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Confused About Epever Controller Specs on Max Wattage

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Gibsito

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Nov 5, 2022
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I'm planning a 400w solar setup for my 5th wheel and am confused about solar panel and controller compatibility. I am looking at four HQST 100w mono panels (to be wired in parallel) and an EPEVER Tracer 3210AN MPPT controller (30A, 100V).

The specs in the listing for the controller say max PV input is 390 watts @ 12v. Since I am wiring these panels in parallel this concerns me, since it's 400 watts combined. The max volts and amps will be way below the limits for this controller so I don't understand why 390 watts is the input limit. Is this something I can safely ignore, since due to all the inefficiencies associated with PV systems it would likely not exceed 390 watts anyway? And even if the max system watts is exceeded, the controller will simply operate at the rated power level?

Panel specs: Voc=24.3v, Isc=5.34a, Vmp=20.3v, Imp=4.93a.

Thanks for any advice. I've put two RV solar systems together in the past (13 years ago and 2 years ago) but I still have more to learn.
 
I don't think you'll have any problems, the 390w figure just indicates how much power the Tracer can deliver according to the maximum current it can handle at a given voltage. Its firmware will self regulate and prevent an overcurrent situation. The total maximum PV power for the 3210AN at 12v is 580w, you're well within safe limits.
To add to this, you'll very rarely (if ever) encounter the situation where the panels are delivering 100% of their rated output.

A word of warning: when connecting more than 2 panels in parallel you'll generally need to fuse each. Check the maximum series fuse rating and configure accordingly, or consider a 2S2P setup, which will give you a more efficient system if the panels can be oriented in pairs.
 
2S2P is definitely the way to go if possible. With 2 in series the charge controller will reach the minimum start up voltage earlier in the morning and have much better output on marginal days with a lot of cloud cover. With a 4P panel connection the performance will be marginal under most conditions other than perfect clear skies.
 
Thanks for the replies, greatly appreciated. I am going to use the 2s2p configuration so thanks for suggesting that. It does make a lot of sense. The Panels are mounted and connected to each other, and now I need to complete the wire run down to the charge controller. Lots of fun. I really enjoy putting these systems together.
 
MisterSandals said:
Is there any particular reason you are looking at small panels and not something like a single 400W panel or a couple 250's?
Click to expand...

I was going to ask something similar. I started out with ~2.5 kW of those smaller 100 watt panels (Renogy and HQST), but I'm less stoked about them these days.

They're great in some ways because they're easy to move around, but you have to be careful because brand and model # aren't necessarily enough to guarantee matched panels.

Another challenge is you'll need more mounting hardware and the efficiency may be a bit lower than newer/larger top-of-the-line panels like MisterSandals is referring to. On the other hand, certain roof geometries may only be possible to fill very optimally with smaller panels - particularly if there are obstacles like vents or antennas.

Finally, the best price/watt you'll probably get with the 100watt panels is around $0.70 - $1.00 per watt whereas with larger panels bought through SanTan (as an example) you might be able to get in the range of $0.30 - $0.60 per watt.
 
Pete@SolarBatteryBarn said:
with larger panels (over 300W) in a mobile installation?
Click to expand...
Take a look thru the Show and Tell area, like this one (455W panels on 5th wheel)

diysolarforum.com

EG4 5th Wheel RV Solar Design

Looking for a once over of my blueprint for my 5th Wheel before buying everything if anyone is willing. Rig is wired for 50 amp, 38 feet, 3 A/C's, and good carrying capacity for all the equipment. I live in Arizona with lots of sun. I am not changing my breaker panel I am simply replacing L1...
diysolarforum.com diysolarforum.com
 
octal_ip said:
The total maximum PV power for the 3210AN at 12v is 580w, you're well within safe limits.
Click to expand...

Actually when you read the Epever Tracer AN manual very closely you will see that the figure "1.5x" the maximum charging power is given as a "suggestion" as they do not wish for you to waste money on excessive over-paneling. I interperate this paragraph as that there is NO specific maximum per se, as long as one stays under 100v.

wasted-pv.png
 
Often 100w panels just fit better on RV roofs that have A/C units, vents, other obstructions. Sure they are more expensive per watt, but it might be worth it if you can cram more solar surface area on the roof. YMMV.
 
Bigger watt panels are often more difficult in buying 1 at a time. Shipping is more difficult due to size, installing can be harder and often the price per watt is higher than discount 100w panels (that you can get free shipping on).

Now if you can drive to the place of purchase and somebody has a bargain on used panels or even new large ones your calculations of what might be best changes.
 
Symbioquine said:
I was going to ask something similar. I started out with ~2.5 kW of those smaller 100 watt panels (Renogy and HQST), but I'm less stoked about them these days.

They're great in some ways because they're easy to move around, but you have to be careful because brand and model # aren't necessarily enough to guarantee matched panels.

