Solar panels are used nowadays by more and more people, looks almost like a fashion to install a solar panel on the rooftop of your house. People get more interested in installing a photovoltaic system, maybe not to be environmental friendly, but mostly to reduce energy costs. For many the cost of the system is the trigger not to install photovoltaic panels which are still extremely expensive. A solution in this cause would be the solar water heaters which can save as much power as the photovoltaic panels but with lower installation cost.
The lower costs are usually also driven by the efficiency percent of the solar water heater. An Irish company called Surface Power claimed and proved that their system is more efficient than others you can find on the market in this moment. Surface Power even claimed and received independent certification from TUV Rhineland that their solar water heaters are at least 131% more efficient in the morning and evening, and 76% more at midday that other solar heaters. In this way the payback time for the system is reduced by 50% but it depends as well on how much the sun will expose the system.
Surface Power says that their new panels have the potential to reduce domestic and commercial hot water bills up to 70% and this because of the advance technology used. The system isn’t much more expensive than the other systems either so it’s highly recommended and will probably be installed on many houses.
Surface Power is still a small company and does not have a large market yet. As well most people probably think to better install photovoltaic panels but the solar water heater made by Surface Power has a lot of potential.
Thanks for sharing such a valuable information.
thanks a lot for lots of information on swh .here i m the startup in renewable energy energy efficiency business. searching for a low cost and compact and durable swh for sale in india. any body have it pl share.
Hi guys,
I checked out Jiangsu Sunpower Solar on the Made-in-China website and was astounded by the amount of different solar water heating systems available. Could anyone explain which system offers the best value long term.
Airier India – the Leading manufacturers, suppliers and exporters of Industrial ventilator, Wind turbine ventilator, Turbo ventilator, Turbine ventilators, Rooftop ventilator etc. in India.
Come to think of it. If I had to return to using the immersion heater for heating water (haven’t switched it on since November and don’t expect to..) and my family’s new higher level use of hotwater were to continue… I don’t think I would be able to retrain them back to econimising on the hotwater… then it would cost an absolute fortune in electricity bills. On this basis and with the first batch of kids heading for their teens then by the time they are shipped off to college I suspect the solar’s will have paid for themselves. Less stressful too.
Came across this thread when looking for information about Surface Power last November.
Irish Engineer’s statement “Annual yield per square metre of actual panel is the only way to compare panels as this is what matters at the end of the day.” made me smile and say think – No.
What matters is how much hotwater you need and how much it’s going to cost you to install.
I should state first off that I went for the Surface Power panels after comparing prices, yields and reading a fair amount of waffle and detail that the average punter has no interest in tackling. The media hype on Surface Power power – “130% more efficient” etc..- gives them great publicity but when they fail to counter this hype by clarifying that it is only a best versus worst comparison of the TUV results, and when they post results from customers showing photos of collectors at over 50 degrees on a foggy day, they lose credability.
Surface Power will give you hotwater at over 50 degrees in the shortest days of winter but only if you you haven’t a big demand drawing in fresh cold water. If you only use less than say 100 litres per day then you’ll see great results and frequently hit into the 40’s and above. If you have such a low demand then solar panels are probably not justifiable financially but they will give you plenty of green boasting brownie points.
Back to Irish Engineers statement,re the annual yield per square metre of actual panel: this might be true for those who have a very limited amount of roof space, but what will matter to most is how much hotwater will I get for my Euro and will I be happy with the results.
Paying out close to €6,000 for solar panels and “free” hotwater is not financially justifiable.
However that kind of money would buy you 300l hot water cylinder tank and either circa 4 sqr metres of tubes or 6 sqr metre of flat(aperture area) which are close enough equivalent yield in the good quality brands. The 300l cyclinder is a great jog if you have a big family and a big demand on hot water. In fact I would now consider it essential, especially a triple coil. Works brilliantly with the two upper coils fed from the boiler. So you could say that the €1,500 or more of the cost associated with the cylinder is an every big family should have one anyway cost. If we assume that you have a medium size household then 4m of tube or 6m of flat is probably enough, then you would be as welll to go for the 6m of flat and get 6 panel grants..i.e. €1800 grant if it was 6m aperture. This would leave circa €2,700, perhaps closer to €2,000 is possible if getting a very good price, for the cost of the solar panels.
