Which free solar provider?

K4blades

Cardew wrote: »

What you need to appreciate is that a cloud passing over will drop the output dramatically. Lots of days the panels will produce no electricity.

Cardew, you don't half talk rubbish sometimes. There must be lots and lots of people on here now who have PVs....I don't think you are one of them Cardew. Can I ask if anyone who has a system if / how many days they have, when they produce no electricity.

The worse day I have had in the past 12 months is 1kwh, and that has only happened once.

Cardew

I suggest you read:
https://forums.moneysavingexpert.com/discussion/2955406

Hello again Jon. I will try and post a picture next weekend. It is too dark now and work is quite busy this week so I will probably not see my house in the light! My estimated output is 3301Kw . (where does the 1kw on the end come from???) So far we have produced 75Kw with somedays making nothing at all. Obviously not the best time of year to be starting.

Our 2.22kwp system has produced 4 kwh today, bringing our January generation (in 16 days) up to 25kWh so far.
We had our system installed on 23rd October and geneated 77 kWh in November and 50kWh in December.

Plenty of people on the internet have their daily output available.

K4blades

Good link, thanks.

I suggest everyone reads it. I can honestly say I haven't read every page, but not much evidence of people saying they have generated NONE, and certainly not for LOTS of days. Quite the opposite, people saying that they have generated X even on dark dull days. There may be a few days in the depths of winter when very little is generated but that doesn't equate to LOTS of days when viewed over 12 months.

K4blades

Cardew wrote: »

If you use an immersion you are only saving the cost of gas at 3p -4p a kWh.

Also it is absolutely certain that you will at times be losing money by trying to use the immersion. Several posts on this but an immersion is 3kW which panels only rarely achieve. So your immersion will be using mains electricity(at 10p/kWh) to top up your generated power.

But do the maths:
If you have a system of 3.3peak or above you can generally expect at least 2.75+ into the house under good conditions.
No-one as far as I know is suggesting using an immersion all the time, but under certain conditions.
In the summer months, and if you have nothing else on, so for example while you are out, maybe using a timer on the immersion, ideally over lunchtime.
Your immersion + back ground will be about 3.25(or you could fit a smaller back-up immersion), of which 2.75 will be from the roof, meaning you pay 0.5 x 10p = 5p.

However, if you prefer to use your gas boiler under the same conditions, then the PVs only need to cover your background electricity, which will be slightly higher due to your central heating pump running, so maybe .3, which of course costs you nothing, and leaves 2.45 exported to the grid.
Now unlike immersions that are 100% efficient, a very good gas boiler is only about 90% efficient maybe much less, so to get the same 3kwhs of heat you need to buy 4kwh, so
4 x 4p = 16p.

That means under the same conditions your gas has cost you 11p more. If you own the system, ie not rent-a-roof, then the export would be subsidised at 2.45 x 3p so you would get back 7.35p, still leaving you on the losing side.

There are a lot of ball park figures here, but there are growing numbers of people who are doing this and finding it works in real life, through experience, but you have to be smart about it. Cardew on the other hand has no direct experience and prefers to find quotes that suit his argument, rejecting all others...so make your own mind up.

celerity

K4Blades, I've debated with Cardew about a few things on these forums, and we don't always agree - but in this case I think he is making a good point.

I have solar PV (and am very happy with it) but he is absolutely right to suggest that trying to run an electric immersion heater is going to be a pain to manage and also not especially cost effective.
Take today for example, as I typed the above I was generating 3.3kW - enough for an immersion. A cloud has just gone over though, bringing me down to 2.5kW. Anyone with panels knows this happens frequently, and will often drop your output down much lower.
Until we have cheap "smart" devices that can detect when they can turn on cheaply, trying to run high powered deviced like heaters manually is only ever going to be practical on completely clear, sunny days - which is when very few of us feel the need for an electric heater!

A "rent a roof" system for people with significant energy needs during the day is obviously more worthwhile than Cardew's average estimates. From monitoring my energy usage on imeasure.org.uk I can clearly see a large dip in the graph when my panels were installed. At the moment I'm saving over £4-5 per week. I'm hoping this will translate to annual savings of around £200 a year but I won't know for definite until I have my first winter. Bear in mind I work from home and there are often 2-3 people in my home office though - that isn't typical daily domestic usage.

/\dam (now only generating 1.6kW )

Cardew

celerity wrote: »

K4Blades, I've debated with Cardew about a few things on these forums, and we don't always agree - but in this case I think he is making a good point.

I have solar PV (and am very happy with it) but he is absolutely right to suggest that trying to run an electric immersion heater is going to be a pain to manage and also not especially cost effective.
Take today for example, as I typed the above I was generating 3.3kW - enough for an immersion. A cloud has just gone over though, bringing me down to 2.5kW. Anyone with panels knows this happens frequently, and will often drop your output down much lower.
Until we have cheap "smart" devices that can detect when they can turn on cheaply, trying to run high powered deviced like heaters manually is only ever going to be practical on completely clear, sunny days - which is when very few of us feel the need for an electric heater!

A "rent a roof" system for people with significant energy needs during the day is obviously more worthwhile than Cardew's average estimates. From monitoring my energy usage on imeasure.org.uk I can clearly see a large dip in the graph when my panels were installed. At the moment I'm saving over £4-5 per week. I'm hoping this will translate to annual savings of around £200 a year but I won't know for definite until I have my first winter. Bear in mind I work from home and there are often 2-3 people in my home office though - that isn't typical daily domestic usage.

