Solar Power-is it worth it?

Cardew

Foodjunkie wrote: »

I work for a consultancy who designs M&E for new builds. Solar heating for hot water is a great idea and is catching on in this Country. (Check out the houses in and around the Med). The main drawback in this Country is that in the winter period, The water is just not hot enough, its tepid and requires a "boost" from the boiler or immersion heater.
Most systems come with a 10 year warranty, but the main hurdle is the cost of installation, you are talking up to 10K for an average house.
Interest from local Authoritys is high, as they are starting to install the solar water heating panels on school roofs and some prisons.

Perhaps over time as manufacturing costs reduce, and installation grants are made available form the government, it might catch on big time in the UK.
Untill then, just insulate the house the best you can, using what ever grants you can get your hands on.

Schools and other public buildings are fitting solar for environmental reasons, and thus demonstrate their 'green' credentials, rather than any attempt at money saving; and that is a perfectly valid reason.

I don't think many firms, in an industry that riddled with 'rip off' merchants, attempt to charge £10k for the average house for solar hot water - £3k-£4k seems to be a ball park figure. £10k for solar electricity perhaps.

Also I have not seen any domestic solar water system with a 10 year warranty, the solar panels perhaps, but not the pumps, electronics etc. 2 years seems to be the norm.

radcon

Foodjunkie makes a good point.

At the minute, with High Purchase and Installation costs Solar isn't viable for the masses. ROI just isn't good enough. I work in the industry and I haven't (or would) put Solar on my roof.

I speak to a lot of people (some for the right and some for the wrong reasons) who want solar (or other form of renewable energy) in their system. It's amazing the no. of people that don't have a condensing boiler - or who have one that doesn't condense (a seperate argument altogether).

I must make this clear that this is MY opinion, but the order in which things should be done are:

1) Insulation, insulation, insulation/Double glazing
2) Condensing Boiler / Proper Heating Controls, including zoning, not just TRV's
3) Weather Compensation
4)Air Source Heat Pumps
5) Ground Source Heat Pumps
6) Solar (if at all - sorry got to be honest)

There are exceptions to this as there always is. An example of which would be a new build built on piles - a ground source heat pump would be more viable than air source.

Or living in California - Solar might be an investment.

Anyway - like I said, it's my opinion only.

moo2moo

To clear up any confusion I have created.....

The heat dump is drained over winter to prevent the pipes freezing. This renders it non-operational.

During winter (ie Nov, Dec, Jan, Feb) the temperature demand from the underfloor is reduced to a background heat only in order to keep the hot water supply to the bathroom warm enough for hand washing (but insufficient for any period of time eg. a shower). This is not warm enough to heat the room independently. The cut off temperature for supplying the underfloor heating is 45 degrees celcius at the centre of the thermal store. The underfloor heating draws heat from the thermal store until this is reached. The background room temperature of the area with underfloor heating is generally 10-12 celcius Nov-Feb. Currently its running at 20 celcius (6:30am).

By after winter I mean spring. This year it was March during which the thermal store reached excessive temperatures.

The Solar panel is directly above the thermal store (2m pipe run). The thermal store is adjacent to the bathroom (0.5m pipe run) meaning we have negligable heat loss via pipe runs. The thermal store currently has no operational inputs other than a 30 tube solar panel measuring approx 3.5m x 2m. The underfloor heating is installed in a thicker than average floor slab with additional insulation beneath and around the slab. This means it can take up to 2 weeks to heat up but maintains this heat well.

The use of 3 stoves has reduced my log consumption. Prior to that I was heating the house via 2 open fires. Converting these to stoves has increased the length of time the house stays warm. I'm now considering a Raeburn or Aga.

Moonrakerz - what facts and figures do you want?

I didn't install solar as a short term fix. I've been here 10 years, I have no plans to move. Ever. I have an intermittent electricity supply in the windiest weather. No mains electricity :- no conventional boiler or cooking facilities or hot water. I run a back up diesel generator which powers the solar system and a fridge/freezer. I have no shadows over the panels at any time of day. Solar works for me.

Whether or not solar is cost effective is entirely dependant upon the period of time you are looking to gain your return. If you are hoping for a quick return then no solar is not cost effective. If on the other hand you are looking at this over a longer period of time (8 years or more) then yes it is. Of course this all depends how much you spend on the system in the first place and how much the gas and electricity bills creep up. If the cost of LPG continues to double every 2 years then more and more people will be forced to consider alternatives.

shandypants5

It seems to me that the huge savings people are seeing are coming from NOT using the terrible water heating systems they used to use..

