Free solar panel discussion

Nang

Cardew wrote: »

That of course is what myself and others have been 'preaching' ever since the 'rent a roof' schemes were introduced. We have posted many times about the probability of PV generated power used in the house being much lower than people hope.

The problem is that in many cases you are unlikely to get objective posts from people who have taken the plunge and rented their roof.

This is a good example for someone who has paid £500 for the privilege of renting his roof for installation of a 2.8kWp system:



Willing to offer advice as well - about a system that appears to be producing about 7,000kWh a year.

The problem is that he believes(or wants to believe) his figures are reasonable, and other people will believe him.

A house is advertised for sale with an ASG(3.3kWp) system on the roof and the blurb talks about £400 a year savings.

Contrast that with mcifi5 who has had a system for over 2 years, has a wife and 2 children at home all day, and uses about 500kWh a year.

Nice post Cardew

The truth is I have seen these kinds of figures thrown about as well and after experiencing the system 1st hand, I believe them to be well inflated, and therefore misleading. Also When you also consider the risk of to a home owner of renting your roof out (resale, damage to property etc), I want to get to the truth.

I guess what I was trying to do was to get an accurate figure on real cost savings as opposed to a snap shot on how much of their own PV elect someone used in a year.

Shame, it sounds like this might be unobtainable.

John_Pierpoint

Nang wrote: »

Apologies for potentially reopening a can of worms ..............
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In fact, I'm currently sitting in the cold, as our combi boiler has broken down, despite only being one year old.:(

Yes we have been round this loop lots of times.
There is a gizmo called an EMMA, but it is not economic to buy it when the grid is so cheap.
The only sensible thing to do with the spare day time electricity is:
1. Sell it to the grid for 3p and buy it back again at say 10p, thus using the grid as a battery.
2. Use it to charge up a battery system (might work if you had a small forklift on night shift).
3. Save it as heat BUT most electrical heating devices for hot water (who needs space heating in the summer?) take 3KW so there is a danger of sucking some of this off the grid. (I have suggested a small kettle element - someone do the physics: how much water could one heat from say 15 degrees to 65 degrees with 1KW input for 6 hours?)

As the PV panels and the inverter work by raising the AC voltage so that it goes "backwards" into the grid, I am surprised that it is expensive to invent a switch that turns on according the the voltage on offer.

What make of Combi is it?

Was the system flushed until it sparkled when it and its "corrugated cardboard" heat exchanger were installed?

grahamc2003

Nang wrote: »

Graham

Apologies for potentially reopening a can of worms here, but what about if:-

When they installed the system, they installed a relay that only switched on the immersion heater when there was enough PV power available for it. Would this not save money for the home owner? As you would be generating hot water through the cheap / free, elect and not by burning the gas.

I also considered there might be an additional reliability benefit (for sunny period) as the panels have no moving parts.

I have had nothing but bad experiences with combi boilers, they seem to be unbelievably unreliable, perhaps even more so than the British weather

In fact, I'm currently sitting in the cold, as our combi boiler has broken down, despite only being one year old.:(

Well, now you know why I prefer an all electric house (supplemented by a wood burning stove in the main room and an oil fired AGA in the kitchen). Although electric heating on E7 is undoubtably more expensive than gas, I've always valued the lack of gas boiler engineers at our place, the lack of water circulating almost everywhere, and the lack of regular boiler replacements. Take that lot into account, and I expect electricity is cheaper (though admittedly less flexible).

Regarding the control of the pv electricity - we know everything necessary to use the pv very efficiently, i.e. switching in and out load in real-time to match pv generation. I think it was mentioned earlier in this thread (good luck searching!) that such control equipment is available (however, when I read it some weeks ago, I'm not sure it was designed for domestic applications). Using such equipment would ensure a very high percentage of the pv generation was used (if implemented correctly).

The catch, iirc, is that the equipment is, or would be, too expensive to justify, with probably a payback period several times the panel life.

Nang

John_Pierpoint wrote: »

Yes we have been round this loop lots of times.
There is a gizmo called an EMMA, but it is not economic to buy it when the grid is so cheap.
The only sensible thing to do with the spare day time electricity is:
1. Sell it to the grid for 3p and buy it back again at say 10p, thus using the grid as a battery.
2. Use it to charge up a battery system (might work if you had a small forklift on night shift).
3. Save it as heat BUT most electrical heating devices for hot water (who needs space heating in the summer?) take 3KW so there is a danger of sucking some of this off the grid. (I have suggested a small kettle element - someone do the physics: how much water could one heat from say 15 degrees to 65 degrees with 1KW input for 6 hours?)

As the PV panels and the inverter work by raising the AC voltage so that it goes "backwards" into the grid, I am surprised that it is expensive to invent a switch that turns on according the the voltage on offer.

