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[Vamps]

Anyone got them? they type you buy, not the free 'roof rent' scheme.

It is something I had thought about, anyway a guy came knocking and I have a visit tomorrow from someone to discuss figures etc, they tell me that any surpless will be sold back to the National Grid and I will get paid for this every quarter.

Initial thoughts seem to me is that it will take so long to recoup any expenditure I am unlikely to benefit directly..............

[tunnie]

I have them, came with the house. Fitted during the house build process, ours just do hot water. Whole close has them, apparently around now I can switch the boiler off and just rely on them, the basically circulate anti-freeze up to the pannels. Hot comes down, cold goes up.

I've been using the gas boiler though, not got 100% shall see how well they work. According to others in the close, they work well.

You can get others which do electric too, which you can sell back to the grid.

[Kate]

In a previous house I had free ones off the council and they really helped keep the electricity bills down.

The electricity meter spin thing used to go backwards which was weird.

I would recommend them if the initial outlay isn't too bad.

[Rods2]

I have looked at making my own hot water solar panel at a total cost of a about £500, so the payback time is about 3 years. Somebody that has done this has also published an online diary which shows that during the summer months you can expect all of your hot water from solar and some on sunny days during the winter.

My understanding is the length of payback time when having solar water or solar electricity systems fitted is the (often inflated ) installation cost, plus servicing costs along with exaggerated savings and with solar electricity also the earnings. All of this can lead to a real payback time of 15 to 20 years or more.

I think it is one of those situations where it pays to do some research, get several quotes and work out a conservative payback time. 

[Marks DTM Calib]

If your lucky it might pay back in fifteen to twenty years and thats only because of the over inflated feed in tariffs.

[Kevin Wood]

My parents have solar hot water (only because they needed a new tank and the solar install effectively came free with that).

We have actually set up some monitoring on it to see the real energy output. I think it's fair to say it's some way from providing "all your hot water", except during the hottest few weeks of the summer, where you can get maybe 3 or 4 kWh. It really needs direct sunshine on it for a good few hours a day to achieve anything at all.

So, forget manufacturers claims that it will do something even on overcast days - that's BS, as we would expect.

Their only other options are electric or oil for their hot water, so it's worthwhile, but I'd say if you have gas, it's not worth forking out thousands to have it installed.

[Kate]

Maybe try and find a scheme to get them for free.

[joff]

I have 12 of them on my roof which were fitted free. They were fitted in the July of 2011 and just looked at the meter, in that time they have kicked out over 6800KW and my electric bill has gone down over 50% and it did not cost me a penny

[Marks DTM Calib]

So in 32 months thay have produced 6800kW or around 7kW per day....which is pretty naff.

Plus the free bit will be becuase somebody else is benefiting and will be a 25 year sitting tennant on the roof.....which 'complicates' future sale if a home owner.

[tunnie]

What is reliable way of determining their output? Best I see is the airing cupboard is in-bound & out-bound temp, in the feed to/from the panels.

The solar appears to heat the bottom of the boiler, with gas doing the 'middle' I've yet to be brave enough to kill the gas supply! 

[Kevin Wood]

We put a sensor in water in and out of the solar primary coil in the tank. You then have to estimate the water flow rate and detect if the pump is running. While the pump is running, the temperature difference multiplied by flow rate and specific heat capacity of the water will give you the energy delivered to the tank.

There's normally a little flow gauge on the primary circuit somewhere for diagnostic purposes. We did the sums and checked them against the time to heat the tank (known volume of water and known start and end temperature) and it came out surprisingly accurately.

Thing is, these systems contain all the sensors required to tell you exactly how they are performing on their own control panel - yet they don't! I wonder why?

Oh, and you always heat the bottom of the tank with a solar system, because you are heating the coolest water (that which has just come in from the header tank), and this extracts the most heat from the panels. It also gives you the largest volume of water into which you can put energy - the solar setup can heat the whole tank, making use of the maximum amount of sunlight possible, whereas the gas boiler only heats the top half - it can heat it on demand, so the lost capacity isn't really an issue as long as you've still got enough to run a bath.

[tunnie]

Thanks Kevin 

Be interesting to see when I turn off the gas part, how well it copes. I have a nice big panel, which shows when the pump is running, the temp off the panels ect, but as you say no hard figures on energy generated 

[Sir Tigger KC]

To avoid confusion there are two types of solar panel system.   

Solar PV (photo voltaic) which produce electricity and Solar Thermal which produce hot water.  Tunnie has a Solar Thermal system and I'm assuming that Vamps is looking at a Solar PV system as that's where the sales focus is at the moment, as the subsidies (Feed in tariff) for selling electricity back to the grid are still fairly generous. 

I briefly worked for a solar thermal company as a sales rep and the advice that I'd give is avoid the sort of 'national' company that don't publish their prices and will send a salesman round to give you a quote and a hard sell!!    Many of these companies will disappear and then if you have problems with your system there is no comeback. 

Find a local established supplier who have been around for a few years and will probably be around for a few more.  There's a company round here who advertise in the local paper a 4kw Solar PV system for £5000, which I guess is the base price and may be more depending how challenging your installation is. 

Another thing to think about is the orientation of your house.  If you have a nice big south facing roof which isn't affected by shadows from trees or other buildings then your system will work better than a north facing roof under trees etc.  The salesman may or may not point this out. 

As Mark has said solar voltaic systems are only viable because of the generous subsidies which pay the inflated prices which you receive when you sell your surplus electricity back to the grid.  However, rightly or wrongly that's the situation and it may work out for you that you get a better return on your money than leaving it in the bank.  Remember though that it's not an investment that you can sell on at some point and I think it's unlikely that the value of your house will benefit significantly! 

[chrisgixer]

So in 32 months thay have produced 6800kW or around 7kW per day....which is pretty naff.

Plus the free bit will be becuase somebody else is benefiting and will be a 25 year sitting tennant on the roof.....which 'complicates' future sale if a home owner.

....and in the mean time it can make remortgaging difficult to the home owner, as mortgage companies don't like a third party having an interest in the property. Some lower rates will be unavailable to the home owner due to mortgage products fine print restrictions on solar panels.

Obviously this eats into any savings.

The mortgage company want to see proof of an approved installer.
The mortgage company don't have complete ownership, this can cause them problems for them on repossessions etc. hassles they don't need.

Like lpg on your car, you as an owner need to be sure you'll keep the house long enough to benefit from the out lay. It's no good selling up in a couple of years when you move just to hand that investment to the new owner. You might think that improve re sale value, but not it if they can't get a cheap enough mortgage in the first place.

Re retro fits... Dont do it.

[Sir Tigger KC]

Yes the type of scheme where you get the panels for free basically mean that you've rented your roof to the solar panel company for 25 years in exchange for the electricity produced by the panels.  The supplying company receive the Feed in tariff for the surplus that gets fed back into the grid. 

I'm sure that quite a few people have been stitched up with these schemes by unscrupulous operators.    It may be a good option for some people though.  ie if you're mortgage free and you plan to leave your house in your box!