[Closed] To solar panel or not

I believe it's one of the most cost effective eco-technologies with the shortest payback. If you need re-work it could work out very well for you.

However you'd better wait for one of our resident eco engineers to come along 🙂

My parents had some an reckoned the payback was between 10 and 20 yrs. However its a nice feeling to have hot water without burning fuel in summer

How long ago tho Teej?

Good point - 20 odd years ago. I guess the installations are cheaper relative to energy costs now.

And probably better/more efficient too.

From a site selling the stuff:

Although payback is one way of looking at the cost it is perhaps more accurate to look at the return on your investment that solar thermal offers. Typically the financial savings of a good solar thermal system will be equivalent to a tax free return on investment of between 8% and 12%.

I read an article on The Observer about this not too long ago. The general gist was that not only are solar panels a poor way of generating power in the UK but the concessions that the govt. are giving to have it installed are outweighing the payback to the economy making it actual economically unviable too. The only people to benefit are those who can afford to install it and reap the benefits of increased property values.
I'll see if I can find an online link to the article.

^^^

Well in that case get it done as quickly as possible before the government takes away the concessions!

As well as using solar for hot water have a look at using them for electricity also. The new government feed-in-tarifs which came in to play in April pay you an index linked amount per kWH generated elecy (guaranteed for the next 25 yrs). And if you have any surplus then you sell that back to the grid for extra £££.

http://www.energysavingtrust.org.uk/Generate-your-own-energy/Sell-your-own-energy/Feed-in-Tariff-Clean-Energy-Cashback-scheme

Photo-voltaic cells are even more efficient than solar panels for heating water. South facing roof is required, or as near to it as possbile, otherwise it is a waste of time and money. allthepies beat me to it - check out the energy saving trust website.

In terms of energy efficient refurbishment measures to your house, for energy efficiency the best thing you can do is insulate and draft proof.

Then fit a new efficient A+ rated boiler, radiators and TVRs.

Once you have fitted a new boiler, the payback on Solar Thermal panels won't be very good, because you're not saving very much fuel to fuel the water (already very efficienct) - although you will still save some energy. Conversely if you were fitting a solar thermal panel to an existing, less efficient boiler, it would be a better payback.

At this point you'd be better off with a solar panel for electricity, i.e. Photo Voltaics (PV). This will cost about £6k-8k but is now a good investment due to the newly introduced Feed-in-tariff mentioned above by allthepies. You can get something like 38p/kWhr for all electricity that you generate. Would getting a bank loan to do it, probably. And you will save significant amounts of carbon intensive electricity in the process.

For some more info see http://www.tzero.org.uk/About.aspx

Lots of insulation, draft proofing, better (thicker) double glazing all in hand.

I take wonny J's point about the payback period being much longer once a new efficient boiler is installed. Not to bothered about the payback period all good things are worth waiting for.

Will have to do some more research into costs and possible PV cells. I had discounted PV as I thought it wasn't worth the effort to generate such a small amount of energy.

If fitting a new condensing boiler then pre-heating the water may not be great as the boiler wont condense.

Not sure if the payback periods are finiancially worth it even considering feed-in tarrifs etc. Its more a question of whether you want to do your bit or not.

While not commenting on the Solar side of your question, I will say that I have had a vented system with an aged boiler system ripped out and replaced with an unvented cold water pressure fed, hot water system. This is absolutely fantastic and would recommend this over a combi boiler for all but the smallest of properties.

Except that the OP is asking how to spend money to make his house eco, he's asking that GIVEN that he is already replacing central heating, is it worth fitting solar?

Solar PV cells are in no way related to the project he is undertaking.

Solar panels will supply some of your hot water demands from taps but none of that needed by the central heating so it won't mean you no longer need to heat hot water. Not got any figures to hand but the payback seems to be in decades not years. Not looked at a DIY system but that might be better.

PV panels are OK due to the Feed in Tarrif but payback about 10 - 15 years depending on how you view certain things changing over time (eg electricity prices, interest rates). If you work out the figure don't forget to factor in how your capital would grow if not spent on PV panels. ie you have £10k. Invest over 10 years and it will grow at say 4%. Buy PV panels and you have zero in the bank but each year generate income of say £1k.

