Free solar panel discussion

Cardew

John_Pierpoint wrote: »

There is a thread on here somewhere all about getting experimental refrigeration for free so, in exchange for allowing the technicians to remotely monitor how it is used by a cross section of the market.

John,

I have such a sytem in a property I own in the USA.

I am paid an annual fee(a reduction on my electricity bill) for allowing some heavy consumption items(aircon, water heater) to have their power cut off for very short periods - minutes.

The idea is, at times of heavy load on the grid, to be able to reduce the instant demand by disconnecting a lot of power hungry appliances. They choose non-critical appliances.

At the moment in UK we have can have a peak demand of around 60,000MW and we must have the Generating capacity to meet that demand. (it is 41,653MW at this instant). It would be perfectly possible to disconnect a few million fridges/freezers/immersion heaters etc and reduce demand by a few MW and we wouldn't even notice!

grahamc2003

Pincher wrote: »

If it costs 2p in fossil fuel to generate 1kWh of electricity at noon, it still costs 2p at 3am.

Behaviour change is easy. Make ALL tariffs Economy 7!
Charge 7p off-peak and 10p peak, instead of 5/13p.
I am assuming 7p is break even, so the supplier doesn't lose money at night, so there is no need to bump up the price during the day.

.

Not sure of your first point. The cheapest generation is used to satisfy the demand for each half hour. The cheapest will usually be scheduled all the time they are prepared to generate, the more expensive only get scheduled when there is no cheaper available. Hence, at low demand, the cheapest run, at high demand, the marginal cost steps high and higher as more and more higher cost generators are scheduled.

As to altering behaviour - yeah, variable tariffs do that. But even with E7 much more generous than you say (mine is 50% of the day rate, and it used to be 33% of the day rate), not all that many people take it up. If E7 reflected the cost, then the differential would be higher (say 20% of the day rate), and more would take it up. In fact, increasing the differential between day and night prices would be far cheaper and environmentally beneficial than subsidising windmills and PV, which have only minor environmental effects.

The way to look at it is to ask if whatever is proposed actually contribute to, or cuts down, peak demand (hence reduces the need for new/replacent stations). If yes (like E7) then there are likely major benefits, if no (like windmills and PV) then at best there can only be minor benefits. Strange thing is, the major benefits (e7) can be realised at a very low cost, where the minor benefits (windmills and PV) are very expensive indeed.

Jon_Tiffany

HanSpan wrote: »

This seems to be the most important question if you are considering one of the free systems (far less important if you are going for purchasing yourself). I've read all 50 pages and it took a while but I think I now understand how it works and just can't see how its ever likely to get anywhere close to 50% use. I'd got all excited about the idea of applying but am now thinking not so much!

Someone please tell me if I have this wrong but as I understand it, because you can't store the power, whether its going out or coming in is on an instant by instant basis. So to me it seems there might be lots of time where you are using a part to all of what you are generating, but far more time when you are having to draw all or some back from the grid.
(I'm using made up numbers and 'thingies' rather than kw... so as not to fall foul of using the wrong type of units or the potential output of various systems)

Its 12:00 on a sunny day:
generating 4 thingies & using 1 thingy doing nothing much = 3 thingies back to the grid (using 25% generated, feeding back 75%)

12:02 turn on the kettle
generating 4 thingies & using 6 thingies = 2 thingies FROM to the grid (using 100% generated plus taking 50% more from the grid)

17:00
generating 2 thingies & using 1 thingy doing nothing much = 1 thingy back to the grid (using 50% generated, feeding back 50%)


17:02 turn on the kettle
generating 2 thingies & using 6 thingies = 4 thingies FROM the grid (using 100% generated plus taking 400% more from the grid)

22:00 (kettle on or off!)
generating 0 thingies & using 1-6 thingies = 1-6 thingies FROM to the grid (taking 100% from the grid)


To do the maths for every second of all 365 days of the year and all the things you can switch on and off is not something I fancy trying but my gut feeling is you'd be lucky to use 25% of what you generate, probably much less. So you are still going to have to pay at least 75% of your normal electricity bill even if you generated exactly as much over a year as you use (not likely?).

I'd be really interested to know, from anyone who has a system installed and does NOT have a backward running meter (which changes all this but can't be relied on so I'm not factoring in) how much power they took per month before, and how much they take now.

footnote - allthough the thingies are made up I think I have the factors about right - I have en eco-eye attached to my meter and its goes from showing about £1.50hr at 'resting' to about £10 with the kettle on (1:6ish), and from earlier posts it sounds like a kettle on uses about 1.5 times as much as you'd generate at noon on a sunny day (4:6).

There is one major factor missing - your background usage.

