roof solar panels. Water vs PV

Pep

I want to install solar panels on the roof of my house.

Which is best: water or photovoltaic ?

photovoltaic produce electricity from light, the one you use is simply free, the one you don't use goes into the grid and you are paid.

water panels heat water that you use for bath and/or heating the house.

Both types have cost for installation and maintenance.

Anyone got them? Which is best?

BTW never mind I haven't got a house right now but hopefully I'll buy one in near future...

fleshtuxedo

Haven't got either but I have done some work in that field on a solar PV project for 'one of the UKs leading energy suppliers'.

The viability of any system depends largely on the location and orientation of the house i.e. you want a big south facing roof.

You'll get no real answers before you've chosen a house...

petemadoc

I have water solar panels on my south facing roof.

2 x 20 lots of Exacuated tubes.

They work really well in the summer and ok on dull days too. They don't do anything this time of year because there just isn't enough daylight hours.

The panels heat up a water tank that's 200Ltrs so you get showers and hot water all day or a big deep bath full.

Total cost to me was £1500 for the panels, controllers, pump, and installation. Additional costs are the water tank (I already had) and possible complications getting them on the roof.

Can't comment on PV cells but I know they cost a fortune. Good paypack on the new scheme from the government though.

fleshtuxedo

Typical cost for a 2kW (8 panel) PV system for a typical family house would be c.£7k for kit and installation. That's at cost, so reckon on considerably more for that to you squire. Life is 15-20 years.

PV obviously generates electricity, so you might be able to sell surplus energy back to the grid to help offset the cost.

ilm_zero7

high performance water tubes will give you much better low sun performance and a shorter pay back time than current tech PV's - PV will get better and cheaper but it is too early to buy into the technology domestically unless you want to be seen to have..

andy162

My company installs solar to deliver hot water. We fit Worcester "Greenskies" solar kits. Typical installation costs are £6k. This includes 2x panels, storage cylinder, boiler, pumps & controls(Inc labour + VAT)

The panels have a 10yr guarantee & the boiler has a 5yr.
As regards maintainence you'd be looking at an annual boiler service & a few specific checks on the condition of the solar equipment.

Payback varies, if you anticipate a 30% reduction in your gas bills you'd not be far off. Now there is a rebate scheme whereby the government are paying you for every Kw of energy you produce. This will reduce the payback time also.

Pep

Thanks.

But how do water and PV compare to each other?

surreyxc

As mentioned grant on PV, and if I recall the earlier you do it the more they pay per unit.

However from my own research it seems the pay back on PV is pretty long. Solar water, what about pipes freezing in this weather?

To heat water you could go for geothermal heating, or back boiler on a stove/s. You could probably buy your own little bit of woodland for coppicing for the same price as solar, and it will last longer.

One thing I suspect which has a quicker pay back is water harvesting, and pretty easy to install.

It all depends what house and land you have. My next project I want to be off the grid entirely.

DrewDubya

Assuming correct orientation of house PV offer something like a 9% return on your investment.

With the current grants available you should therefore be able to recoup the cost of your initial investment in 10 to 11 years.

term1te

We had a be nice to the environment day at work recently with a display of solar panels. Basically solar water heating was said to be much more efficient than PV. A good tip was to check if your washing machine or dishwasher (if you have one) will run off hot water. If it does you save the electricity it would have used to heat the water internally. So you save more electricity and have hot water.

OffTheBackAdam

With PV, you're relying on the Government continuing to fleece us with feed-in tariffs. Without them they're completely uneconomical.

mrushton

There was an article on this in the Guardian some months back saying it was a good deal as the Govt. gave you money towards the system and you sold the surplus elec back to the Grid system. Sorry if I'm vague but there was money to be saved over the long term

http://www.guardian.co.uk/money/2009/ma ... NTCMP=SRCH

Article below is the one I was referring to. Hope they help

http://www.guardian.co.uk/money/2010/au ... NTCMP=SRCH

tarquin_foxglove

mrushton wrote:

There was an article on this in the Guardian some months back saying it was a good deal as the Govt. gave you money towards the system and you sold the surplus elec back to the Grid system.... there was money to be saved over the long term
http://www.guardian.co.uk/money/2010/au ... NTCMP=SRCH

Homesun, ISIS Solar and A Shade Greener are companies that will fit the panels to your house for free.

They obviously have quite stringent requirements over roof size, direction etc., and according to the Guardian you could be better off buying some panels yourselfbut if your home is suitable it could be a cheap way of reducing your bills in the short term.

PS A guy at work applied to the companies but apparently Durham is too far north for it to be economical for them. I seem to remember Johnny Ball (think of a number/man made climate change denier) said that PV wasn't economical above 50 deg of latitude which is all the UK except south Cornwall

Pep

Thanks all.

Let's not forget that the returns of the panels also depends on the cost of energy. My guess is that in future, both gas and electric, will go up in real term. So with energy prices going up the return period will shorten.

Warwickshire Whizzer

I work for a major construction company and on residential schemes we have to consider renewable technologies so that the emissions rate of the house meets building regulations. (I won't go into the fabric vs renewables argument here) but I can tell you we go for PV everytime. Granted our buying power is much greater than the consumer on the street, but it's more cost effective than solar thermal to us.

The feed in tarrifs make it a great option for future homeowners too, a 25 year guarenteed sum in your pocket is not to be sniffed at, and there are compaines offering free panels but you'll find they'll take advantage of the FITs.

It's likely the FITs will get knocked back in the ongoing spending cuts but I'd take advantage where you can. You'll find if they do continue, the people without the PV will subsidising the payments to those with.

On a commerical scheme I've got on my hands at the moment, the client has requesed we bolt a tonne of PV on so that theycan take advantage of the FITs, generates around £8m over the next 25 years...

BTW 1.5Kw peak of PV is 2 panels, can't see how 2KW is 8?

StanwaySteve62

HI Guys
Thought I'd jump in on this as I work for GE Energy.
We have just launched some PV invertors into the UK market.
A long shot but if any of you are in the business of buying such things drop me a pm
2, 3,4 & 5KW

maddog 2

a riding mate has just fitted a load of PVs to his house (he's an electrician).

I don't know the full details but the crux lies in the feed-in tariff, as said above.

The Gov has agreed the tariff for a long time, so if that stays true (and I couldn't comment on whether it will) then they are a good investment.

I'll see if I can get him to post something

JohnCleland

I work for a small housing association, and we have the benefit of attracting government grants for installing energy efficient elements to our stock.

We have installed PV, Solar Thermal, heat recovery systems, biomass boilers ect ect.

If it was a straight choice between PV and solar thermal, PV would come out on top, as mentioned 25 yrs FIT, reduction of electricity from the grid and also selling surplus electricity generated to the grid.

We carry out SAP assesments to our stock, before and after. PV raises the SAP by on average 9-10 points, solar thermal 1-1.5 points. The higher the number the better.

Thermal heats and / or pre warms the water, PV generates electricity, which can also be used to warm, pre heat water.

Electricity prices are only going to go up.

jugglingphil

I have Solar thermal on our small roof connected to a themal store (tank). Also have wood burning stove and gas boiler feeding into the tank. Bills are less and house is warmer, payback however is likely a be a long time!

I think PV is the better option at the moment if you have enough roof space with the right orientation. If you have a big enough roof you could do both, and more.