The Great 'Get Paid To Generate Energy' Hunt

Cardew

John_Pierpoint wrote: »

They were horrible "felt" shingles.
Even the wooden ones only last about 20 years - my mother's next door neighbour had them.
http://www.youtube.com/watch?v=IiRi0DIUcnY
An interlocking concrete tile should be good for 100 years, if made and fitted properly.

The householder was only getting 2.x kW when the fitters left - if I remember correctly.

Good point about the air conditioning.

Virginia still gets the odd hurricane/tropical storm so you don't want concrete tile missiles everywhere - or solar panels for that matter;)

Actually in the Southern hurricane belt - Florida/Georgia etc - solar panels fixed to a typical roof is a potential liability - you saw how easily they screwed the panel rails onto the roof. I have a place out there and having 'survived' some Cat 3 storms, the damage is amazing.

I noticed that fitter say 2kW so I assume that must have been late afternoon. As it was late June, I suspect that at noon they would be pumping out around 5kW.

Dave_Fowler

From what I understood from the video clip, each panel had its own inverter fitted beneath the panel. This would probably account for the higher cost.

If my understanding is correct, this throws up some interesting points:- The cost per inverter would be relatively low compared with the large single inverters generally fitted to UK systems - so the repair cost, if an inverter were to fail, would be less. However the probability of an inverter failing would be higher because there are more of them. The system would still work if one or more inverters failed so generation could continue albeit at a lower rate. The inverters could optimize the output for each panel to produce maximum output rather than optimizing the output of the entire array. This would help in the case of mismatched panels or shadowing on one or more panels in an array.

Here in the UK it is common to have two or more strings of panels connected to one single powerful inverter. Is there any advantage of adopting this multiple inverter system by separating the strings and having individual inverters for each string? Obviously the cost of two lower powered inverters is greater than the cost of a single one of double the power, but when it comes to repairs, the replacement cost of a lower power inverter would be less and FITs income would not cease due to a single inverter failure.

I'd be interested to hear of any thoughts along these lines.

John_Pierpoint

I wondered why the demonstration clip on "how to repair a shingle" showed each one held down by half a dozen nails.
As each panel has its own inverter presumably that solves the problem of a shadow passing over a panel or two, turning the whole thing off?
Do we rig these things in series (rather than in parallel) here in UK.
I was a bit worried about the inverter looking like an over sized house brick, being bolted under each panel. Not quite the place for WD40 and a blow lamp in 10 years time when trying to replace the rusty box? I suppose one would simply wait for good weather as only a small percentage of the installation would not be working.
As this is USA, what is the specification of the mains current (Here in the UK we have about 240 volts 50 cycles (?) and a company fuse of ?? amps as a typical installation). Perhaps the smaller inverters are mass produced in China for the American market and cost peanuts - after all I have one in my car, it cost about ten quid half a dozen years ago at Aldi. Nominal output 150 watts at 240 volts.

Cardew

John_Pierpoint wrote: »

Do we rig these things in series (rather than in parallel) here in UK.

As this is USA, what is the specification of the mains current (Here in the UK we have about 240 volts 50 cycles (?) and a company fuse of ?? amps as a typical installation). Perhaps the smaller inverters are mass produced in China for the American market and cost peanuts - after all I have one in my car, it cost about ten quid half a dozen years ago at Aldi. Nominal output 150 watts at 240 volts.

USA generally uses a nominal 120v 60hz - albeit it is usually referred to as 110v. Many newer properties are wired for both 120v and 230v, and 3 phase is not unknown in domestic properties with heavy heating/aircon loads.

The inverters must be in parallel.

With so many inverters, how do you tell if one is faulty? The electrician only had the wires from two banks leading into the house junction box, so the output of each unit cannot be individually monitored.

John_Pierpoint

Cardew wrote: »

With so many inverters, how do you tell if one is faulty? The electrician only had the wires from two banks leading into the house junction box, so the output of each unit cannot be individually monitored.

Choose a nice cloudless summer's day. When washing the panels, throw a black polythene sheet over each panel in turn as your better half indoors tries to see if there is a change in the total output?:T

Then have a row because she has lost count and muddled up the readings.:rotfl:

poohbear59

noncom wrote: »

Nonetheless, from a financial point of view, Cardew is right.

For example, Solar Hot Water systems can cost anything around £3k - £5k to install, and (without RHI-type subsidies) will give savings on water heating for a typical household of less than £100 per year.

Now, your barn may well be huge and therefore use more water than normal. It may also cost more (as you talk about oil and lpg) than usual to heat water. However, Solar Heating is highly unlikely to provide all the hot water required, and almost certainly not at the right times! So another heating system will be required as well.