/\dam (now only generating 1.6kW )

I do have some evidence for my 'average' estimates.

There are two people who post on MSE who have had PV systems for some time - before FIT's were introduced - and have export meters fitted, so know exactly what they consume in the house.

One uses 1,000kWh pa in the house and the other 500kWh - the latter has wife and two young children at home all day. So in round figures they save £100 & £50 a year.

A director of A Shade Greener(ASG) participated on MSE last year and did not dispute the figure of £100 a year - their valid argument was that £100 was well worth having.

With your atypical consumption pattern - several computers/servers etc used during the working day you will have a much higher 'background' consumption and no doubt £200pa saving is achievable.

On the other hand a house where the occupants are out at work all day might struggle to save £50 pa

Many people need to justify their actions - go on the motoring forum and see those who claim a £10 magnet strapped to the fuel lines of their car reduces fuel consumption by 30%!! -'cos it lines up the molycules(sic)'

Without an export meter it is not possible to know how much is used in the house, so people resort to the 'last year I used £x electricity - this year £y electricity.
Someone posting on MSE with a 'rent a roof' system claimed that it was saving him over £20 a week in electricty bills - every week.

So I think it is perfectly reasonable to put forward the notion that £100 a year saving from a rent a roof system is a good saving.

celerity

Yep, as you say, my daytime usage is atypical - and I still might not do much better than £100 / year (but I hope I do!).

I also agree that £100 per year is still worth having provided you're happy with the potential hassle of getting the work done in the first place. I'm not sure how much trouble it is to sell your house with a FiT scheme either, but that might put some people off.

It's worth noting that each year the savings will go up slightly too, as the cost of electricity rises . So, a canny person might also go for rent-a-roof as a hedge against these rises.

One uses 1,000kWh pa in the house and the other 500kWh - the latter has wife and two young children at home all day. So in round figures they save £100 & £50 a year.

I'm being a bit picky, but for my estimates I use a 12p/kWh cost, not 10p. I am with Eon and they have a rather confusing tariff which I think costs me 15p/kWh for part of the year and then reverts down to 10p/kWh. Based on rough guesses I averaged this to 12p.

/\dam

Cardew

celerity wrote: »

I'm being a bit picky, but for my estimates I use a 12p/kWh cost, not 10p. I am with Eon and they have a rather confusing tariff which I think costs me 15p/kWh for part of the year and then reverts down to 10p/kWh. Based on rough guesses I averaged this to 12p.

/\dam

Likewise with EON.

Don't forget that you will use the first high priced 900kWh pa(Tier 1 units) regardless of any saving from the panels.

e.g. You use, say, 3,000kWh without your panels - which is 900kWh at Tier 1 price and 2,100kWh at the low tier 2 price. Then your panels reduce your consumption to, say, 2,000kWh; so you pay 900kWh at Tier1 and 1,100kWh at tier 2 prices.

Thus you can only use the lower priced Tier 2 units for calculating savings.

Incidentally after discounts I pay 7.38p/kWh(incl VAT) tier 2 price with EON.

bikeman

mmm good debate but it seems to me that solar pv is fundamentally flawed in that a) the cost is only justified with the government FIT and b) output is low when you most need it e.g evenings, winter etc.

Even though I am at home all day perhaps it's still not going to give any real benefit if it cant reduce my gas usage on HW and CH. My elec usage is practically nil during the day.

What a shame that the subsidies haven't been offered to solar farms and business users (or maybe they have?).

I think that once these subsidies get removed/reduced the solar pv will be dead unless it's provided with some form of (battery?) storage.

K4blades

I'm on the same tariff as you Cardew....we must both be very canny with our pennies.

My point about the immersion was that it is down to every individual to find out what best suits their own situation, rather than blankly accepting what they are told. By testing what works best in your own home, you will find that some things do work and others don't.
For example, in the case we are discussing using immersion instead of gas boiler, the savings would be more if your boiler was oil fired or LPG, or even coal fired. You have to work out what works in your own situation. (Whats more, over time, its is widely expected, as seen with the recent price increases, that the difference between gas and elec will get smaller, so the saving being more).

Which takes me onto the next point.....
one of the best ways to find out what you will save from PVs is to have an EPC / SAP calculation done. These are done by independent and impartial assessors, accredited to act in such a way, and not favour any particular commercial organisation.
I have done thousands of these in the past few years and I can tell you that it is quite typical for an average house to save over £200 from PV electricity, without FITs.
This calculation is done using software developed over many years, tested and approved by BRE and CLG, in other words the figures are relatively reliable.

Cardew keeps banding about the £100 mentioned by Sarah at ASG, (I'm not interested in the particular quote or its context), but I also note that it has been mentioned on here that ASG are stating on their website, based on evidence from their customers, that 50% savings are typical.....but Cardew, you rejected this....so how come you want to quote ASG when it suits you, but not believe them when it doesn't. Their website says they have now done about 3000 installations, so thats a bigger body of evidence than the 2 members of this forum that you repeatedly hold up as shining examples. You also, repeatedly question anyone else who posts on this forum their experiences, suggesting that they are mis-calculating.
As the body of evidence grows, your arguments will look increasingly weaker I'm afraid.

Having said that, you must be disappointed that they have just announced massive reductions in the FITs for large scale installations, meaning there will be a greater focus on the domestic side as opposed to factory roofs. Thats politics!