I have a few question to ask I am thinking of installing a dc-dc charger as near as possible to my 2 x 120ah calcium house batteries .because when we travelling I don't get a full charge I also thinking of putting 450 watt solar on the roof iknow when we travel the solar will charge the battery's .at the moment I have 180 watt portable which barely charges when we free camp.my next question are the flexible panels any good or do they need air flow .i know they are a lot lighter but I only want to do the job once .i would probably keep the portable because I would not get any money for them if I sold them
Hi Trevor, I will pass on what I know from my experience, I have 1,200W of flexible solar on the roof of my van, it works well, and yes its efficiency drops as the panels get hot. If I was doing it again I would tackle mounting the panels a little differently.
When I first got my panels I tested them in the sun, and they get very hot, up around 75 degrees C on the back of the panel. I did not want this heat going in to the roof of the van, so I sat the panels on top of 10mm of foam insulation, this saved the roof of the van, but the panels still get hot.
If I was doing it again, I would get some metal mounts bent up that would sit the panels maybe 20mm above the roof, this would keep the heat away from the roof, and it would allow an air gap to cool the panels a bit. They will still get hot you just can not avoid that.
BTW, at 75 degrees C the panels should stilll be about 83% efficient which in my case is tolerable.
The panels are significantly lighter, at 1.3kg per 100W, compared with about 12kg per 100w with conventional glass fronted panels.
I am not qualified to comment on the DC to DC charging from the tow vehicle, as I do not worry about how well it works, I just leave it to the solar.
Thanks for your input .I will have to look in to the panels a bit further as the weight of them is a lot to think about .But the heat of them needs a lot of thought .thanks again
