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The Great 'Get Paid To Generate Energy' Hunt

edited 20 April 2010 at 9:21PM in Green & Ethical MoneySaving
651 replies 108.3K views
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  • alph250 wrote: »
    Well im a Building Services Engineer so I think I can put my 2 pence in!!

    As for installing them yourselfs?

    Please dont, The Solar thermal panels can reach extremely high temperatures and with high temperatures comes high pressures and with high pressure comes high risk which I wont go into, But by all means do the enabling work yourself if you feel competent but allways get a professional in to commission the system, set safety relief valves and high limit lockouts so the system will function in a correct manner, I've heard of a domestic system where the three port diverter valve was not set up right and allowed a calorifier to store hot water at a temperature of 90+ degrees as it wasnt set up right, now think if your child attempted to wash there hands?

    I absolutely agree on this!!! :T Hence my previous comment about following all building regulations and so on - the system has to be treated like an unvented system, which you need a particular qualification for so the system doesn't overheat and have bad results (so potentially an unvented engineer will have some skills for this). BUT as alph250 says, the commissioning is specialised and can be tricky for an experienced solar engineer, so it's always best to get someone who knows what they are doing.
    Saving money and energy seem to be the only things on my mind these days! :p
    ...installing solar energy!
  • edited 23 April 2010 at 12:57PM
    alph250alph250 Forumite
    18 posts
    edited 23 April 2010 at 12:57PM
    Well im a Building Services Engineer so I think I can put my 2 pence in!!

    As for installing Solar Thermal yourselfs?

    Please dont, The Solar thermal panels can reach extremely high temperatures and with high temperatures comes high pressures and with high pressure comes high risk which I wont go into, But by all means do the enabling work yourself if you feel competent but allways get a professional in to commission the system in a safe manner, set safety relief valves and high limit lockouts so the system will function in a correct manner, I've heard of a domestic system where the three port diverter valve was not set up right and allowed a calorifier to store hot water at a temperature of 90+ degrees as it wasnt set up right, now think if your child attempted to wash there hands?

    Solar Thermal payback periods?

    Just accept that you wont make the money back. I've presented options studies to various Facility Managers and explained all the benefits about how green they are, but when it comes down to the financials it doesnt work out, which is stupid really as you wouldnt apply a payback period to boiler! even though a solar thermal system would give some payback, but unless its over 20 years then never full payback. But do accept that you are using a green way of generating hot water and not burning natural gas (bad for the environment) and therefore doing your part for the environment this is what you should pay attention to!

    As for solar thermal efficiencys?

    The salesmens blurb about how there 85% efficient bears some truth. But only In mid July when the azimouth angle (angle of the sun in relation to the earth) is at its optimum angle. If you look at efficiencys for say October, this would be more like 55% and January about 15-20%. So the true way to look at it is seasonal efficiency, i.e. taking into account all months this figure is about 40-45% some months better or worse than others! And this figure will not change no matter what type of flat style solar panel you install, unless you adjust the angle monthly! These new flexible types i would imagine to be more efficient!

    As for Heat pumps?

    Excellent, You need to ask what the co-efficient of performance is for each type and choose the highest, commonly these can reach as high as 5.5 for a new commercial mitsubishi type (cant remember the model) But this would not be suitable for a domestic dwelling. a coefficient of performance or COP as its commonly reffered to is measured as energy in to energy out (ignore the 1st & 2nd laws of thermodynamics and if your confused then PM me!) So if you use 2Kwh to run the compressor on a ground/air source with a COP of 4 you would get 8Kwh out (less volumetric, isentropic efficiencys and system losses) So yes its like having a boiler thats 400% efficient! There brilliant, drawbacks are that because they run at about a 40^C feed and 20^C return Temperatures there not suitable for traditional radiator systems, however they are great for a new conservatory or new build home where you can install underfloor heating as a 40^C & 20^C return is ideal!!!

    As for Micro CHP?