On this basis you could perhaps financially justify the expense of solar panels.
Of course money isn’t everything.
Having a happy family and not worrying too much that there’s hot water in the house, that the hot water tap is left running and showers take half an hour and over 100l a go… these all count towards justification.
If you use a lot of hotwater get a 300 l cylinder.. they are brilliant… a must have for a big family. A medium family would probably be alright with 6m of flat. A bigger family might want to go for 6m of tubes, but keep an eye out for yield per € and bargain hard.
If you don’t use much hot water …say 100l.. perhaps it might be worth considering something like a Willis Solar syphon. Flat would probably be good enough if facing south.
If you have a family like mine that let’s the hot water tap run and a shower takes half an hour…then don’t expect to save a lot of money … but do expect to enjoy having plenty of running hot water, be it from solar or topped up from the boiler.
Thanks Irish Engineer – certainly interesting.
I note that you have the same form on the EcoEvolution blog.
Hi TopCat,
In the efficiency formula you are concerned about the difference in temperature between the fluid and ambient so just increase the delta by a fixed amount at each graph point.
I compared the top 7 European manufacturers of evacuated tube solar collectors which account for over 85% of the market share by volume, I also compared some others. I found a vast variance in actual performance/yield. Please see attached link showing some of my findings, it compares a number of different panels and shows the Kloben Sky to be the top rated panel that I have come across:
http://www.megaupload.com/?d=SZZYL96X
Hope this is of some help.
Hi Irish Engineer,
Thanks for the info on calculating the efficiency. Like you, I checked the TUV database a few months ago when I saw the Surface Power press releases, and also drew a blank. Since their price is relatively high, I wanted to be sure that the price premium was justified for the claimed efficiency. When I failed to find the independent evidence, I walked away from them as a option.
I am doing a new build, and the choice of solar panel has been causing me some headaches. The various suppliers seem to put in a special effort to make it more difficult to make direct comparisons! From 6 quotes, I only have n0, a1 & a2 data for 3 of them, and the variation was enough to drive me back to Google which is how I came to your post here.
Excuse the possibly stupid question, but in the formula above, do you vary the fluid temp. and keep the ambient fixed when graphing the efficiency ?
Would you mind telling me if you found any particular supplier to be especially good from your own analysis ?
η = η0 – a1*(Tf-Ta)/G – a2*(Tf-Ta)2/G
Just to clarify:
(Tf-Ta)2 in above equation is (Tf-Ta) squared.
Hi Pacman,
Hope all is well in Mayo. Here you go.
η0 = Conversion Factor (zero loss collector efficiency)
a1 = Heat Transfer Coefficient
a2 = Temp dependent Heat Transfer Coefficient
G = Solar irradiance W/m2
Tf = Mean fluid temperature
Ta = Ambient temperature
η = η0 – a1*(Tf-Ta)/G – a2*(Tf-Ta)2/G
Plug the values from the HARP database into this equation and graph efficiency versus temp (Tf-Ta) values, say 20degC to 100degC. Its zero loss efficiency is good but there is no energy generated here as the fluid and ambient temperatures are the same. Its heat transfer coefficients are terrible so the efficiency falls off very quickly with increasing fluid temperature relative to ambient temperature. I have done a lot of research into the different panels on the market and efficiency is only part of the equation. You also have to take into account the aperature area of the panel. Some panels have a particularly low aperature area compared to the gross area of the panel and the Surface Power panel falls very much into this category (0.95/1.69=56%). This means that the annual yield of the physical panel on your roof is quite poor compared to other panels with a high efficiency and a high aperature/gross area percentage(up to 88%). Annual yield per square metre of actual panel is the only way to compare panels as this is what matters at the end of the day. Try some different panels and you will be amazed at the variance. I suggest you compare Surface Power, Ritter, Kloben, Thermomax and Greenline(Xingwang). With the poorer panels you require more panels on the roof to give the same output as higher yielding panels, so for instance a 300L system may only require 2 x 12 tube panels of a high yielding panel verus say 40 or more tubes of a poor yielding panel. Unfortunately people sometimes think they are getting a bargain as they are getting more tubes for their money but in actual fact the annual yield may be lower than with less of the higher yielding panels. Also unfortunately the SEI GHS grant system rewards people for installing more aperature area and not actual high yielding panels.