Another challenge is you'll need more mounting hardware and the efficiency may be a bit lower than newer/larger top-of-the-line panels like MisterSandals is referring to. On the other hand, certain roof geometries may only be possible to fill very optimally with smaller panels - particularly if there are obstacles like vents or antennas.

Finally, the best price/watt you'll probably get with the 100watt panels is around $0.70 - $1.00 per watt whereas with larger panels bought through SanTan (as an example) you might be able to get in the range of $0.30 - $0.60 per watt.
Click to expand...
Well - honestly, I went with what I knew from previous installations, and thought I would have to split these panels up to different parts of the roof due to vents, etc. But as it turned out I did find a spot where I could mount them all together, so a single 400w panel probably would have worked just fine. Too late now, as the other panels are already mounted.

But I took a look at San Tan just to see what I could have saved and they have a 410w panel that would have saved me $87 over what I paid for the 4 HQST panels. There were cheaper options that were blemished but I was leary about that. But the shipping cost was astronomical and would have more than wiped out any savings - much more. The cheapest shipping option I saw would have pushed the price up from $269 to $632. Yikes! Is there something I'm missing regarding shipping? I got the HQST panels on Amazon with free shipping.

I also looked at sunelec.com where I bought panels for my first system 13 years ago and they too had great prices. There was a 410w panel there for $238, a $118 savings over what I paid. But I never got as far as figuring out the shipping cost because apparently they don't sell individual panels there anymore. The minimum order was a 31-panel pallet.
 
Last edited:
Gibsito said:
Yikes! Is there something I'm missing regarding shipping?
Click to expand...

The only thing would be that you should try calling SanTan (if you haven't already) and get a quote for panels + shipping if you think some might be a good fit for you. In the past the shipping/freight price on the website wasn't really that good of a predictor of the actual cost for me. It might still not make sense, but it's worth a try anyway.
 
Symbioquine said:
The only thing would be that you should try calling SanTan (if you haven't already) and get a quote for panels + shipping if you think some might be a good fit for you. In the past the shipping/freight price on the website wasn't really that good of a predictor of the actual cost for me. It might still not make sense, but it's worth a try anyway.
Click to expand...
Thanks for the advice. I'll give that a try next time I'm putting a system together. But if that is the case, it would definitely be in their best interest to make that shipping estimator more accurate so they don't lose sales over it.
 
Gibsito said:
I'm planning a 400w solar setup for my 5th wheel and am confused about solar panel and controller compatibility. I am looking at four HQST 100w mono panels (to be wired in parallel) and an EPEVER Tracer 3210AN MPPT controller (30A, 100V).

The specs in the listing for the controller say max PV input is 390 watts @ 12v. Since I am wiring these panels in parallel this concerns me, since it's 400 watts combined. The max volts and amps will be way below the limits for this controller so I don't understand why 390 watts is the input limit. Is this something I can safely ignore, since due to all the inefficiencies associated with PV systems it would likely not exceed 390 watts anyway? And even if the max system watts is exceeded, the controller will simply operate at the rated power level?

Panel specs: Voc=24.3v, Isc=5.34a, Vmp=20.3v, Imp=4.93a.

Thanks for any advice. I've put two RV solar systems together in the past (13 years ago and 2 years ago) but I still have more to learn.
Click to expand...
All four panels in parallel and they have a combined short circuit current of 21.36A (5.34A x 4) and if your SCC has a maximum PV input current of 30A per the manual under test conditions, there is no over-current problem. You are good to go.
 
guidecca said:
All four panels in parallel and they have a combined short circuit current of 21.36A (5.34A x 4) and if your SCC has a maximum PV input current of 30A per the manual under test conditions, there is no over-current problem. You are good to go.
Click to expand...
Agreed, and even adding an extra 25% for "edge of cloud effect" it's at 26.7A, still below the 30A current threshold. So I couldn't understand why the controller would have a 390 watt limit. But I guess if input exceeds that it will just be ignored anyway, so it shouldn't be an issue.
 
Im using 3210AN with 470W solar panel and 12V battery at several day. When is sunny and during charging at max 30A, two times charging stop. Controller shows PV voltage but no charging 0A. When reconnect the panel charging start again. From what is this problem, maybe some protection or faulty charger
 
I have an EPEVER 6420AN (rated for 60A) but I noticed it always tops out at about 53 amps. There is plenty more power available with 4380W of panels (~75A) and it gets to 53 amps fast and then throttles it there.
Is this typical?
 
Pete@SolarBatteryBarn said:
There is plenty more power available with 4380W of panels (~75A) and it gets to 53 amps fast and then throttles it there.
Click to expand...
4380W / 75A = 58V

Your SCC needs your array voltage to be about 5V over battery charging voltage. So if your array is 58V, if it stops charging at 53V that makes sense.

Why oh why is your array configured to produce minimal volts and absurd amps?
Can you describe your panel specs and how its wired?

Hopefully you are not pushing 75A thru MC4 connectors. And hopefully with many many strings (i suspect) in parallel they are properly fused.

Sounds like your array can be made a LOT better.
 
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