    I must admit im very sceptical of these in the domestic market, In essence its an Heavy oil/gas Engine which runs a generator to supply electricty now these are about 30-40% efficient, however if you recover the heat from the engine coolant and exhaust and put it to use they now become around 85%. BUT you must make sure that the CHP is firstly sized for your electricity demand (no problems here any excess just feeds back into the grid!) and MOST IMPORTANTLY (i cant stress this bit enough) you must have a use for the thermal energy, or a thermal store which is sized to release this thermal energy over a period of time i.e run CHP for 6 hours per day, then use thermal store for the other 18 hours per day which is how i would imagine you would use it in a domestic situation. The only places I've ever installed these commercially is at swimming pools where theres a constant heat demand (the pool) and theres usually a constant electricty demand being the building. If you match the demands you maximise efficiencys, get it wrong and you've brought a white elephant which does more damage to the environment than good! its really that important!

    On a final note, Dont get hung up on investment pay backs and money making, you wouldnt buy a boiler and expect a pay back period? No so dont expect it on other types of equipment. To put simply If it saves energy it does save you money if you ignore initial capital expenditure But what you do do is your part for the environment so think of it like that!

    Oh and one other thing, If your looking at carbon reduction, think about where you buy it from, If it comes from China then the Carbon footprint would be huge when compared to an honest one built in the UK! (honest mean a non Cowboy!)


    Now rip what I said to pieces!!!!! hahaha:D
  • Solar PV is the way to go. For feed in tariffs it wins hands down. We have a 1.2KW system (7panels). This was installed in 2010 (after the eligibilty date for maximum tariff payments). We received a government grant for £2.5K and our local council matched this. Our saving, which includes what we save on our own bill and what we sell back to the grid, will be about £500. That makes our pay back time less than 5 years. I appreciate we were fortunate and received a substantial amount of grants , that are no longer available. The grants were there for one and all, you just had to look in the right places!

    The whole micro-generation is the way foward, do you trust the government to get it right? No new power stations are being built and no new ones confirmed. It will be nuclear or bust. The lights will go out. Even if you are not yet convinced by climate change camp there is one argument that no one disagrees with and that is peak oil production. The large majority now believe we have long passed peak oil production and this does not factor in the growth of economies in Asia, Africa and S. America. We have to get use to the fact (the sooner the better) that we are running out of oil and the other fossil fuels are not sustainable options. We have no gas, little accessible coal (though we have huge reserves!!) and North sea oil was sold a long time ago.

    We, as a society, need to think beyond the now. We also need to take into account that electricity prices will rise, some (independants) are saying the average household fuel bill will hit £2000 in 12 months. With less capacity here we will be forced to import more and prices will continue to rise. So any installation will have its payback time reduced. Is it all about the payback?
  • CardewCardew Forumite
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    alpha250,

    Nice post.

    A couple of comments:

    Solar Thermal is sold to the great British public as a sure fire money saver - and it aint! Countless thousands of people have been conned!

    "Dont get hung up on investment pay backs and money making, you wouldnt buy a boiler and expect a pay back period?"

    Whist I understand the point you are making, that analogy IMO doesn't stand up to scrutiny.

    We need electricity and a fuel for heating. They are freely available and if we have gas/oilLPG/solid fuel, we need a boiler.

    We cannot do without a boiler, we can do without Solar PV.

    Solar PV on your roof is simply a product that we sell(getting a huge subsidy) much like a farmer sells food and keeps some for his family!!. i.e. Solar PV will be fitted almost exclusively by people hoping to get a return on their invested capital.


    We invest £xthousand on Solar PV to produce a product(Electricity) which we sell and keep some for our family.
  • edited 21 April 2010 at 9:07PM
    CardewCardew Forumite
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    edited 21 April 2010 at 9:07PM
    Solar PV is the way to go. For feed in tariffs it wins hands down. We have a 1.2KW system (7panels). This was installed in 2010 (after the eligibilty date for maximum tariff payments). We received a government grant for £2.5K and our local council matched this. Our saving, which includes what we save on our own bill and what we sell back to the grid, will be about £500. That makes our pay back time less than 5 years. I appreciate we were fortunate and received a substantial amount of grants , that are no longer available. The grants were there for one and all, you just had to look in the right places!