Interesting subject but unfortunately there are some people involved in the business who have very little, if any, business ethics. By the way, just in reply to Solar Cooker Man’s comment, I am not a disgruntled competitor as I do not manufacture or distribute solar panels.
Hope this is of some help.
Hi Irish Engineer.
Could you help me please, i was wondering how to calculate the efficences of the solar collectors.
Any idia
Well Solar Cooker Man, the proof is in the pudding. Just search the TUV Rheinland site or better still contact SEI directly. Also just look at the figures on the SEI HARP database, based on these figures the panels are far from “the most efficient solar water heater in the world”.
Just plug in the values for the heat loss coefficients and the conversion factor and you can see that it in fact has quite a poor efficiency as the temperature delta increases, couple this with the fact that the aperture area is quite low compared to the gross area of the panel and it is an extremely poor performing/yielding panel. You do not need the TUV cert to see this.
I asked for it and was sent it in the post ? You sound like a disgruntled competitor. Pity we can’t just do business in Ireland without begruging all the time.
Anyone know how to connect a solar panel to a cooker plate or how it could be done, will it work in ireland.?? Any help apprieciated. Can visit if in the cork area.
I would have to agree with Irish Solar. The TUV Rheinland certification number does not exist on the TUV database. The product (SP501) is registered on the Irish SEI HARP database on foot of this TUV certification but its authenticity has now been called into question. I contacted SEI to enquire about its inclusion on their HARP database and they told me that they could not discuss the matter as it was under investigation. I also contacted Surface Power looking for a copy of the TUV certification but was refused. Why bother getting your product independently tested if the test results are not going to be made available to the general public? A very very serious situation for Surface Power, their sharp practice may have eventually caught up with them.
China and Solar technologies: that’s right, 65% of their installed devicesare at the top level! To be compared to 6% in Germany, Europe’s leading country.
Just check http://www.made-in-china.com that’s where the best prices vs. top technology can be found.
Rgds
China and solar power: that’s right! 65% of China’s installed devices are top level technologies. It’s 10 times better than in Germany…Europe’s best country.
No need of further comments: just check http://www.made-in-china.com That’s where the technology comes! Cheaper!
Rgds
Dear Sir,
Please mail me your E-mail address. Then I will send you more product info.
Regards
Jet
Dear Madam, Dear Sir,
I am just creating a company concerning the renewable energies in Paru. I see your solar water heating equipment, I will be interested to receive documents and technical datas to promote it. Please note that very near to the equador and the geographical situation is good for this type of equipment.
My contact is:
Jean Paul ROUX
Los Sauces 315
San Isidro
LIMA – PERU
Tel 00 51 1 221 73 10
Please visit http://www.solar-heating.cn/Product.asp Thats our new products.
Please also visit http://www.solar-heating.cn/Tech.asp
thanks
need more info, please mail to [email protected]
When you visit http://www.solar-heating.cn, you will have better idea on how to use solar energy. We are the leading manufacturer of solar evacuated tube and thermal collector.
Thanks
In order to clarify your comment about saving the same amount of money for solar hot water systems as for PV systems. If you are referring to the savings related to the costs associated with hot water only for either system then you are correct, however the actual savings on your utility bill for a solar hot water system usually ranges from 15% to 30% off the bill while a PV system can go from a 75% savings to being completely off the grid. All of these systems have a number factors that directly affect the savings percentage that can be realized, such as inclination and orientation of the unit to the sun. The real point that I wish to make here is that only you can look out for your best interest and don’t believe the oil, auto or utility companies when they tell you they are looking out for your best interests. Remember, they are trying to keep you as energy prisoners, so that their income never declines, your nest interests have never been their’s. Just a word to the wise. Google me and you will find that using your head is the key to finding any solution.