For example, if your background usage is 3kW and you have a 2kWp solar system, you will use 100% of the generated electrcity.

If your background usage is low (out at work, nothing left on) then you are not going to get to use much.

I have a small solar pv system and my background usage is quite high. For the last month I estimate that I have used around 80% of the electricity.

If I had a larger system, like others have said I doubt that I would I would be able to make much use of the additional leccy.

How much electricity you use is going to vary wildly between different households.

I would put myself at the high end of the scale at 80%, others may only use around 20%.

ninjaryder

Jon_Tiffany wrote: »

There is one major factor missing - your background usage.

For example, if your background usage is 3kW and you have a 2kWp solar system, you will use 100% of the generated electrcity.

If your background usage is low (out at work, nothing left on) then you are not going to get to use much.

I have a small solar pv system and my background usage is quite high. For the last month I estimate that I have used around 80% of the electricity.

If I had a larger system, like others have said I doubt that I would I would be able to make much use of the additional leccy.

How much electricity you use is going to vary wildly between different households.

I would put myself at the high end of the scale at 80%, others may only use around 20%.

Hi i have had a 2.3kw system fitted , i live on my own work 3 1/2 days a week on average in the 5 weeks since fitting i have generated 212 kwh and have used 208 kwh of it on my normal meter.So i am quite happy to be 'asumed' to be returning 50% to the grid.My only small gripe is my storage heaters are on a different circuit and meter and would like some device to 'switch' between circuits as demand deemed neccesary.

Pincher

grahamc2003 wrote: »

Not sure of your first point. The cheapest generation is used to satisfy the demand for each half hour. The cheapest will usually be scheduled all the time they are prepared to generate, the more expensive only get scheduled when there is no cheaper available. Hence, at low demand, the cheapest run, at high demand, the marginal cost steps high and higher as more and more higher cost generators are scheduled.

As far as I know, gas/coal/oil fired (fossil fuel) ARE the cheapest to run. Depending on the price of oil and gas, I suppose they would prioritise accordingly amongst these.
I think French nuclear is subsidised in some funny way, so they are more competitive than English ones. I suppose wind will be cheapest, since there is no fuel cost.

Pincher

Cardew wrote: »

I have such a sytem in a property I own in the USA.

I am paid an annual fee(a reduction on my electricity bill) for allowing some heavy consumption items(aircon, water heater) to have their power cut off for very short periods - minutes.

The idea is, at times of heavy load on the grid, to be able to reduce the instant demand by disconnecting a lot of power hungry appliances. They choose non-critical appliances.

During last winter, we had ten days of fuel left in the UK,
and we suddenly found out there are preferential rates for businesses that are willing to forego power when there's a shortage. Apparently it's done by phone, and they rotate the outage.

They told us not to worry, there's plenty to go round.
So obviously I went out to get 15kg of butane rightaway.:rotfl:

HanSpan

Cardew wrote: »

HanSpan.

The big factor that you haven't considered is the size of your system - and hence output.

Taking silly examples, firstly that you had one 125Wp panel(generates a max of about one eight of a thingy!!) on your roof(I know you don't get FIT for that size) you would have no difficulty in using 100% of the generated power. Put a 20kWp system on your roof(20 thingys!) and you will be lucky to use 10%.

This has been discussed in the green forum and there are a couple of people posting (yakky58 and mcfi5) who have had systems for a couple of years and have export meters so know exactly how much they generate in the house i.e. they know what the panels produce and what they export, so consumption in house is known.

Mcfi5, who is a solar enthusiast, has a small system. He has a wife and small children who are home all day and 'works' at using as much electricity from the panels as possible. He uses approx 500kWh per year in the house - so a saving of £40 to £50 a year. He is of the opinion that if he had a 4kWp system(the largest for max FIT) he wouldn't be able to use much more than 500kWh a year.

The regulations allow an assumption of 50% of generated electricity to be claimed as exported if you don't have a export meter - which seems about right for small systems from the evidence I have seen on line.

I had sort of based my numbers on the 2-3ishkWp systems that seem to be what is contemplated under these free schemes (by using the factor of generating 4thingies, using 6thingies for a kettle) but I see exactly what you mean.

In terms of the poster who uses kWh per year from his system - is that half (ish) of what his system produces, with all his working at it, or less? (sorry I really can't face finding another thread and reading 50 or so more pages

I'm finding this all fascinating but its pretty much convinced me not to bother applying for a freebie. 25 yrs of something on my roof that MAY put off buyers for probably less than £40 a year (we're not home all day) off my £800 per year electricity bill just doesn't seem worth it. Maybe if they offered to give me the feedback 3p per unit and they kept the FIT I'd be more tempted as I'd get something for all of what I generated, actually even then not so much as I think that would be a trivial amount.