This will cost about £6k-8k

Also just had a combi fitted and while it's OK (1 bath, three sinks in the house) I don't think I'd go for another one. Second getting the insulation, TRV and learning how to make best use of the system.

but none of that needed by the central heating

[url= http://www.greensystemsuk.com/solar_questions_t.php ]No? This company sell solar assisted central heating.[/url]

The same site quotes figures suggesting that you'd get 24% of your heating or hot water in January for free, and 90% in mid summer.

Cost of installing Solar Hot Water is about £4-5k. Make sure the system boiler cylinder you buy is compatible for solar hot water. Renewable Heat Incentive (RHI) if it happens, might provide a FIT style payback, but not until 2011 at the earliest.

I would still say the pv/FIT route is much better than the hot water panels, as you'll be able to make money on your installation (after a few years payback) rather than just slowly pay off the initial investment. Much quicker payback.

With solar thermal hot water, you will only save gas, on an already efficient system.

With solar PV you will save on electricity, which in carbon dioxide terms has approximately a 2.7 times greater carbon intensity than gas. Good for displacing the impact of any TVs, kettles or computers you might have.

Why does everyone talk about payback times for solar energy? they don't talk about payback times for a boiler or insulation, or do they?

To quote from that site....

Can solar thermal system heat my radiators?
Yes it can give you a % of heat to radiators but it is more suitable when installed with underfloor heating.....it is possible to heat you home by solar but it is unlikely that you would install the system because of
cost.

OK, so you could install underfloor heating to go with it but even then it's not cost efficient.

For pv a rule of thumb is £4k/kW installed. Although this a highly variable depending on what company quotes.

In terms of size, roughly 4m2/kW

People regularly talk about payback times for retrofit insulation.

And also for replacement boilers, but not for new ones.

But this isn't retrofit, the OP needs to replace the lot anyway.

I'd say call a company and get a quote, not listen to these weirdos 🙂

If you're not on mains gas, you could also consider as air source heat pump boiler. Even if you are on mains gas, going down this route could save you money by getting rid of your gas requirements & saving on the standing charges.

Would second the need to thermally improve & seal the house, & reducing the need for heating which conversely increases the percentage costs attributed to DHW production & back too solar panels.

Personally don't like combi's preferring un vented systems.

Actually I'd say PV costs more like £5-8/kW installed.

Molgrips, why is this not a retrofit project? If the house is already built then it is a retrofit or refurbishment.

"Even if you are on mains gas, going down this route could save you money by getting rid of your gas requirements & saving on the standing charges."

BS!

http://www.bsdlive.co.uk/story.asp?storycode=3142370

If it was an offgas property in Devon then I'd support an ASHP. But as they're on the gas network I'm not so sure.

Well ok but it needs doing anyway, so the payback times should be calculated on the cost of solar OVER the cost of a normal system... which should change it radically no? And PV is also not part of the equation.

I think the payback for Solar Hot Water fitted to an A+ rated boiler is pretty poor, like >20yrs.

on page 173.

For more opinion I would recommend [b][url= http://www.newbuilder.co.uk/ ]the forum on this site.[/url][/b]

You will get much more impartial advice on that forum than you will get from speaking to any installers or sales people from a solar (or ASHP) company.

bigsurfer, have a look at [url= http://www.navitron.org.uk/product.php?proID=86 ]these[/url] DIY systems from Navitron.

Navitron have an extremely good [url= http://www.navitron.org.uk/forum/index.php/board,6.0.html ]forum[/url] with lots of knowledgeable members.

I am in a similar situation to yourself and will be installing a solar heating system and new boiler.

PV systems are horribly expensive and very inefficient (something like 20%). Thermal systems are cheaper and can be about 90% efficient. They offer you the best bang per buck.

PV is great for reducing energy consumption but I didn't think that's what was being discussed here.

Go and speak to the Newbuilder forum people and the Navitron forum people.

Thanks for the Navitron link.

Lots more reading tonight then.

second looking at air source heating. if you use air source do not get solar as well as they are both solar technologies.

Lots of very interesting and useful information coming up here. Can I just suggest to the OP that if you do go down the unvented stored HW route that you have a circulated system installed. You will prob save more in water bills than in fuel bills. Also wasting water is really bad for the enviroment.

if you do go into the micro generation route you can earn money from it on the new feed in tariff scheme. I work for ecotricity who support it.

http://www.ecotricity.co.uk/for-your-home/microtricity

jakeclyro is right and hoodoo is wrong about paybacks. FITs turns the old financial model (hoodoo) on its head.

molgrips, I think the OP is interested in saving energy, that's why I suggested it. OP said, "I like to think I am as Enviromental as possible", which I took to mean saving energy and reducing carbon emissions.

