Solar panels

[Ca11um43]

Next year I plan on going off-grid around Italy for 2 weeks, as well as some shorter off-grid trips around the UK. My first trip being next month. Luckily it is fairly local but apart from the few bits that the previous owner left in the van, it's not set up or ready to be used off-grid at all. I've already got a Renogy 100a lithium deep cycle battery, and a Renogy 30a DC to DC MPPT charger ready to be installed, so I'm now looking in to solar panels. I have an AFT roof and ideally don't want to block the window/sun roof, so I'm a bit limited on space. How much solar (wattage) would you recommend to have?

I will be running a 12v compressor fridge (JKF50) pretty much 24/7 as well as LED lights, charging phones, the water pump for the sink, 12v TV (occasionally), etc. So nothing major. The solar will only really be a back up in an unfortunate event where I have to stay parked up for a while, and to keep the leisure battery topped up once I'm parked for the evening.

[g8dhe]

Did you ask this on FB recently? Sure I answered the same question recently!
Oh yes https://www.facebook.com/groups/2529055 ... 6711980733

[Ca11um43]

Did you ask this on FB recently? Sure I answered the same question recently!
Oh yes https://www.facebook.com/groups/2529055 ... 6711980733

Yes I did Just getting as many links/ideas as possible, then I'll measure my roof again when I'm next with my Bongo (I took some measurements before but it was a while ago). It failed it's MOT recently, so is off the road and I'm about to start the repairs to get it back for a retest...Need to plan ahead though, as I haven't got much time until my first off-grid trip in the UK!! So I will be starting to fit the electronics at the same time as the MOT repairs. Definitely keeping my busy lol

[Bob]

Geoff is the expert.

[Ca11um43]

I ended up going for a 160w semi-flexi HPBC panel, from Voltanic.solar From my research it seemed to be the most wattage that I could fit on my roof (in a single panel) without blocking the skylight like most people do. They recommended securing it with Sikaflex 522 which I also bought from them. I assumed they would send me a black adhesive (didn't give me an option) since the solar panel is all black and my roof is dark grey, but annoyingly they sent me white So I had to be extra careful to stick it down without any adhesive seeping out the sides and being really visible. But it's on now.

[g8dhe]

If you glue it to the roof then the panel has no ventilation on the rear of it and its efficiency will fall by 20-30% as the rear of the panel heats up.
Much better to arrange direct ventilation to the rear of the panel so that air can circulate (when static) and prevent the loss of efficiency and long term damage to the cells from heat degradation.

Note: I use to suggest the loss of efficiency was 10-20% but the latest panels are even more sensitive and can now loose much more power and long term damage is now beginning to be noticed on house installations where there is insufficient ventilation to the rear of the panels, at present the exact level and types of cells used have not been disclosed in the results obtained. See here https://www.exponent.com/article/sheddi ... egradation

[Ca11um43]

If you glue it to the roof then the panel has no ventilation on the rear of it and its efficiency will fall by 20-30% as the rear of the panel heats up.
Much better to arrange direct ventilation to the rear of the panel so that air can circulate (when static) and prevent the loss of efficiency and long term damage to the cells from heat degradation.

Note: I use to suggest the loss of efficiency was 10-20% but the latest panels are even more sensitive and can now loose much more power and long term damage is now beginning to be noticed on house installations where there is insufficient ventilation to the rear of the panels, at present the exact level and types of cells used have not been disclosed in the results obtained. See here https://www.exponent.com/article/sheddi ... egradation

I just went by what the company suggested, and stuck it down directly to the roof with Sikaflex 522. I have seen some very old posts about people using thin polycarbonate underneath the flexible panels to increase air flow, but again, I just went by what the company told me and assumed that these panels would have been improved since then. Because I was sent white adhesive, I didn't quite go to the very edge of the panel. I put a thick bead about an inch in from the edge and squished it all down once the panel was in place, so it will probably get a bit of air flow around the edges; just not to the very middle. Spec wise it's similar to the Renogy flexi panels (which I was going to get), and claims to have a 25.8% efficiency rating.

Looks wise I'm VERY happy with it. With it being an all black panel on a dark grey roof, it all blends in. As well as it being so thin, so down on the ground with the AFT closed the only thing you can see is the cables at the back. Other than that you can't see it at all (until the roof is up), which is what I wanted.

I will NOT be relying on solar very often. I don't like to stay in the same place for too long, so I will constantly be moving and my 100ah lithium leisure battery will mainly be charged by the DC to DC MPPT charger while driving. I also won't really be powering much that will drain the battery. The main thing that will be on 24/7 is a compressor fridge. The rest will just be occasional things like LED lights, water pump for the tap, charging phones, etc (It will all be 12v). So the solar is literally just a back up and/or just to keep both batteries topped up while parked, because I believe that once my leisure battery is full my MPPT charger will also keep the starter battery topped up if needed as well. From memory.