Similar arguments may apply to your Air- or Ground-Source Heat Pump.

If you require a heating system to be fitted by this autumn, you will be taking a huge gamble installing renewables, financially at least. It may very well be the "right" thing to do environmentally, and my guess is that the Government will not abandon plans for the RHI, so it is still worth considering, but I would strongly advise holding off as long as possible until the facts are in. The loss of a few months' rent would be dwarfed by the amount you could potentially gain or lose according to what happens with the RHI.

Andy

Thanks, you have given us plenty to think about. We will hold off as long as possible. As this is a new business we need to get it right before we start up.

John_Pierpoint wrote: »

Beware of blandishments about heat pumps - the air source boys seem to use different standards from the ground source ones and both are over sold by salesmen not engineers.
I have never has a satisfactory explanation of what happens to the latent heat in the middle of winter when the air source machines turn into ice makers.

Ground source (or pond source:D) give a better efficiency when supplying heat via under floor heating (running at 35 degrees centigrade or less). It sounds like you may have left it a bit late for that option.Yes, we have all our floors laid with 600mm insulation then concrete.:

Both require supplementary heat in mid winter. (Log burner:cool: or socking big immersion heater :eek:)
Both put extra strain on the electricity supply, so it might be a good idea to beat you neighbour to the installation. We had to pay £3500 for electrical connection from a pole just 10 metres away. So it should be okay!!
Both are trickle technology and require a building with high insulation and preferably thermal mass.

It makes much more sense to spend an extra 300 GBP on insulation and checking air changes than 3,000 GBP on a bigger heat pump.

Although it is a barn conversion we have very high levels of insulation, much higher than building regs dictated and as the external walls are 3 feet thick in places we have high thermal mass. There will be a log burner in the main living area but is not connected into the main heating system as we have in our own house because we have no header tank (vaulted ceilings).

We are veering more towards ground source heat pumps ATM but need another source of heating the water for the radiators and would welcome any recommendations you have. One engineer who has been to look at our set up recommended an AMTEC and another immersion heaters.

We have all the pipework in for a wet system but no radiators or boiler as yet. When we first started this project oil or lpg seemed to be the way to go.

We are looking at this from a financial point of view first and then environmental secondly. One suggestion we have had from business advisor is to market it as 'environmentally friendly' in order to tap into another market for holiday letting.

poohbear59

Cardew wrote: »

If it is a barn conversion it will presumably have high ceilings?

I don't know how much you have read up on heat pumps(air or ground source) but the principle is that they work best(most efficiently) when they are only heating water to 35C or 40C(as opposed to up to 80C with oil/gas boilers) which is why underfloor heating is favoured. Either that or you want huge radiators.

It might even be an option to have warm air ducted to all rooms.

As indicated above, there is massive enthusiasm for 'all things heat pump' by some of the pioneers who have taken the plunge, but they have a tendency to gloss over the disadvantages.

That said, with RHI they are pretty certain to be a better option than oil or LPG.

The one thing I would insist on is that the MCS installer gives you some 'cast iron' guarantees e.g. with ambient temperature @ -5C, the system will be capable of heating living rooms to 21C and bedrooms to 18C. There is evidence that the specifications on some new installations in UK simply do not cope with a normal winter.

We have high/vaulted ceilings but no two story height ceilings other than the hall and live in area of the country likely to have -5 temperatures for a lot of the Winter.

At present we are presenting detailed plans of the house area to a couple of ground source heat pump manufacturers for quotes. I will make sure that we get some guarantees before we go ahead with anything. Today we were told it can take as long as two months to get quotes back so we won't be doing anything soon. Thank you

Cardew

poohbear59 wrote: »

We are veering more towards ground source heat pumps ATM but need another source of heating the water for the radiators and would welcome any recommendations you have.

Not understood!

The whole purpose of a GSHP is to heat water for the radiators and usually hot water for taps. Surely all of the GSHP systems have a back up Immersion heater for any time when the GSHP cannot cope in very cold conditions and to bring the Hot water up to 65C once a week or so to prevent bacteria forming.

mg2008

May have been asked before, but... What happens if/when the government cuts or reduces the FITS subsidy... Will the systems ever pay for themselves?

Mcfi5dhc

The government have committed to FIT for 25 years. Saying that, they could go back on their word (and obviously the government changed recently)

If they cancelled FIT, then you would probably get payback, but it would take much longer - in the region of 15 years+

But, if they cancelled FIT, they wouldn't hit their green energy targets, so I don't think it will happen. All the political parties seem to back FIT, and as the money doesn't actually come from government, there is no real reason to (FIT is paid by the big energy companies)

Thanks