Interesting slideshow on solar panels

KAGY

Just found this via random googling

http://www.ilsu.ie/documents/SemRE/SHSolar.pdf

it's a nice introduction to solar panels, technology and costs.

PeteHeat

Hi,

A shame, what could have been a valuable slide show loses all merit at the suggestion that the water temp required at the tap is 60c :eek:

People who publish such dangerous information should be made hold their hands under a tap with the water running at 60c, another "Expert" who has yet to discover the merit of a mixing valve.

Obviously I am biased toward solar, that said why have shower manufacturers been fitting the safety valves to max 40c ?

The figures appear to off based on the information provided by Dundalk I.T.
(they are better at maths than me) for example the saving on oil by their calculations is at minimum 500 litres per year.

I could be wrong but I understood all solar panels / tubes sold in Ireland had to qualify for Solar Keymark which I understand requires a minimum output of 550 KWH P.A..

It appears the systems tested were of poor quality or the figures need to be reviewed.

Doctor_L

I work with Seamus Hoyne who produced those slides. Seamus is also head of the Tipperary Energy Agency and has been working in this area for several years.

Seamus always approaches these issues from a pragmatic and practical view.

PeteHeat

Hi Doctor_L,

I have no doubt the author is a decent person, I think if you read my post I stated it could have been a valuable slide show.

The devil is in the detail such as the temperature of 60c required at the tap also the figures for the output of the panels are in contradiction to what is the minimum test certified products sold in this country.

Of course if we had a genuine standard stating the output of the panel / system the figures achieved would truly mean something.

In Germany they have a minimum standard which is enhanced by the blue angel award, if SEI and possibly other authorities worked with us we should be able to provide a genuine rating for each product on the Irish market.

quentingargan

PeteHeat wrote: »

Hi Doctor_L,

The devil is in the detail such as the temperature of 60c required at the tap also the figures for the output of the panels are in contradiction to what is the minimum test certified products sold in this country.

I've done BER training with Seamus and found him excellent.

The year-round efficiency of a panel is somewhat different from the efficiency you will find on the certs. A panel may be 75% efficient in full sunshine, but that efficiency falls dramatically if the water temperature is high and the sunshine is down to 300 or 400W/SqM. Then there are pipe lossses, storage losses as are pointed out in the presentation.

You don't want water at 60 degrees to your taps, but water in the cylinder should be raised to that temperature in the cylinder to prevent legionnaires etc.

There might be some figures in there that you would dispute, but that is all part of healthy debate on how you might size a system and what might be an appropriate solar fraction. The presentation is a lot more accurate than the figures I have seen from slick sales presentations made by some businesses in this industry...

There is always a bit of a danger in watching a presentation without the narrative that may qualify certain statements made in the presentation. But this is a useful intro to the subject for those who know n'owt

gizmo555

For me, the most telling part of that presentation is the chart on pg 41 showing actual annual figures for energy collected by a 6 sq mtr flat plate system in 2004 in Waterford (the "Sunny Southeast"!).

The system produced a total of about 1,400kWh in the year. Even if we assume that all the energy displaced is standard rate electricity, after the recently announced price cut and entry of Bord Gais & Airtricity to the market, the present value of this is a whopping €200.

nol6

hi there, we had solar panels installed last year - 6m2 of flat plate and are also using a 300l dual coil cylinder (and gas condensing boiler to heat water when the sun does not shine).

I am orignially form Germany, and am not too impressed with the ignorance of some plumbers here. We had one (who did not install the system) who was suggesting that the tank is too big. It is just right, 50l per m2 of panels.(as I also heard at BER course)

We did go with a company from Cork who do use German and Austian components, as we wanted to make sure that the equipment is of a high standard and has 5-10 years warranty.

Last week we had 70 degree water in the tank, so hopefully we will have a summer this year to make full use of our system.

Nol

Evergreen

It is a very interesting document, but I have to agree with PeteHeat saying that 60°C is way too hot for tap temperature – most continental hotels have a button on the shower control that you have to purposely push to get the temperature past 48°C.

Also, a lot of his data seems to be out of date

• What decade does his system schematic come from? No installer in their right mind uses air vents on a solar loop these days.
• 350-400kWh/m2/yr for flat plate is way off, a good Austrian made panel can achieve 560 kWh/m2/yr with 1000 kWh/m2/yr (1000 kWh/m2/yr covers most of the country with the South East getting slightly higher).
• He rates tube collectors at 400-500 kWh/m2/yr, you wouldn’t want to be touching tubes that delivered anything under 600 kWh/m2/yr and even that is well below average.
• He recommends 4 square meters of flat plate for an average family, at the moment the average is closer to 6.5 square meters and rising. If Ireland follows the growth curve in Austria the average installation will be closer to 10 square meters per hose hold in 5 years time

Not to take away from the guy though, I think he has put a lot of work into this presentation and if it was updated would be very useful