When we bought our Airstream Flying Cloud 23FB last year, we had the dealer add the Airstream solar option. That was a single 80 watt (6.67 amps) solar panel mounted on the roof. It is really nice, and we want to increase it. I see that the solar controller is rated up to 25 amps. Since 3 panels (240 watts) at 12v is 20 amps, the controller should handle it.However, looking at the wiring diagram, it looks like the wire from the panels to the controller is 10g wire fused at 10 amps. The wire from the controller to the battery buss is 12g wire fused at 10 amps. If we go to 3 panels, the 20 amps of charge are way too much. Even if we only go to 2 panels, the 13.34 amps is too high.Can we bump our solar up? And if so, how high? We REALLY want 3 of those 80 watt solar panels on the roof.

You'll have to increase your wire size or go series and get a controller to handle the voltage.

Why is the panel-controller wiring fused @ 10 amps? Replace the fuse with a 30. On the controller-battery wire, replace it. It should be a short run, anyway.

An 80w panel normally has an Isc of about 5 amps, which is what you would expect to see with it aimed right at a high sun. 6.67 amps if that is what you are seeing at the battery, could mean you have an MPPT controller with the batts very low to get that many amps, or else your panel is more like 110w. with an 80w panel, you would normally have a simple PWM controller.Anyway, yes you can increase the solar. But first confirm which controller you have now by brand and model, and also if you can, which panel you have. Then we can spend all your money on suggested upgrades. :)

#10 wire? +1 for just increasing the fuse. Actually you can just delete the fuses as the panels will never generate enough to be an issue. 30 or 40 amp fuse near the battery is all you need.Increase wire size only if you find you are not getting the power you expect and it is due to voltage drop in the wire.

All of this information is coming from the Airstream schematics. The TT was pre-wired for solar like this. Now, replacing that 12g wire from the controller to the battery is doable. They are in the same, easily accessible, compartment.

Wanting to increase our solar | Good Sam Community

19 Replies

BFL13
Explorer II
Oct 29, 2018
What is the brand and model of the controller? It matters if it is MPPT or PWM for expanding the array. MPPT has amps limiting so you can "over-panel", but PWM requires some "margin" to stay under its rating when the panel does more than its Isc at times. It will heat up and fry if over-amped for a length of time.

You need the specs of the panel you have before getting more. Info so far on that is not correct as presented. Where did that 6.67amps come from? If you saw that at the battery, then for sure the panel can do more than that. How much more? Three times the mystery amount could be more than the controller can do.
pianotuna
Nomad III
Oct 29, 2018
I would replace the 10 amp fuse between the panel and controller with a dc rated disconnect switch.
theoldwizard1
Explorer II
Oct 29, 2018
Fuses are "odd". A 10A fuse will happily pass 15A of current for a MINIMUM of 60 minutes !

10 AWG should easily be able to handle 30A, and 12 awg can easily handle 20A.
BFL13
Explorer II
Oct 29, 2018
Bobbo wrote:
All of this information is coming from the Airstream schematics. The TT was pre-wired for solar like this. Now, replacing that 12g wire from the controller to the battery is doable. They are in the same, easily accessible, compartment.

Ignoring the schematics, how did you measure that 6.67 amps from an "80w" panel? You might not have the solar you think you have.
Bobbo
Explorer III
Oct 29, 2018
All of this information is coming from the Airstream schematics. The TT was pre-wired for solar like this. Now, replacing that 12g wire from the controller to the battery is doable. They are in the same, easily accessible, compartment.
time2roll
Nomad
Oct 29, 2018
#10 wire? +1 for just increasing the fuse. Actually you can just delete the fuses as the panels will never generate enough to be an issue. 30 or 40 amp fuse near the battery is all you need.

Increase wire size only if you find you are not getting the power you expect and it is due to voltage drop in the wire.
BFL13
Explorer II
Oct 29, 2018
An 80w panel normally has an Isc of about 5 amps, which is what you would expect to see with it aimed right at a high sun. 6.67 amps if that is what you are seeing at the battery, could mean you have an MPPT controller with the batts very low to get that many amps, or else your panel is more like 110w. with an 80w panel, you would normally have a simple PWM controller.

Anyway, yes you can increase the solar. But first confirm which controller you have now by brand and model, and also if you can, which panel you have. Then we can spend all your money on suggested upgrades. :)
Darryl_Rita
Explorer
Oct 29, 2018
Why is the panel-controller wiring fused @ 10 amps? Replace the fuse with a 30. On the controller-battery wire, replace it. It should be a short run, anyway.
2oldman
Explorer II
Oct 29, 2018
You'll have to increase your wire size or go series and get a controller to handle the voltage.

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Wanting to increase our solar

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