Fixed Solar Panel on Renault Master Van
Submitted: Monday, Apr 18, 2022 at 19:09
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Kris K
Hi All,
I currently have a folding 250 watt solar panel, which is heavy/bulky but works very
well.
I'm considering mounting a fixed larger panel (or 2) on the top of the van. The issue will be, its flat and won't be angled.
How much of an issue is this as opposed to my portable panels which I move around during the day and are tilted.
Will be keeping a pair of AGM Giant 190AH batteries topped up
Thanks!
Reply By: nickb - Monday, Apr 18, 2022 at 21:10
Monday, Apr 18, 2022 at 21:10
I have 2x 120W solar panels mounted on my Jayco Dove connected to a 105Ah battery. Runs a 57L fridge, various lights, charges devices etc. When we
camp in summer and there are no clouds the battery is in float mode before 10am. We did a 6 week trip and the camper was never connected to 240V or to the car's charging system and we had no issues. A couple cloudy days in a row is about the limit though!
Would be better if you can get a bit more solar wattage up there to compensate for the flat installation. Also, those thin solar sheets don't seem to last more than a couple years, stick to standard style panels.
AnswerID:
640243
Reply By: swampy - Tuesday, Apr 19, 2022 at 00:18
Tuesday, Apr 19, 2022 at 00:18
hi
200watts per 100/120ah battery is a good ratio .
Flat will not matter unless u park in the shade . Best idea is to have 1x fixed and 1x portable set . And Always measure your panels amp output at 12.00 miday when sun is most vertical . Why ? Some cheaper brands do not produce anywhere near what they claim . 200watts puts out 11amps with out Mppt and 14 with Mppt .
Wire panels in parallel to avoid panels shutting down from shade .
The further south u in Aust. you are and the closer to winter u are the less charge u get .
AnswerID:
640245
Reply By: Member - McLaren3030 - Tuesday, Apr 19, 2022 at 09:05
Tuesday, Apr 19, 2022 at 09:05
Hi Kris,
For that amount of battery capacity, you really need about 800 watts of Solar Capacity. A good rule of thumb is that for every battery amp you have, you need double the watts of solar capacity. This is even more important if the panels are fixed roof mounted, as they will not be at an appropriate angle to the sun. This means that you will need a fair amount of roof space to mount 4 x 200 watt panels.
I agree with you with regard to portable panels being heavy and bulky, however their ability to “chase the sun” is a redeeming feature. Have you thought about changing over to a folding blanket instead of folding panels? They are much lighter, and fold up much smaller.
Whichever way you decide to go, you definitely need more solar capacity for that amount of battery capacity.
Macca.
AnswerID:
640249
Follow Up By: Kris K - Tuesday, Apr 19, 2022 at 16:14
Tuesday, Apr 19, 2022 at 16:14
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.
FollowupID:
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Follow Up By: Peter_n_Margaret - Tuesday, Apr 19, 2022 at 16:31
Tuesday, Apr 19, 2022 at 16:31
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
FollowupID:
919341
Follow Up By: Member - McLaren3030 - Wednesday, Apr 20, 2022 at 07:42
Wednesday, Apr 20, 2022 at 07:42
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.
FollowupID:
919346
Follow Up By: Kris K - Wednesday, Apr 20, 2022 at 07:55
Wednesday, Apr 20, 2022 at 07:55
Thanks all, Ive got my head around it now :)
FollowupID:
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Reply By: Peter_n_Margaret - Tuesday, Apr 19, 2022 at 16:08
Tuesday, Apr 19, 2022 at 16:08
"The further south u in Aust. you are and the closer to winter u are the less charge u get ."
Not necessarily........
1. Further south is cooler and panel efficiency is higher.
2. Further south the day is longer.
In fact, the most difficult area to maintain full charge is in the tropics because the fridge loads are much higher and if it also rains or there is cloud cover there is a double whammy.
Winter down south can be a challenging issue. Have the alternator capable of charging the batteries.
Solution? Install as much solar as will fit. It is cheap and apart from weight, there is no down side.
We have toured
well north of the arctic circle in Norway. Maintaining batteries via solar was never a concern. Cool, low loads and 24hour sun. We were still getting a dribble of power at midnight.
Cheers,
Peter
OKA196 motorhome
AnswerID:
640260
Follow Up By: 1392 - Friday, Apr 29, 2022 at 18:09
Friday, Apr 29, 2022 at 18:09
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.
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