Solar PV

[theeggman]

Anybody out there with Solar PV?

During this hot spell our's are struggling to reach 3kw even though they are rated at 3.87kw and on a good day put out 4.3kw.

I am informed by the supplier that the work less well in high temps.

A bit odd as our panels were designed and built for the Australian market.

Is this standard or do we have a problem as it's very odd when we do get ideal solar weather the don't work at max. output.

Tim

 

[VEG]

Can you comment on the cost and returns as its something I have thought about but dread phoning these people to find out about.

 

[jd101k2000]

I would be interested in that too.

 

[MuswellMetro]

Anybody out there with Solar PV?

During this hot spell our's are struggling to reach 3kw even though they are rated at 3.87kw and on a good day put out 4.3kw.

I am informed by the supplier that the work less well in high temps.

A bit odd as our panels were designed and built for the Australian market.

Is this standard or do we have a problem as it's very odd when we do get ideal solar weather the don't work at max. output.

Tim

output of a silicon crystal Pv at 50c ( ie in direct sun on your roof at ambient temp of 30c) is about 75% of output at 25c (ie in direct sunlight at ambient temp 15c) As module temperature rises, all PV semiconductor technologies incur increasing losses in performance, primarily due to the drop in open-circuit voltage of the cell. The temperature coefficient to the rate of change of output as a function of temperature is typically a temperature coefficient of –0.45 to –0.5% per degree Celsius

even the more modern thin film cadmium Pv are only 85% at 50c

 

[enrico]

They work less well when hot! That is why they are mounted clear of the roof to try and allow air flow. If you could spray them with cold water they would be more efficient. Sunshine in cooler weather will produce better results. I am in my third year with them keeping careful records . My hot water panels however are another story. I have spring water heated to 70 degrees every day. Massive tank enough for three baths. Totally free! Woohoo!
E

 

[Beanwood]

Solar Thermal

My hot water panels however are another story. I have spring water heated to 70 degrees every day. Massive tank enough for three baths. Totally free! Woohoo!
E

This is Solar Thermal isn't it? That's what I'm interested in currently. My old oil boiler is about to expire, so looking to revamp the whole system. How loing have you had them, and do you think they pay for themselves?

 

[snoop]

I have had solar thermal evacuated tubes for 5 years now on my house . They are brilliant this year , but don't depend on them . Last summer I had to go out & turn on the oil to back up the cylinder once ever 3 days for a 1/2 an hour. You need an alternative source with them for the years we get the bad summers. I don't really think they cover themselves with payback here in Ireland but I must say it is great to come in & have a shower knowing there was no electricity or oil used to heat the water.

 

[itma]

Can you comment on the cost and returns as its something I have thought about but dread phoning these people to find out about.

Thing is that the deals on offer nowadays are nowhere near as generous as a few years ago.
But now the panels are cheaper.

So while other's experience can contribute data - on efficiency for example - they can't provide straight 'investment' info.

 

[Bee-Key-Pur]

I had 12 of then fitted on the cabin roof of my boat in the Caribbean, at great expense 15 years ago. They only ever give about half the rated output and only work half the time. The wind generators I later had fitted do a far better job even when the sun doesn't shine...

 

[roche]

I've fitted solar thermal - evacuated tubes - to two houses now. I wouldn't be without them. In terms of bang for your buck they are way ahead of solar PV. The prime source of hot water is solar, with a back boiler on the wood burning stove during winter. We do have electric immersion for backup, in the in-between periods.

 

[enrico]

I've fitted solar thermal - evacuated tubes - to two houses now. I wouldn't be without them. In terms of bang for your buck they are way ahead of solar PV. The prime source of hot water is solar, with a back boiler on the wood burning stove during winter. We do have electric immersion for backup, in the in-between periods.

I agree. I am on the welsh border so not loads of sun. However even in winter the tubes can up my large tank by several degrees. If the sun shines then that amount becomes even more and in the summer sun we never have to heat it. It helps to be on economy 7 type electricity. That way we all have showers in the morning. The sun works on the tank all day, we top up with electric if it needs it on cheap electric and the savings are good. It was already fitted when we moved in so we had no installation costs which helps. We had pc panels fitted too. They are not as good as we didn't have enough but we are on the top tariff so can't complain too much! The water is worth it but buy tubes and not flat panels as they are far more efficient!
If you want a copy of all my water heating graphs let me know!!
E

 

[theeggman]

Thanks for all of the replies.

