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A few sites I've stumbled across recently....

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Discussion > Can solar PV be profitable?

Sandy S

Even in Winter the sheds are net heat producers. Thousands of respiring chickens produce a lot of heat, which still has to be dissipated.

There is enough chicken manure produced in Northern to run a power station, though there are nimby problems.

Jul 18, 2014 at 8:50 PM | Unregistered CommenterEntropic man

Entropic man
Given the choice between a windfarm, a solar farm and a chicken manure power station of the same continuous rating being built in my backyard (figuratively) I think I'd plump for the latter.

I'll do a bit of research to confirm what you say about the heating issue.

Jul 18, 2014 at 9:54 PM | Unregistered CommenterSandyS

Jul 17, 2014 at 12:10 AM | Unregistered CommenterEntropic man

Your numbers looked a little odd so I decided to do a few calculations.

NIROC’s are valued at £43 each and in NI solar attracts 2 RO’s. Hence your friend will receive £86/MW and £7000 therefore represents 81.4 MWh (81400KWh), which is a heck of a lot. Given that at NI’s latitude 120 watts/m2 (average) insolation and at 10% efficient, solar panels will provide 105KWh/m2/annum (0.012 x 24 x 365). Your friend must therefore have 775m2 (81400/105) or about 500 1.6 m2 panels.

Three years ago I was involved in a roof type solar project, which is more or less in the time frame and hence costs as your friend, and against your £90k for 500 panels we had 50 panels for £46k. Payback was 11 years based on FiTs at 33p/KW subsidy and without the subsidy it was 45 years.

A big difference you must agree. Your comments would be most welcome, but please don’t come back with we were being ripped off. That was the price of solar panels at that time, before the Chinese tore the heart out of European manufactured products by lowering prices by 60%. Subsidy levels are now down to about 15p/KW under FiTs and are designed to give a payback of 10 years. Payback with subsidy reduced to half would be about 20 years. ref :

Jul 19, 2014 at 12:15 PM | Unregistered CommenterDavid Porter

David Porter

I'll be talking to the owner next week. I'll get back to you.

Jul 19, 2014 at 6:03 PM | Unregistered CommenterEntropic man

Entropic man
I did check the no heating required for chicken sheds thing. I got mixed results some said yes some said no, in Northern Ireland I would guess that heating would be required some winters?

Jul 22, 2014 at 10:31 AM | Unregistered CommenterSandyS

A comment by styleyd at pointed to this site which has some useful information.

Perhaps Raff might like to continue his discussion with the visitors to Paul's blog?

Jul 22, 2014 at 10:36 AM | Unregistered CommenterSandyS

A must read look at renewables (with germany and solar a significant part of the report) by the Swiss.

It repeats everything we've said.

Jul 22, 2014 at 6:19 PM | Unregistered CommenterTinyCO2

Sandy S

Three variables, the population of the shed, the temperature gradient between the shed and the outside, and the ammonia content of the inside air.

A typical 5lb laying hen produces about10 watts. For a standard 400ft by 40ft shed, 10,000 to 20,000 birds, that is 100 to 200kw.

An insulated shed will keep in enough heat to avoid active heating for most of the year, especially in a mild climate such as Northern Ireland. Temperature is controlled by varying ventilation rate. Layers do best between 20C and 24C. Young broilers, grown for meat, need higher temperatures at first.

A climate with sustained icy winters would need active heating in Winter, partly because of the high temperature gradient. The second reason is that you need to ventilate enough to stop ammonia accumulating in the interior atmosphere. If the minimum ventilation rate required to maintain air quality is removing more heat than the chickens generate, active heating will be needed to make up the deficit. Again, this is more likely in cold climates and cold weather.

In summary, if ventilation heat loss plus shed heat loss exceeds chicken metabolic heat production, you need active heating. If not, no heating is necessary.

This is probably why you are getting different answers from different sources. Differing climates and different types of chicken farming have different energy requirements. Even sheds in different parts of the UK might have very different heat budgets.

My direct experience is occasionally helping out a farmer in Northern Ireland with three 400ft sheds, producing fertilised eggs to be hatched and raised elsewhere as broilers. The fuel bill for the oil heaters is negligible; the electricity bill for lights and ventilation is awesome, which is why his solar PV installation is worthwhile.

Jul 22, 2014 at 9:29 PM | Unregistered CommenterEntropic man

David Porter, Sandy S

My numbers were a bit odd. :-{

I checked back with the farmer and got the following details.

His installation is approximately 1600 sq. ft, rated at 20kVA. ( The maximum output the local grid transformer could handle.) It cost £30,000.

He got 90kWhr on Tuesday, but Winter output is more like 15kWhr.
The installation is worth £5000 a year to him, giving a payback time of 6 years.

This is made up of of 17.5p/kWhr from the NIROC and 17.5p/kWhr from the saving on his mains consumption.

The sheds are active for 49 weeks a year. During cleaning he gets the NIROC paynent plus 5p/kWhr feedback tariff.

In his own opinion, what makes the installation worthwhile is the saving on his electricity bill, an appreciating asset. Running the system just to feed the grid would have given him a 12 year payback on a 25 year working life and would probably not have been worth the effort.

I also asked him about heating. The last time he had the heating switched on was during the very cold winter in 2010. He hasnt used them since. Their breeding stock is delivered at three weeks old and are self heating throughout their laying lives.

Jul 24, 2014 at 1:59 PM | Unregistered CommenterEntropic man

Entropic man

Thanks for your response.

Your numbers are no longer odd, except they are TODAY’S costs and subsidy rates and not those of a three year old installation. Also it would have been installed under a Feed in Tariff and not under NIROC (Renewable Obligations).

Jul 26, 2014 at 11:01 AM | Unregistered CommenterDavid Porter

Thanks Entropic man,
I guess the heating/cooling element of the costs depend on where you're located.

I should have asked earlier but did your friend mention anything about maintenance and failures? Don't worry if not as I'm only curious as there are a number of large barns round here with equally large PV panel arrays; we've had an awful lot of dust in the rain the last few months which, if my car is anything to go by, will affect PV output to some degree, I have to use the washers and wipers to clear the windscreen after most rain so I wonder what the local farmers do some cleaning or if they just leave it being too busy with other things. As I say if you don't know it's not a problem.

Jul 26, 2014 at 12:12 PM | Unregistered CommenterSandyS

David Porter

Those are the figures he gave me. The feed-in affected the size of the initial installation, but only happens in reality for 3 weeks a year when the sheds are empty.

Sandy S

The ventilation blows dust out of the vents. Depending on wind direction and rainfall they get hosed down about once a week. No failures to date.

Jul 27, 2014 at 6:34 PM | Unregistered CommenterEntropic man

£90,000 capital cost at 13,000/year over seven years. Without the subsidy repayment time would be15 years.

I wonder how reliable individual panels will be over their 25 year life?

That must effect whole life costs?

Most panels have a 10 year guarantee, if the manufacturer survives that long.....

Aug 9, 2014 at 4:08 PM | Unregistered CommenterSteve Richards