Over paneling Rover 40A

[wp12kw]

I have been using 6 100w Renogy panels with my 40A Renogy Rover to charge a 280Ah 8s 24v battery and a Giandel 4000w inverter, and they aren't getting the job done. I have acquired some Stion STL-145 (79 VOC 2.6ish A) and was wondering if over paneling is possible, and just how much over paneling the Rover can handle? Running them in series would make the voltage about 140ish accounting for voltage drop. I'm pretty sure that is too much.
Would it be feasible to combine mismatched panels to more closely match the Rover voltage limit of 100V?

 

[sunshine_eggo]

Over-paneling is about more POWER on the controller than it can handle. It's NEVER about exceeding voltage or current limits.

Your series Voc can NEVER be above the controllers voltage limit, and you typically need 10-20% head room for cold temperature effects. This should be checked for your conditions. If voltage exceeds the limit, you risk destroying the unit. Voltage is a hard limit.

It's a much debated topic, but you also don't want to exceed the PV input current limit. Many controllers do not publish this, so it is assumed to be the same as the output limit, i.e., 40A in your case.

So if your array Voc is 10-20% below limit, and your array Isc is < 40A, you should be good. you can also play with these. if your array is split into parts, e.g., E, S and W facing strings where it's impossible that the total Isc of the panels can exceed 40A, at the same time, you're good.

Worth digging deep into the manual to see if it addresses over-paneling.

 

[wp12kw]

Over-paneling is about more POWER on the controller than it can handle. It's NEVER about exceeding voltage or current limits.

Your series Voc can NEVER be above the controllers voltage limit, and you typically need 10-20% head room for cold temperature effects. This should be checked for your conditions. If voltage exceeds the limit, you risk destroying the unit. Voltage is a hard limit.

It's a much debated topic, but you also don't want to exceed the PV input current limit. Many controllers do not publish this, so it is assumed to be the same as the output limit, i.e., 40A in your case.

So if your array Voc is 10-20% below limit, and your array Isc is < 40A, you should be good. you can also play with these. if your array is split into parts, e.g., E, S and W facing strings where it's impossible that the total Isc of the panels can exceed 40A, at the same time, you're good.

Worth digging deep into the manual to see if it addresses over-paneling.

Thanks for the clarification
I found a good deal on the Stion panels from a large solar farm being disassembled ($.42/W delivered to my location), so I will look at multiple parts/directions.

How could/would I configure the Renogy 100W (22V 5A) and Stion 145W (76ish V 2.6A) panels together to bring the VOC closer to the 100V 40A limit of the SCC? Would the mismatched panels play well together, or is this not feasible?

 

[sunshine_eggo]

Thanks for the clarification
I found a good deal on the Stion panels from a large solar farm being disassembled ($.42/W delivered to my location), so I will look at multiple parts/directions.

How could/would I configure the Renogy 100W (22V 5A) and Stion 145W (76ish V 2.6A) panels together to bring the VOC closer to the 100V 40A limit of the SCC? Would the mismatched panels play well together, or is this not feasible?

Unfortuantely, the two different panels will not perform well together at all. Their Voc values need to be very similar for them to be in parallel, and their currents need to be nearly identical when in series.

There's no combo of Renogy panels that allow you to hit 76V. You're either 66V or 88V.

It may make more sense for you to get a cheap 30A PWM contrller and configure your Renogy panels for 2S3P and then panel the crap out of the MPPT with the Stion panels.

Following my "logic", you could have a 15P array on that 40A controller - about 2X what it can charge at 24V.

 

[Dynoman]

Thanks for the clarification
I found a good deal on the Stion panels from a large solar farm being disassembled ($.42/W delivered to my location), so I will look at multiple parts/directions.

How could/would I configure the Renogy 100W (22V 5A) and Stion 145W (76ish V 2.6A) panels together to bring the VOC closer to the 100V 40A limit of the SCC? Would the mismatched panels play well together, or is this not feasible?

Check out these PDFs. They may be of some help. The Over-paneling document is a really good document from FilterGuy on this forum. There are many good documents in the Resources section of this forum. Click Resources at the top of the page and check it out.

 

[SoakedUp]

I have my Renogy rover 40 paired with 4 320w panels in a 2s2p configuration (~80v VOC, ~20a ISC), charging a 12v system. Manual says 550w max solar for 12v. Been working fine but the controller does get hot running at 40amp output for longer times. I’m using a fan on a schedule directly pointed at the controller to keep temps reasonable. My guess is the controller won’t last long operating at 100% it’s capacity for extended periods.

 

[chrisski]

How could/would I configure the Renogy 100W (22V 5A) and Stion 145W (76ish V 2.6A) panels together to bring the VOC closer to the 100V 40A limit of the SCC?

The only effective solution I found for this is a second SCC. One for the Renogy and one for the Stion. In my head math says for a 12 volt system, a 40 amp controller may allow 3 to 4 panels on a 12 volt system or twice that on a 24 volt system.