    The whole micro-generation is the way foward, do you trust the government to get it right? No new power stations are being built and no new ones confirmed. It will be nuclear or bust. The lights will go out. Even if you are not yet convinced by climate change camp there is one argument that no one disagrees with and that is peak oil production. The large majority now believe we have long passed peak oil production and this does not factor in the growth of economies in Asia, Africa and S. America. We have to get use to the fact (the sooner the better) that we are running out of oil and the other fossil fuels are not sustainable options. We have no gas, little accessible coal (though we have huge reserves!!) and North sea oil was sold a long time ago.

    We, as a society, need to think beyond the now. We also need to take into account that electricity prices will rise, some (independants) are saying the average household fuel bill will hit £2000 in 12 months. With less capacity here we will be forced to import more and prices will continue to rise. So any installation will have its payback time reduced. Is it all about the payback?

    Welcome to the forum.

    On a money saving forum we really do need to divorce the 'Money Saving' aspects from the 'Green' credentials.

    Once someone knows the cost implications of fitting solar/wind etc then they can make up their mind about the wisdom of spending £thousands to 'help save the world'!! as well as getting a return on those £thousands.

    Obviously if everyone got a £5000 grant toward a £10000? PV system, the investment would be a whole new ball game. Or if you say payback in 5 years with a £500 annual income, I assume you only paid £2,500

    I certainly have not seen any forecast that the average household fuel bill will hit £2,000 in 12 months.

    The average bill is around £1,200 and Ofgem have forecast it will rise by 25% in real terms over the next 10 years. Indeed virtually all the Big 6 energy companies are offering fixed price deals at current prices. Or for a couple of percent extra on current prices, to as far in the future as 2015. So they don't envisage drastic rises!
  • Cardew wrote: »
    Do you appreciate that the high rate of FIT only applies when(retro) fitting to an existing house.

    For solar PV incorporated into a new build the rate is less.

    Thanks for that I wasn't actually aware it was different. I've had a hut around and came across this page: http://www.evoenergy.co.uk/DomesticPV/InvestingInSolarPV/FeedInTariffs.aspx

    Looks like it's 36.1p per kWh for new build which still isn't too bad.
  • :T Really useful - thanks. At last someone who appears to talk reality rather than hype! We would love to install - but given capital costs it would have to be DIY. The rich get richer - the poor get poorer - whatever the government 'colour'.
    Vagabond84 wrote: »
    Hi,

    Both the panels and the installer have to be MCS certified in order to get the tariffs. So even a qualified electrician won't be enough.

    However if you buy the panels yourself and they are accredited and then manage to find someone to install them who is accredited you may save a few quid that way.

    Do be careful when looking at accredited panels though and ensure they definitely are on the central register, which can be found here microgenerationcertification.org

    Sorry can't link to it as I'm new :)
  • neeyoneeyo Forumite
    2 posts
    Regarding these new 'feed in tariffs' and PV panels, has anyone wondered if it's worth heating your house with electricity if you have these panels iinstalled - and having no bills ! Would it work ?

    Say your gas boiler needed replacing, and maybe your system updating with new controlls etc. A new gas condensing boiler will cost around £2000 - £3000 to be replaced with all the work involved, power flushing etc. and what if say some of your controls are out of date/faulty.

    Is it worth putting the money YOU WOULD HAVE SPENT to have this done - say £3000 - and puting this towards PV cells (assuming you have a south facing roof of course, and a well insulated house ) And then heating your house and hotwater with the free electricity your generating ?

