Fixed Solar Panel on Renault Master Van

800 watts isn't possible, just means ill need more than a single day to charge the batteries.

Best I can do is a 300-350 watt fixed, with my portable 250watt unit.

Its going into a redarc BMS with red vision display.

I don't agree with the relationship given to solar requirement relative to battery capacity.
Solar requirement is related to power consumption. You need to put in what you took out. It does not matter if the batteries are big and 10% depleted or small and 90% depleted.
Cheers,
Peter
OKA196 motorhome

Hi Kris,

Not being able to fully charge your batteries in a single day is fraught with issues. You need to remember that if you cannot put back into your batteries what you have taken out, you will continue to go backwards as far as SOC is concerned. If you are moving every day and the vehicle is charging the batteries as well, you may be OK. However, if you are stationary, and not able to fully charge using solar, and do not have another method of charging such as a generator, then eventually you will have “flat” batteries. Remember if you are still running electrical appliances such as a compressor fridge, you are still drawing from the batteries whilst you are charging.

As far as Peter’s comment regarding solar capacity is concerned, yes he is correct in that you only need to be able to replace what you took out, plus what you are continuing to take out whilst charging. However, you cannot guarantee when you will have enough direct sunlight, or for how long you have direct sunlight, or if you have your panels at the appropriate angle to the sun. That is why the majority of solar experts, suggest that double the watts of solar per battery AmpHr is the preferred methodology.

Macca.

Thanks all, Ive got my head around it now :)

Further south, the day is longer? Not sure about that. 6am to 6pm is still 12 hours wherever you are, but that doesn't guarantee the sun will, be shining at the South pole mid winter.
The further south you are means the incident angle of the sun to a flat panel increases, thereby decreasing the intensity of solar radiation falling on the surface area of the panel. That definitely equates to reduced solar panel output current. Best PV performance in terms of solar radiation is when the panel is at right angles to the sun. This is not possible with flat fixed installation though.
Mounting onto the roof of a vehicle is best done on roof racks or similar means to allow a decent air flow beneath the panel for cooling - North or South.