V(oc) on solar panels

[mike-uswest]

Well I found a 2016 used TT, Arctic Fox 25Y. It has 2-100 Watt Zamp panels that were installed by the dealer, with a Zamp controller. I was told that it has 8 AWG wiring with three connections. I have read somewhere that in adding panels of different types the V(oc)should be close in value. I have found a Grape 160 watt panel for $155 used that has a V(oc) of 22.4. I have not been able to find anything on the Zamp panels. They are all 12 volt. How close do they have to be on the V(oc)? Thanks for any information.

Mike

[mike-uswest]

I ended up calling Zamp solar, and they gave me the specs. They are very close on the Voc and the Vmp. So I will try to get it. Thanks for the answers.

Mike

[BFL13]

All the panels will be at battery voltage (so the same voltage) when connected using a PWM controller. They will add their amps ok at least up to 15v. You get amps at Isc value in full sun, fewer amps when panels are flat on the roof with sun not right above.

MPPT is different, where it tries to use a single Vmp. With PWM, Vmp is meaningless.

There might be some losses mixing mono and poly but not much AFAIK.

With the two 100s at 6.2 each Isc and the 160 at say 10 amps you will want a 30 amp controller (needs some amp margin for when panels go above ratings at times) and the panels in parallel (not series with PWMs which can't take the high added Vocs)

#8 wire should be fine within reasonable lengths. Suggest a Grape 40 amper as the new controller. (good price and room for more panels at the 40 than with a 30)

[scrubjaysnest]

To answer your question, Voc should be within 10%. I have used 18.9 volt(Voc) with 21 volt (Voc) with no measurable difference in full sun when the 18 volt panel was added.

For series operation the current must be within 10 % also and the lowest rated Imp will determine the array output.

[MDKMDK]

If it's the same ZAMP system that Winnebago adds to the new Views/Navions, I think there's a maximum panel output wattage/amperage going into any one port of the 3 port combiner on the roof, and a maximum overall wattage limit to the charge controller of around 500W. That number also includes a temporary/portable input port at ground level with a maximum input wattage equal to the remaining capacity of the system. I may have that wrong. I don't have the exact numbers.
ZAMP would be able to confirm this for you.

[MrWizard]

i would thing Vmp is more important but both should be as close as possible

[Ed_Gee]

mike-uswest wrote:
Well I found a 2016 used TT, Arctic Fox 25Y. It has 2-100 Watt Zamp panels that were installed by the dealer, with a Zamp controller. I was told that it has 8 AWG wiring with three connections. I have read somewhere that in adding panels of different types the V(oc)should be close in value. I have found a Grape 160 watt panel for $155 used that has a V(oc) of 22.4. I have not been able to find anything on the Zamp panels. They are all 12 volt. How close do they have to be on the V(oc)? Thanks for any information.

Mike

Having some experience with both Grape and Zamp panels, I suspect you will have no problem with compatibility. The only issue you should first check on is the power handling capability of your controller.