Bear, air source heat pumps (ASHP) and solar systems actually make a good match. (it's not like the ASHP gets in the way of the panel, one is generally at ground level, the other is usually on the roof). With solar hot water, you can reduce the heat demand from the building and therefore the work the heat pump has to do. With PV you can provide some of the energy to run the pump. Neither of these however, addresses the fundamental problem with ASHP which is poor preformance in winter, when the external evaporator coils may freeze up. All a bit irrelevant as ASHP
is not a good choice for any property on mains gas.

matt_outandabout, dropoff and jakeclyro are talking sense.

Wonny - yes but an air source works most efficiently when the ambient temperature is higher (when the sun comes out and mainly in the summer) which bizarrely is also when solar panels work best (although there is a school of thought that says solar panels are not as good when they get too hot). So you are buying 2 technologies that work best in the same conditions, also in the summer you don't need your ASHP for heating but it will run hot water perfectly.

If you buy 2 systems payback will be far longer, if ever. If you are buying one and it works in your building buy ASHP as it offers far more than just hot water. Also some interesting new figures being talked about for grants for homeowners for them, not sure if they will get the go ahead but if they do then it becomes a no brainer.

wonny j, I'm intrigued. I've just re-read my thread and can't find any specific mention of payback although I suppose you could argue that it is implied where I stated that PhotoVoltaic is more expensive and less efficient solar thermal.

I'm also feeling a bit dim this morning as I have no idea what "FIT's" is

feed-in-tarrif.

Bear, basically my problem my problem with ASHPs is the lack of any independently published data on the performance. There are lots of manufacturers claims, like coefficient of performance of >4.5 However, in practice because the poor performance in winter this would seem to drop significantly, and if it gets near 3 then you might as well stick with an efficient gas boiler.

Some of my colleagues have looked into this and it would seem that attempts to publish proper performance data have actually been pulled by manufacturers.

Anyway, the people I've spoken to who have had extremely high bills for this winter, aren't too happy with their ASHPs performance.

I suppose the renewable heat incentive might change this, but who knows at this point?

What about a GSHP then? much better heat reservoir for the winter?

Some people here seems a bit confused abvout the difference between PV and solar thermal.

I think the jury is still out on PV, but...

When you consider solar thermal it is not just about the current payback, but also about insulating (no pun intended) yourself from future price shocks. Gas may not always be as cheap (or even available at all) as it is now.

Another option you could consider is a thermal store - I've got one from [url= http://www.heatweb.com/ ]these people[/url] although other makes are available.

They are expensive, but the advantage is that they will accept inputs from just about any heat source you want. Currently mine is powered by immersion heaters on Economy 7 (I'm intend to add solar thermal but am in a conservation area so there are planning issues) - but it also has tappings to add a boiler or a feed from my wooburner if I want. Similarly it currently only supplies hot water but could also act as the heat source for central heating.

One other advantage of this system is that is is open vented, which means no annual maintenance (unlike an unvented system) and no risk of explosion when you start adding different heat sources.

My main advice would be do plenty of research before you buy - there are lots of options and they are all expensive, so make sure you are very comfortable with your decision before you spend money.

[url= http://www2.dupont.com/Photovoltaics/en_US/ ]photovoltaic[/url]
Go on keep me in a job 😆

ASHP's aren't the most efficient things despite manufacturers claims, CoP's closer to 2 seem more the norm. Didn't they used to be called air assisted electric heaters? There should be some independent heat pump data coming out in a few months or so. Insulation and air tightness, as unsexy as they are, are the really important things to get right.

Going back to the OP, I reckon (evacuated tube) solar thermal to heat water is a good idea particularly for green rather than financial motives. Although the renewable heat incentive due next year covers it, at least in the consultation I think, so there could be an additional income from that depending how the scheme is implemented. Vented or unvented? - if the Navitron and builders forum don't help then find some local installers and have a chat.

Forgot an important point about the thermal store. It is vented BUT you still get your hot water at mains pressure.

