Solar panels for water & heating

pharma

I am looking for advice and opinions on some plans I have around Solar Panels. I already have PV panels that were fitted in July and am fairly happy with them (I would be happier with them if I could accurately match demand with supply or hold onto the power I produce until its needed instead of selling it to the grid for 3p and buying it back 2 minutes later at apx. 4 times the price).

My next project is to look at the solar hot water panels. I have a roof top that faces directly South and there is no shading. I have room for a 40 tube, or maybe even a 60 tube panel if one should exist. I also need a new boiler, as my combi is 10+ years old and is probably fairly inefficient, so am thinking I have an opportunity to some major work on my hot water and heating system. I am really keen to get a new boiler that will take a feed from solar panels and heat hot water and central heating water. I know that there will be dark winter days where I do not produce anywhere near enough water for one, let alone both heating and hot water, but I would just like to capture as much energy as possible.

I have had one company quote me £14,000 to do the whole job, which I thought was quite a lot. Has anyone done the above, or have any opinions on it?

My thoughts (concerns) are -

1. Will the hot water produced by the panels in the day that I would have used for a shower or bath in the evening be used for the early evening central heating forcing me to use gas heated water for the shower later that night? So in reality means I am paying for an expensive bit of kit to redistribute the use of the hot water, but still need to use as much gas, just at a different time of the evening than with a conventional solar hot water system.

2. To have the heating on at 5:30am before the sun rises I will probably have to use gas to heat the water. By heating the water to warm the house in the morning what opportunity does the daytime sun have to heat the water further?

I am really keen to go ahead with this, but am fearful of spending twice the amount I need to on the kit and only really saving an extra £10 a year in doing so.

Any thoughts or comments would be very welcome.

Cheers

albyota

I have solar thermal panels and will be removing them soon to make way for PV, I've had the solar thermal for three years now and would advise against purchasing as you won't get your money back fo 47 years. if you are looking to replace the boiler, I would suggest you consider an air to water heat pump, Like Mitsubishi Ecodan or Sanyo ECO Co2, as you have the PV it will work very well together.
In stead of a normal domestic hot water cylinder connect the heat pump up to a large thermal store, that way you can use it for the central heating as well.

Jon_Tiffany

I have no personal experience of how water panels, but they do work, and work rather well.

Where they fall down is the cost. Thats a huge amount of money to spend to make a small saving, I dread to think how long the payack would be.

I would suggest considering an air source heat pump as suggested above, but even then assuming you have mains gas this doesn't make great sense unless you are reliant on electric for hot water heating.

£14,000 I feel could be much better spent elsewhere, as you already have solar pv there's not much option there.

Is there anything in terms of extra insulation you could consider?

Cardew

Masses of posts in the 'green' forum on MSE about solar thermal.

In essence, in money saving terms they are a complete waste of money.

I don't think people appreciate just how little they save. The Government commissioned tests of 8 systems( including evacuated tube) and the average annual output was approx 1,000kWh; so with gas a saving of appox £45 a year or so, allowing for boiler efficiency. WHICH have also tested.

The RHI scheme may improve this considerably - it will need to!!