say?, over the previous 7 years It’s broke down/failed to provide heating or hot water on 40+ occasions, so that’s 40 times I’ve had to phone up for an engineer to come out and repair it. Not having a reliable heating/hot water system is rather annoying, especially for myself with secondary progressive multiple sclerosis which is particularly sensitive to cold leading to my muscles going into spasm and locking solid (uhtoffs syndrome), had the engineer back out earlier today to repair as the heating system dropped its guts/vented all the hot water last night, got up this morning and my house was 13.5 dg ☹️, on top of a current kidney infection it’s not conducive to health
Could be worse.£5000 a year electricity bills for some Falkirk council house tenents.
That’s hellish, thought I was in a bad way energy wise but that is criminal. A council up near to Inverness fitted 160 (approx) airsource heat pumps to unsuitable properties not on gas main a number of years ago but had to remove them as costs were too high, I’m considering paying for an in-depth independent housing/insulation/heating report to be done so I could present it to DGHP and force them to take action, dunno if they’d acknowledge it though and I’d then be £400-£500 out of pocket.
Your panels generate DC, so if you are feeding it into your mains it needs an inverter to make it AC. The inverter will synchronise with the AC waves with the mains. If it can’t find any mains to sync with, it cuts out.
Please don’t do this. It may cut out. Equally, and I know this both from personal experience of customer installations and documented cases in the industry, it may not.
The capacitance and inductance in the electricity network means it will resonate at some frequency, however the resistance tends to damp this out. Add a power source though and it will run.
It’s called self-excitation, and although more commonly associated with asynchronous induction generation, is part of the reason that G83 or G98 calls for over/under voltage and over/under frequency protection plus loss of mains.
One installation, nominally 230V 50Hz, was as I recall found running at 420V 75Hz.
Equally someone may plug in a Honda generator that provides a 50 Hz signal. They shouldn’t, but...
Of course you may be fine.
But still don’t do it.
I want solar as I think the government should invest motte in renewables.
As I have resigned from this country it’s up to me to do it myself. Also I would like my own electricity for when I the system crashes / the Russians decide to turn us off.
Please don’t do this
Don't do what? I wasn't suggesting anyone does anything, just describing what happens if you have solar panels that are configured to sync with the mains, rather than being free standing, which was what I thought the context of the question was. If my description is incorrect, apologies and please explain. I can see in hindsight that it might have been taken to refer to trying to DiY rig free-standing panels to feed back into the grid - in which case I definitely agree, don't do it.
Fair enough.
All I was saying is if you are syncing with the mains, make sure you have the relevant protection fitted, don’t rely on the lack of mains commutation of the inverter as stopping the panels feeding the mains.
As for why they might output power, well depending on the design and what protections are built into the inverter and what else is connected to the mains a variety of things might happen.
It all works as a system and looking at one component in isolation is no guarantee of what will actually happen.
It all works as a system and looking at one component in isolation is no guarantee of what will actually happen.
Thanks. Yes, I was referring to the system I have works, as far as I understand it - and I assume other systems are the same. I'd assumed that the reason the inverter isolates itself on loss of mains was a protective measure not fortuitous, but I'm a civil engineer not electrical so don't know the detail!
You probably have a correctly installed solar generator.
Unfortunately not all are.
And equally unfortunately as soon as one installation is connected to our network it becomes part of a wider system of components that includes what your neighbour has installed and the residual bits of our network on your side of our disconnection point. It all gets messy.
And you’d be amazed how many people with those little Honda generators think a bit of flex with a 13A plug at both ends can be used to keep their lights on during a power cut. Not a good idea.
Apologies that you’ve ended up on the end of 28 years worth of rant.
Feed-in is now officially dead. The replacement thing, SEG doesn’t guarantee that you’ll get much of anything for your exported electric, unless your electric company is generous.
This. The lack of subsidy has torpedoed the economics for domestic solar PV.
For those interested in typical generation these are the monthly figures for our 4KWh system near Chester.
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It's a 50:50 split East/West which actually has hidden benefits in that in the main 6 months it will start generating earlier in the morning an finish generating later in the evening compared to a South facing system.
This actually gives you more usable power as you don't have quite the same peak in the middle of the day when you are less likely to be using that power.
Overall an E/W aspect doesn't produce a lot less than a South facing system, and seeing it still producing decent numbers at 8pm is pretty cool!
Hadn't thought about usefulness of East West split before 🤔, always been envious of neighbours due south roof calling out for solar.
Hadn’t thought about usefulness of East West split before 🤔, always been envious of neighbours due south roof calling out for solar.
Don't be, you can be using your own generation well after they've started importing power.
We also have a 3KWh system in N Wales which faces due south. This is a 'perfect' days generation (for the middle of September):
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As you can see it's pretty much done by just after 5pm
By comparison this is our E/W system at home the following day (not so sunny but still illustrates the point) and you can see that it's still generating well after the South facing system has packing in for the day:
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So don't discount an E/W facing aspect.... it has its benefits!!
Cheers Sharkbait 👍