If you have a stupid system that cost £500 a tankfull to heat water,then just not using it will save you £500 a tankfull.

That doesnt mean your new solar unit is providing £500 worth of hot water,
it just means that you were paying too much to heat your water the old way.

There are lots of ways to fix bad heating systems, and maybe solar is one of them.
I think you need to look at the cost of installing solar against the cost of installing a more conventional efficient system.

wpp34

I am totally confused by the arguments in this thread. Most of the sites giving info on solar water heating quote 'free' hot water for summer and about 50% free in winter. A rough calculation based on my spend of £75 per month on gas for heating and water would 'save' me about £35 -40 a month in the summer and about £15 -20 a month in winter, say £340 a year tops. System for my house would cost about £4500 (expensive because need scaffolding for work on roof!)so pay back over 13 years!! This is not taking into accout the cost of electricity to run the pumps. However if I deposited the money at the best savings rate available I would only get about £230 per year in interest after tax so that makes it seem a good prospect. And as I reckon to be on a pension soon then anything that reduces outgoings is worth it to me. Any comments welcome.

Cardew

wpp34 wrote: »

I am totally confused by the arguments in this thread. Most of the sites giving info on solar water heating quote 'free' hot water for summer and about 50% free in winter. A rough calculation based on my spend of £75 per month on gas for heating and water would 'save' me about £35 -40 a month in the summer and about £15 -20 a month in winter, say £340 a year tops. System for my house would cost about £4500 (expensive because need scaffolding for work on roof!)so pay back over 13 years!! This is not taking into accout the cost of electricity to run the pumps. However if I deposited the money at the best savings rate available I would only get about £230 per year in interest after tax so that makes it seem a good prospect. And as I reckon to be on a pension soon then anything that reduces outgoings is worth it to me. Any comments welcome.

Most of the advertising sites talk complete rubbish. Their usual ploy is to say 'Up to' £xxx savings. Well if it was 'up to' £100 savings, that covers a saving from £1 upwards.

Have you not seen the TV Watchdog type programmes? Ring trading Standards and ask for their views - it is their biggest source of complaints. They have loads of legal action taken and pending against firms for misrepresentation.

Firstly solar water only provides Domestic Hot Water(DHW) i.e. hot water from the taps. It does not provide any heating for the house.*

Now the average house only uses 3,000kWh per year for DHW. So if you have gas, that will cost you between £60 and £90 a year.

You will be very lucky if you save 50% of that - so your savings are likely to be £30 to £45 a year.

Even if you use double the UK average for hot water, let us say 6,000kWh per year, you won't get a system(not for £4500) that will provide 50% of usable DHW.(3,000kWh) but even if you did, you are looking at savings of £60 to £90 a year. That is before you take into account all the other expenses.

So your figure of £340 savings is simply a joke!

If you look at some non advertising sites - like the Government commissioned tests of 8 solar systems under controlled conditions, they produced on average 1,000kWh pa- which will save you between £20 and £30.

Even some of the more responsible firms openly state their systems will produce between 800kWh in North Scotland to 1,200kWh in SW England.
So savings again in the £20-£30 region.

Just ask the firm that have given you a quote of £4500 what output the system will provide in kWh and they won't give you one!

I have no axe to grind, but if you get annual savings in the region of £50 a year you will have done very well.

* there are specialist systems(costing a lot of money) that provide HW to a thermal store for heating, but they are rare.

wpp34

Cardew, the joke about the prices is exactly what I am still confused about! It's to do with the validity of the claims that I can get 'free' hot water in the summer and about half of my hot water 'free' in the winter. I am only considering the DWH and according to last summers (May to July)gas bill I averaged 1500 kwh per month on gas, so if I save most of this then I am close to my figures. I'm not really interested in how much power the systems produce so much as the amount of hot water they produce and the gas I don't have to buy. If they don't produce anywhere near the amount of hot water claimed then fair enough

Cardew

wpp34 wrote: »

Cardew, the joke about the prices is exactly what I am still confused about! It's to do with the validity of the claims that I can get 'free' hot water in the summer and about half of my hot water 'free' in the winter. I am only considering the DWH and according to last summers (May to July)gas bill I averaged 1500 kwh per month on gas, so if I save most of this then I am close to my figures. I'm not really interested in how much power the systems produce so much as the amount of hot water they produce and the gas I don't have to buy. If they don't produce anywhere near the amount of hot water claimed then fair enough

Sorry I don't understand what you mean by 'power'.

