I have been asked about these panels. Just a question out there for any comments about them, good or bad. My friend is rebuilding a van and what's to use them but he is not sure if they are any good and neither am I. Your thoughts and comments would be greatly appreciated.
briche
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You only live once, but if you live it right, once is enough !!!!!!
I have installed SEMI FLEXIBLE solar panels on my van roof, before I did that I undertook extensive testing of the panels, what I found is:
- Performance wise they appear to be on a par with a high quality traditional glass panel, the ones I used advertise as having a 22% conversion efficiency (high end of range), and they certainly appear to live up to that.
- They weigh considerably less than traditional glass panels (1.3kg for 100W), and they are indeed semi flexible, about 30 degrees of flex end to end.
- Like all solar panels they get hot, in Melbourne summer sun they were getting up to seventy plus degrees, this heat was on both teh front and the back of the panel.
- When I purchased mine they were more than twice the price of traditional domestic panels.
Since I planned to glue the panels straight onto my van roof the amount of heat on the back of the panel worried me, so I have developed a solution that works for me. I have cut sections of foil board insulation (10mm of polystyrene with foil on either side), sealed the edges with tape, and glued these to the back of the panels, we have then glued the panels to the roof. Being a polystyrene sandwich there is little mechanical strength, so I have then mounted the panels down with aluminium zed brackets.
To date they are working exactly as I expected, with my 1,200W of flat mounted panels developing over 700W in a cool wintery sun.
I will be able to tell you more after they have been for a trip north in the middle of winter.
A friend of mine bought a few of them in from China and swears by them.
But he still hasn't convinced me, my biggest concern is the heat they generate and if they are attached directly to the roof of a van/motorhome the roof is going to get very hot.
I recently needed to test a regulator so I put a rigid panel in a frame on the lawn and left it there all day during the test, when I picked it up the grass under it was cooked.
when I tested with the semi flexibles I recognised that the heat issue may be a problem, so I set up a test comparing three scenarios:
1. Bare white roof.
2. Roof with semi flexible panel in direct contact with the roof.
3. Roof with a semi flexible panel sitting on top of a 10mm thick insulating panel (brans foil board, purchased from bunnings).
Testing in Melbourne, in the middle of the day, on a sunny day in summer. The results were as follows:
1. The bare roof climbed took about 40 minutes to climb to 52 degrees, and stabilised at that temperature.
2.The face of the semi flexible panel reached 73 degrees over about 25 minutes, and th face of the panel remained at that temperature. Under the panel, the roof arrived at 73 degrees about five minutes later, and also remained on that temperature.
3. The face of teh semi flexible panel again went to 73 degrees, and I believe although my records are not good enough to prove it, it may have arrived there faster. The back of the panel above the insulation was also on 73 degrees. The roof under the insulation was on 42 degrees, and remained there.
On the first day of testing, I was moving panels etc, and did not leave a test stable for more than an hour. On the second day I did not test all scenarios, but focused on test 3, and I set this up early in the day, and kept it there all day. The sun must have been slightly less strong, as I was seeing temperatures about two degrees cooler, but again the roof under the insulation remained 10 degrees cooler than bare roof. In this case the test was continued all day.
Needless to say, I have fitted insulation under my panels. It did make mounting the panels more complex, but I think it is worth it.
After talking to David (Plendo) about his research as well as the van manufacturer (Coramal) we decided to have the flexible panels bonded directly to the aluminium panel roof.The reasons for this are twofold. Firstly the weight involved in mounting rigid panels with the framing advised by the caravan maker. Secondly we do almost all our travelling during winter so heating of interior of van would not be a problem. Yes we do loose efficiency due to heating but have ample panels for our power consumption. To date three weeks after fitting have not needed any external power input travelling in Vic and southern SA.
Bit of a possible problem with shading from that A/C unit. I suppose angling the van helps somewhat, but pointing E-W would only give you 50% or less power due to the shading.