    OK you might not have much (or even any) SPARE electricity for the feed in tariff - but you'd have no bills ! And no expensive boiler that might go wrong or to have serviced. Just some fairly low cost electric panels for example and an electric immersion heater.(with a well insulated tank of course)
    Is this worth considering with the right house ?
    Do the figures stack up ?
    Anyone thought about this ?
  • edited 22 April 2010 at 12:36PM
    CardewCardew Forumite
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    edited 22 April 2010 at 12:36PM
    neeyo wrote: »
    Regarding these new 'feed in tariffs' and PV panels, has anyone wondered if it's worth heating your house with electricity if you have these panels iinstalled - and having no bills ! Would it work ?

    Say your gas boiler needed replacing, and maybe your system updating with new controlls etc. A new gas condensing boiler will cost around £2000 - £3000 to be replaced with all the work involved, power flushing etc. and what if say some of your controls are out of date/faulty.

    Is it worth putting the money YOU WOULD HAVE SPENT to have this done - say £3000 - and puting this towards PV cells (assuming you have a south facing roof of course, and a well insulated house ) And then heating your house and hotwater with the free electricity your generating ?

    OK you might not have much (or even any) SPARE electricity for the feed in tariff - but you'd have no bills ! And no expensive boiler that might go wrong or to have serviced. Just some fairly low cost electric panels for example and an electric immersion heater.(with a well insulated tank of course)
    Is this worth considering with the right house ?
    Do the figures stack up ?
    Anyone thought about this ?


    A couple of points.

    Firstly Feed-in tariffs! You get the FIT for all electricity you use regardless if it used in your house or exported and sold. So take a smallish system that might produce 1,000kWh a year. You get £415 in FITs. If you use half in your house you save another £50 and sell the rest for £15.

    Sadly your idea of using the electricity for heating is a non-starter.

    The amount of electricity they produce is tiny compared with the amount needed for even the smallest house; and they only produce electricity during daylight hours - nothing at night.

    Without getting too technical, a system costing £10,000 might produce about 1kW during the day - your kettle needs 3kW, so does an immersion heater and you might need 15kW or more to heat a house - and you need heat at night.
  • edited 22 April 2010 at 12:43PM
    noncom_2noncom_2 Forumite
    212 posts
    edited 22 April 2010 at 12:43PM
    Hi

    <Crossed post with Cardew - but have left it as written anyway>

    A few thoughts to that last suggestion.

    One: with the FIT, it doesn't actually matter whether or not you use ALL the energy you generate, you still get paid. The 41p rate is per unit GENERATED, and if you don't use it and export it to the Grid, then you only get an extra 3p per unit.

    Two: how are you going to heat the house using electricity? Storage heaters, or maybe electric underfloor heating? It's worth considering the capacity you'd need to heat a whole house this way (given that a typical immersion heater could be up to 3kW, and the maximum you will get out of the panels for the standard domestic FIT is 4kW and that's if you have a big roof).

    Three: you will have to heat the house and hot water during the daylight hours when the panels are generating. Bear in mind that in winter when you need most heat, you will be generating least electricity.

    Four: consider the cost of gas per kWh (maybe 5p?) and therefore in using a unit of Solar electricity to heat your home and water instead of exporting it you are only saving 2p per unit, assuming the efficiciency of you gas and electric heating methods are similar.

    Five: Every unit of electricity you use off the grid because you need to heat something when the panels can't sustain the demand will cost you perhaps 11p or more, so it would only take around 25% of your heating to require this to negate any savings completely.

    Six: Consider the £3k saved on the boiler as a discount on the PV panels, which is a significant saving, but probably only 20% of the cost of a 4kW system.

    Seven: Part of what makes the FIT scheme financially viable (arguably) is the amount you will save on electricity bills. By switching from cheaper gas to electricity you could be halving this component of the saving.

    I'm not a heating engineer, nor a microgeneration expert, but if anyone could come up with plausible figures to suggest this plan would work out financially in practice, I'd be astonished.
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