Energy produced by Gas, Electricity, Oil or Solar can be measured in kWh. Thus the normal measure of energy for producing DHW is given in kWh.(because that is how we pay for energy) So if your solar panels produce 1,000kWh of energy a year, that saves you buying 1,000kWh of gas at a cost of £20 to £30.*

It depends how big your solar panel array is for the amount of energy kWh it will produce; and then of course you have to consider how you use that hot water.

What is the use having a huge display that will produce huge amounts of DHW in the summer that you can't use.

Now your usage. As I stated above, the average UK property uses approx 3,000kWh to heat their DHW for a year. If you use 1,500kWh a month in the summer, you are using over 6 times the UK average;(18,000kWh) which seems unlikely. In fact you will use more gas in the winter as the input temperature of mains water is lower.

Depending on the size of your HW tank, and the temperature of the HW you want, it takes between, say, 3kWh and 6kWh to heat a full tank of DHW.

You say you are using, in summer, 50kWh a day to heat DHW that is many full tankfulls a day???

Anyway, all I can suggest is that you do a little research on the internet to satisfy yourself of your savings. I have done my best to give you an honest appraisal; if you think I am incorrect - so be it!

*
In discussing costs I have deliberately not taken the efficiency of a gas boiler into account as this can vary from, say, 60% to 95%

dekh

wpp34 wrote: »

I am totally confused by the arguments in this thread. Most of the sites giving info on solar water heating quote 'free' hot water for summer and about 50% free in winter. A rough calculation based on my spend of £75 per month on gas for heating and water would 'save' me about £35 -40 a month in the summer and about £15 -20 a month in winter, say £340 a year tops. System for my house would cost about £4500 (expensive because need scaffolding for work on roof!)so pay back over 13 years!! This is not taking into accout the cost of electricity to run the pumps. However if I deposited the money at the best savings rate available I would only get about £230 per year in interest after tax so that makes it seem a good prospect. And as I reckon to be on a pension soon then anything that reduces outgoings is worth it to me. Any comments welcome.

I do seem to have a bit of a downer on green schemes at the mo, but are you sure you are interpreting your figures correctly?

For instance if you are going to save £340 pa you will get break even on your investment in just over 13 years.

Using my simplistic maths

In 13 years you will have earned ( 13 x £230 ) £2990 which as you say isn't as good as the amount you will have saved ... but ... you will actually have (4500 + 2990) £7490 in the bank.

OK take away the extra cost of heating £4500 so we are back to £2990

But that is £2990 better off.

I have here ignored:
Compound interest which will put significantly more in your account
The declining amount of capital used to pay the heating charges
Maintenance charges. See your warranty here you could get stung badly by anything not covered - yyou mentioned extra cost for scaffolding, if they need to reerect for maintenance will you have to pay?
Rising heating costs.

Would you not be better off doing the less glamourous, significantly cheaper and more environmentally friendly insulation things? I know that doesn't reduce hot water requirements but it does have a big and more permanent effect on heating bills.

Just my 2 penneth.

Cardew

dekh wrote: »

I do seem to have a bit of a downer on green schemes at the mo, but are you sure you are interpreting your figures correctly?

For instance if you are going to save £340 pa you will get break even on your investment in just over 13 years.

Using my simplistic maths

In 13 years you will have earned ( 13 x £230 ) £2990 which as you say isn't as good as the amount you will have saved ... but ... you will actually have (4500 + 2990) £7490 in the bank.

OK take away the extra cost of heating £4500 so we are back to £2990

But that is £2990 better off.

I have here ignored:
Compound interest which will put significantly more in your account
The declining amount of capital used to pay the heating charges
Maintenance charges. See your warranty here you could get stung badly by anything not covered - yyou mentioned extra cost for scaffolding, if they need to reerect for maintenance will you have to pay?
Rising heating costs.

Would you not be better off doing the less glamourous, significantly cheaper and more environmentally friendly insulation things? I know that doesn't reduce hot water requirements but it does have a big and more permanent effect on heating bills.

Just my 2 penneth.

But please let us not even begin to base any economic discussion on the quite unbelievable figure of £340 p.a. savings.