Would the mismatched panels play well together, or is this not feasible?

In my signature block there is a “mismatched panel” link that has some math that will let you calculate some scenarios.

On a different forum, someone had a build done by an inexperienced contractor, and among the mistakes the contractor made was putting a 100 watt “helper” panel with a 300 watt panel. Once the 100 watt panel was removed power output went up significantly. The math in the link will explain why.

 

[Dynoman]

I have my Renogy rover 40 paired with 4 320w panels in a 2s2p configuration (~80v VOC, ~20a ISC), charging a 12v system. Manual says 550w max solar for 12v. Been working fine but the controller does get hot running at 40amp output for longer times. I’m using a fan on a schedule directly pointed at the controller to keep temps reasonable. My guess is the controller won’t last long operating at 100% it’s capacity for extended periods.

Using a 12 volt system the Rover 40 rated at 520 watt panel input is significantly over-paneled with 4 x 320 watt panels. Also a lot of lost PV input. Suggest a 2nd 40 amp controller and split the panels between the 2 controllers. Another option would be a 24 volt system.

If these options are not possible suggest running 2 x 320 watt panels until a change is made. As you suggest the Rover 40 will probably burn up the way it is configured.

 

[SoakedUp]

Using a 12 volt system the Rover 40 rated at 520 watt panel input is significantly over-paneled with 4 x 320 watt panels. Also a lot of lost PV input. Suggest a 2nd 40 amp controller and split the panels between the 2 controllers. Another option would be a 24 volt system.

If these options are not possible suggest running 2 x 320 watt panels until a change is made. As you suggest the Rover 40 will probably burn up the way it is configured.

It’s actually not too bad. My panels are laying flat on top a shipping container so their efficiency is already greatly reduced. Probably by at least 40%. They are also in a very dusty environment with little to no rain. The panels will go 2-3 weeks with out anyone there to clean the panels so that probably takes another 10% off. So realistically my 1280 watts of panel is only capable 640-700 (at peak solar) watts which isn’t too much over the max 520 watts. My batteries are usually full by 11-12pm and have already gone into float so the charge controller sees 40amp output for a very short time if at all. I’m still in the process of making changes and this wasn’t meant to be permanent but needed a quick solution for higher winter production. I plan to switch out the renogy rover 40 for a victron 250/100 by summer when the sun is higher in the sky.

 

[chrisski]

The panels will go 2-3 weeks with out anyone there to clean the panels so that probably takes another 10% off.

I’d be interested to find how much cleaning them actually helps.

I live in sunny dusty AZ, and for my RV panels I have leaned then at times they are delivering as much power as they can, and when I’m done cleaning them I see no difference before cleaning and after cleaning. Four months between rains sometimes.
After noticing this, I only plan on cleaning once or twice a year.

I think it would be a really dusty environment where cleaning actually helps to clean these.

 

[SoakedUp]

I’d be interested to find how much cleaning them actually helps.

I live in sunny dusty AZ, and for my RV panels I have leaned then at times they are delivering as much power as they can, and when I’m done cleaning them I see no difference before cleaning and after cleaning. Four months between rains sometimes.
After noticing this, I only plan on cleaning once or twice a year.

I think it would be a really dusty environment where cleaning actually helps to clean these.

My property is next to one of southern Californias largest OHV parks. The dust that gets kicked up every weekend by all the SxS, trucks, dirt bikes, and other off roaders can be intense. If it wasn’t for that the dust wouldn’t be too bad. I’ve seen a 100-200 watt increase in solar production after cleaning my panels after a couple busy holiday weekends in the desert.

 

[kenfused]

The only effective solution I found for this is a second SCC. One for the Renogy and one for the Stion. In my head math says for a 12 volt system, a 40 amp controller may allow 3 to 4 panels on a 12 volt system or twice that on a 24 volt system.

In my signature block there is a “mismatched panel” link that has some math that will let you calculate some scenarios.

On a different forum, someone had a build done by an inexperienced contractor, and among the mistakes the contractor made was putting a 100 watt “helper” panel with a 300 watt panel. Once the 100 watt panel was removed power output went up significantly. The math in the link will explain why.

Thanks for the link.very informative. Why on the mixed panel Scenario at the bottom, mixing 2 MPPT and a PWM SCC? why not use 3 MPPT?
Mainly to save on cost between the two SCC if you have 2 "junky" panels that you just want to find a way to use?

 

[chrisski]

Thanks for the link.very informative. Why on the mixed panel Scenario at the bottom, mixing 2 MPPT and a PWM SCC? why not use 3 MPPT?
Mainly to save on cost between the two SCC if you have 2 "junky" panels that you just want to find a way to use?

I use three MPPT SCCs on my setup. Others with multiple SCCs use mixed MPPTs and a PWM.