It's good to hear that we aren't being taken for a ride.

We looked into PV after our accountant suggested it made sense to borrow the money if needed as the returns were better than the loan interest.

Our's were installed in Feb 2011 and we therefore get 45p+/kwh. + the export money. The panels were a lot more expensive than now but the FIT is a lot less now, but from what I gather they still make sense if you have a suitable roof a patch of ground in the garden to install them.

Even with current reduced output they are still exceeding the projected output that the financials were based on. Our energy co. has now started paying the FIT etc. within 2 days of our meter reading.

I think even with reduced FIT etc. they are still worth a look but get at least 3 quotes as there some cowboys out there.

Tim

 

[clv101]

For those thinking about solar thermal DECC have just released the Renewable Heat Incentive rates:

https://www.gov.uk/government/polic...supporting-pages/renewable-heat-incentive-rhi

An extremely generous 19.2 p/kWh!! If this is approved by government expect every south facing roof in the UK to have solar thermal within a decade.

 

[theeggman]

Just an update for those out there who are interested.

Yesterday, with the temp reduced to 20 deg C, the panels peaked at 4.367kw which is what we had acheived in the past.

Tim

 

[VEG]

Could you give some idea of the cost for outright purchase and how much you are getting back from the leccy you are making ?

 

[theeggman]

The cost for a 3.87kw system in 2011 £15,000. I'm assured they are cheaper now.
We get approx. £1,500 per year for the power generated. BUT we are on 2011 feed in tariff rates and they are a lot less now.
We use as much 'free' power as we can and our average annual bill for power bought in is £600, and that includes our water supply + water for sheep as we are on a borehole.
We are currently using 50% of the pv output ourselves.

I think that suppliers have to use standard data to give the projected output etc.

Hope this helps.

Tim

 

[VEG]

Many thanks for the info

 

[pargyle]

The cost for a 3.87kw system in 2011 £15,000. I'm assured they are cheaper now.
We get approx. £1,500 per year for the power generated. BUT we are on 2011 feed in tariff rates and they are a lot less now.
We use as much 'free' power as we can and our average annual bill for power bought in is £600, and that includes our water supply + water for sheep as we are on a borehole.
We are currently using 50% of the pv output ourselves.

I think that suppliers have to use standard data to give the projected output etc.

Hope this helps.

Tim

So .. your borehole water is pumped with electricity - is that on demand or does the pump run continuously ? Do you store the pumped water or is it piped straight in ... really interested in this as I've been looking at a property that has a borehole water supply. Not too far away from you actually ...

 

[einsteinagogo]

So .. your borehole water is pumped with electricity - is that on demand or does the pump run continuously ? Do you store the pumped water or is it piped straight in ... really interested in this as I've been looking at a property that has a borehole water supply. Not too far away from you actually ...

We are off a bore hole, and this is how we do it, by no means a master at this, we have two 20,000l tanks, which are pumped filled from the bore hole, they have a float to stop the pump running and filling them too much.

we then have a pump on demand system, which also pressurizes the water to mains pressure which feeds taps etc (the reason for the 40,000l of water storage is so we can run, showers, baths, housepipes, and my fish!), we found water pressure was too low without.

 

[theeggman]

We are off a bore hole, and this is how we do it, by no means a master at this, we have two 20,000l tanks, which are pumped filled from the bore hole, they have a float to stop the pump running and filling them too much.

we then have a pump on demand system, which also pressurizes the water to mains pressure which feeds taps etc (the reason for the 40,000l of water storage is so we can run, showers, baths, housepipes, and my fish!), we found water pressure was too low without.

Our system is similar to the above, we used to keep chickens and couldn't let the drinkers run dry,(2000 ltrs a day). Also down here we have a high iron + manganese content which has to be filtered out and when the filter backwashs there would be no water to the site for a couple of hours twice a week. Also when the borehole pump needs repairing etc we still have a water supply. Also, as above, the borehole pump struggles to achieve a suitable pressure when it's straight on line to the taps etc.

Tim