I wonder if people applying realise how little they are likely to save, I'll be really curious to see what happens when people have had these for a year.

HanSpan

Jon_Tiffany wrote: »

There is one major factor missing - your background usage.

For example, if your background usage is 3kW and you have a 2kWp solar system, you will use 100% of the generated electrcity.

If your background usage is low (out at work, nothing left on) then you are not going to get to use much.

I have a small solar pv system and my background usage is quite high. For the last month I estimate that I have used around 80% of the electricity.

If I had a larger system, like others have said I doubt that I would I would be able to make much use of the additional leccy.

How much electricity you use is going to vary wildly between different households.

I would put myself at the high end of the scale at 80%, others may only use around 20%.

I sort of had considered it, using a very backwards method;) My thingies were based on what my eco eye says at rest vs with the kettle on. I can actually turn my ecoeye from £ per hr to kw and the background rate (what I've been calling "at rest") shows about .6kw-.75kw. This doesn't change much with the telly on or a few low energy lights but jumps to nearly 4 with the kettle on.

We use around 8000kw per yr at a cost of about £700 (sorry last post said £800 which it was till I switched again a few weeks ago). I thought we were quite high users and although we're not home all day we do tend to do most washing, drying etc during the day at the weekend but I still can't see how we'd use 50% even if we were home all day and did even all our cooking during daylight hours (not terribly practical!) as our background rate is so much lower than the output of a 2-3kw system (at peak - I realise it will go down to nothing overnight). None of my business (so feel free to say so) but I'm curious about your background rate and annual consumption.

I suppose what I'm realy curious abuot is how much the average person could save off their bills if they took a free system, and whether my suspicion that the potential £100 off annual bills is way over what is likely to happen.

HanSpan

ninjaryder wrote: »

Hi i have had a 2.3kw system fitted , i live on my own work 3 1/2 days a week on average in the 5 weeks since fitting i have generated 212 kwh and have used 208 kwh of it on my normal meter.So i am quite happy to be 'asumed' to be returning 50% to the grid.My only small gripe is my storage heaters are on a different circuit and meter and would like some device to 'switch' between circuits as demand deemed neccesary.

I'm sorry if I've got this backwards but are you saying your normal electricity meter shows you've used 208? Doesn't that actually show what you've drawn from the grid? If so I think you've used 208 that you'll pay for, plus some that you've generated. The 212 generated would have gone some to your usage and some back to the grid and I don't think, without a meter to show what you've fed back separate from your normal meter, that you can tell how much you've used of your own electricity.

As far as I can work out, if I were to have one fitted without a meter specifically showing what I fed back (thus by subtraction what I'd used of my own) the only way to estimate would be to compare with what I took from the grid before I had the solar panels. I'm a bit sad and have fairly comprehensive figures of the gas and electricity I've used over several years so I could do that. I imagine most people have a life and don't keep comprehensive records of units used, so will only be able to guess based on their bills which will be particularly innacurate with the fluctuating, complicated tarifs.

Lifeless person off to read my meters again

Larnsky

HanSpan wrote: »

I had sort of based my numbers on the 2-3ishkWp systems that seem to be what is contemplated under these free schemes (by using the factor of generating 4thingies, using 6thingies for a kettle) but I see exactly what you mean.

In terms of the poster who uses kWh per year from his system - is that half (ish) of what his system produces, with all his working at it, or less? (sorry I really can't face finding another thread and reading 50 or so more pages

I'm finding this all fascinating but its pretty much convinced me not to bother applying for a freebie. 25 yrs of something on my roof that MAY put off buyers for probably less than £40 a year (we're not home all day) off my £800 per year electricity bill just doesn't seem worth it. Maybe if they offered to give me the feedback 3p per unit and they kept the FIT I'd be more tempted as I'd get something for all of what I generated, actually even then not so much as I think that would be a trivial amount.

I wonder if people applying realise how little they are likely to save, I'll be really curious to see what happens when people have had these for a year.

But how many buyers do you generally think would be put off by a free system already on the roof. I have to be honest if I was buying a house it would probably attract me towards the house as opposed to put me off. Unless as I have said previously I was specifically going out to find a house that I could put solar on. The FiT rate is due to be reviewed in April 2012, no one knows which way it's going to go but I have a hunch it won't go up and is pretty likely to go down. Based on this after April 2012 the systems might not be as appealing as the pay off could be even longer so the point of people being put off due to a free system being on the roof might be irrelevant.

The problem I'm facing is that there are a few people on these forums who say that they would be put off if a free system was on the roof, however everyone I know who I've spoken to about it love the idea of a free system and agree with me that it would be a benefit to a house not a negative.