What make of Combi is it?

Was the system flushed until it sparkled when it and its "corrugated cardboard" heat exchanger were installed?

This one is a "Baxi", but the ones we had in the last two houses were "Ideal" and they were truly dreadful.

I'm not sure about the flushing as the house is only 1 year old and the builders installed it.

It's being fixed under warranty but not until Tues. After that I have a British Gas guy coming to service it, so I hoping he might do a proper check on the builders work, is this realistic?

zarazara

what happens if,say,5 or 10 years or so after installation something goes wrong ith the roof,say slates damaged and blown off in high wind and/or partial collapse? who pays for the panel damage and renewal?

Nang

grahamc2003 wrote: »

Well, now you know why I prefer an all electric house (supplemented by a wood burning stove in the main room and an oil fired AGA in the kitchen). Although electric heating on E7 is undoubtably more expensive than gas, I've always valued the lack of gas boiler engineers at our place, the lack of water circulating almost everywhere, and the lack of regular boiler replacements. Take that lot into account, and I expect electricity is cheaper (though admittedly less flexible).

Regarding the control of the pv electricity - we know everything necessary to use the pv very efficiently, i.e. switching in and out load in real-time to match pv generation. I think it was mentioned earlier in this thread (good luck searching!) that such control equipment is available (however, when I read it some weeks ago, I'm not sure it was designed for domestic applications). Using such equipment would ensure a very high percentage of the pv generation was used (if implemented correctly).

The catch, iirc, is that the equipment is, or would be, too expensive to justify, with probably a payback period several times the panel life.

Great reply thanks

then I guess this type of thing might be more realistic when its price comes down in the future.

In the mean time though I am right in assuming that it's worth switching on the immersion heater if there is enough spare PV power above the houses background consumption (fridges etc) to cover it?

Nang

zarazara wrote: »

what happens if,say,5 or 10 years or so after installation something goes wrong ith the roof,say slates damaged and blown off in high wind and/or partial collapse? who pays for the panel damage and renewal?

Hi is this in reply to another quote or in reply to the main thread please?

If in reply to the main thread, I don't know what it says in the contract of all of the companies that do this, but for ASG their contract (or agreement as they call it) says that you can have the panels removed up to 2 times a year to have maintenance or repairs done on your roof, at no cost.

Interesting enough though, this was one of the things about the contract that appeared to be too vague and therefore made me nervous. i.e what happens if you need to remove them 5 or 6 times, do you have to pay for the last 3 and 4 times?

Cardew

John_Pierpoint wrote: »

As the PV panels and the inverter work by raising the AC voltage so that it goes "backwards" into the grid, I am surprised that it is expensive to invent a switch that turns on according the the voltage on offer.

Without getting too technical, the AC voltage is not the issue.

The inverter will produce 240v AC, the crucial issue is how much power it can deliver at that voltage.

An inverter might only be capable of supplying 0.5 amps @ 240v at one particular time, but 10+ amps at another time.

The difficulty is to match the power available to the required task.

My radio uses 12v supplied by eight 1.5v AAA batteries, but they don't provide enough power to start my car;)

Nang

Nang wrote: »

Some people have sussed that they will only get 3p for there elect if they export or that there power companies will assume they will only use 1/2 of what they make(this is what they do with the ones of us that dont have the export meters). But if they use it they can save 9p (or more in the latter) so obviously they are changing their habits.

Just checking back through my posts and I noticed this was a sentence that caused loads of confusion.

Don't want to go over old ground here but it occurred to me from the responses to it, that people might not be aware of how the FIT Payments work. So I thought it may be helpful to explain:-

Provided you get your panels installed by an MGS (micro generation Scheme) accredited installer you can ask your power supplier to go on to their MGS scheme.

They send you a form to fill in (mainly for your installation number) but that's it, fairly straightforward.

The power companies ask you for your fits payments quarterly (End of March, June,Sept, Dec), and you have to tell them the figure from the generation meter and the date you noted it.

Unless you have an export meter (which as far as I'm aware most people don't on these new installs) this concept of 3 pence for what you export doesn't really exist, as your power company will just pay you an additional 1.5 pence on every Kwh you generate. They do this as they will assume that you will use 1/2 of all the electric you generate, and then calculate your payment accordingly.

The net result is that, if you are eligible for the 41.3 pence FIT you actually get 42.8 pence to cover your FITS and export payment.

The reason this is relevant is, they will pay you this amount regardless of how much of your own PV electric that you use. Therefore there is a fairly high incentive for the thrifty home owner to use that PV electric rather than let it go back on the grid.

Feel welcome to come back to me if this post needs to be clearer.

grahamc2003

Nang, there has been no misunderstanding due to the people replying to your posts not being (and have been since they were formed) fully aware of the fit subsidy system..