Dont be fooled into thinking that an ASHP will be great for heating your house. You need to heat your house when its cold outside, exactly the time when ASHP will be at their least (roughly 1 to 1) efficient. You might as well have night storage heaters and only pay e7 prices.

GSHP are a much better idea, BUT only if you can install underfloor heating. If you having full on refurb, this may be an option.

Solar hot water, will reduce the domestic hot water cost to some degree. Generally works out to be about 20% reduction.

Solar electric (PV) not too sure on this.

Interestingly I just went to a talk on this the other night. The expert, was an archetect designing low energy buildings. His view was that any renewable energy (on a single house) was just eco-bling. His advice was spend the money on more draft proofing, better insulation, triple glazing, highest efficiency boilers/appliances etc. All of which can be very very expensive to do really well. GSHP was a good choice if the house was suitable.

Having said all that, I know how emotive these issues can be, and peoples very different attitudes to things!

His advice was spend the money on more draft proofing, better insulation, triple glazing, highest efficiency boilers/appliances etc

And what about when you've done all that?

When you've done that really really well there's no cost imperative to do anything else. Apart from hook up to a district heating scheme.

Yep, all part of the energy hierarchy. Reduce demand --> improve efficiency --> generate from renewables, in that order.

And what about when you've done all that?

Once you've done all that, there is very little else to do. Job done!

I don't mean to sound glib with that comment, just that once you have done all that, you'll be using very little energy. Any savings will therefore be minimal. Going the extra mile with solar hot water would save some energy during the summer months, if your not interested in payback then this would be the next/last step...

...Really though I wouldn't bother, if you have money left over (lucky thing) then start looking at greening other areas of your lifestyle. The house is done. Now work on transport, food etc. That will save much more energy than domestic hot water heating.

We are renovation a house at the mo and doing a similar thing. We have a mixture uf UFH & rads for heating. We will be fitting a condensing system boiler which then feeds into a thermal store. This is for 2 reasons, condensing boilers generally achieve their efficiency when running at full tilt, not when you are just using enough water to wash your hands. The thermal store has coils for heating & dwh. So the boiler runs flat out every so often to keep the store warm. Also the store has other sets of coils that will allow us to fit solar and or ASHP at a later date.

FYI the store is about £2k from these guys:-

http://www.chelmerheating.co.uk/thermalstores.html

We have also gutted the house and added about £5K work of insulation to the walls floor & roof.

Good work mos. Sounds like you have the right ideas, and the right approach ie doing it all at once during a refurb.

I've never heard of the heat store idea before, but it sounds like a potentially viable idea. Would be interested to know how it works out in practice.

Fair point - our new build house uses very little heating energy anyway, and there are still places I reckon I could insulate it further. So if I were to invest in anything it'd be PV I reckon.

Although surely - the more your total heating bill goes down, the greater percentage of your usage could be achieved with solar? I mean if solar hot water cuts 50% of your gas usage, then you save 25% of your gas usage via insulation, you'd still get the same amount of energy from solar - so your percentage from solar would go up to 66% right?

Yes but it would be a greater percentage of a much smaller total.

Hang on tho. If solar gets you X watts of power, and your house needs Y watts, then you'll spend Y-X on the equivalent mains gas. If you insulate loads to the point where Y = X, then you need no gas at all.

I don't understand where people are getting the idea from that you can get enough solar energy (of any form) to contribute to heating a house.

If my understanding is correct (might well not be) there just isn't the energy to do it during the winter months, when your heating is on.

Far enough during the summer there is generally plenty to heat domestic water (ie baths/showers/taps), but this will be a small fraction of you total yearly energy use.

All the stuff I've seen says that there IS enough solar energy to make a difference to your bills. And if your bills are super low to begin with, it'll make more of a difference in percentage terms.

What the others on here are saying is that the initial cost of the system might not be worth it against the savings.

heat store = thermal store

I gave a link to DPS who are another manufacturer earlier.

I don't understand where people are getting the idea from that you can get enough solar energy (of any form) to contribute to heating a house.

Well you can, easily, but it does mean building a [url= http://en.wikipedia.org/wiki/Earthship ]completely different kind of house.[/url]

or a [url= http://www.greenspec.co.uk/html/opinion/passivhaus.html ]passivhaus[/url]

(scroll down a bit)

[url= http://www.bere-blog.co.uk/ ]Wow, ecohouses that look good and also perform well.[/url]