Is my Victron charge controller the correct size?

[TJD]

Greetings from Arizona.

We took delivery of our 2022 5.0 in September of last year. Our configuration included two 190W roof-top solar panels and a Zamp plug for an external panel. The trailer came equipped with the Victron Smartsolar MPPT 100 | 20 charge controller.

I watched the Victron video on charge controllers (https://youtu.be/Di499j08IeY) to understand what the numbers 100 and 20 designated in the product model name (MPPT 100 | 20). If I interpreted the video correctly, "100" designates the open circuit voltage maximum of the solar array. My panel specs show that they have open circuit voltage ratings of 24.09 volts. So there is plenty of 'room' to add a third, external panel without exceeding this maximum.

The second number, the "20," designates the array Short Circuit Current maximum. The specs I have for my 190W panels designate that this value is 9.98A per panel. So, the two roof-top panels put me just a hair below the maximum of 20A, before I have plugged in a third, external panel.


QUESTIONS FOR THE EXPERTS:

1. Have I incorrectly interpreted something in the Victron information?

2. Should I be concerned about this apparent mis-match of the charge controller? And if Escape installed too 'small' of a controller, how about the AWG 10 wire they used from the panels to the controller and from the controller to the batteries? Are these adequate to meet specifications for the 3-panel solar system?

3. Should not Escape have had the necessary expertise to foresee the need for an MPPT 100 | 30 to accommodate the external solar panel that the Zamp plug they installed was intended to power?

Thank you in advance for the help.

Tim Dennehy
Tucson Arizona
2022 Escape 5.0 TA
2 x 100AH batteries
2 x 190W solar panels + external panel (TBD)

 

[Selkirk]

It's my understanding that when ETI transitioned from the GoPower to Victron charge controllers in 2022, they initially started by supplying the 100|20....then later transitioned to the 100|30.

According to Victron's spec sheet, the 100|20 can accept a maximum of 580w PV input power when 24V panels are used.

https://www.victronenergy.com/uploa...-MPPT-75-10,-75-15,-100-15,-100-20_48V-EN.pdf

If I'm interpreting these specification correctly, it means the 100|20 should be capable of handling the maximum possible input power supplied by the two 190w fixed roof panels and up to an additional 200w of portable panels connected through the Zamp port.

 

[Centex]

Just FYI, Victron has a very nifty calculator for determining what controller you need for whatever PV array you have (it accepts input of specs for your panels and your array configuration). It also provides estimated performance data.

The Excel download version is here
https://www.victronenergy.com/upload/software/VE-MPPT-Calc-4_0.xlsm

The online version is here
https://www.victronenergy.com/mppt-calculator

 

[GinoandLinda]

If I'm interpreting these specification correctly, it means the 100|20 should be capable of handling the maximum possible input power supplied by the two 190w fixed roof panels and up to an additional 200w of portable panels connected through the Zamp port.

That is my understanding as well, or at least that's the explanation I got during pre-delivery at ETI, and I have the exact same setup with Victron MPPT 100/20.

 

[beebobby]

Make sure your zport is wired through the MPPT and not straight to the batteries (like my 2022 21C) when doing your calculations.

 

[Effie]

This controller is on the small size for your panels, my recommendation is to go with the Smart 100/30, it can deliver up to 440w. This will also work with an additional external panel.
The naming convention used by the industry is a bit confusing. Looking at the 100/20 model, the first number (100) refers to the total panel(s) input voltage allowed for this controller, 100 volts in this case, connecting higher voltage from a single or multiple panels in series will damage the controller. The second number (20) refers to the maximum output the controller can deliver, not the current coming from the panel(s). The controller will not be damaged by panel(s) capable of higher current, it will just deliver the maximum (20 amps in this case).
To simplify I’m assuming a 12v system. The 100/20 will work with your panels but it can deliver a maximum of 290w, your two roof panels can generate 380w together, this create an “over paneling” situation, your system will work but will deliver a maximum of 290w even when your panels can generate more. Some over paneling of 10-20% is fine but in your case it’s over 30%.

 

[BobG-ESC]

It's my understanding that when ETI transitioned from the GoPower to Victron charge controllers in 2022, they initially started by supplying the 100|20....then later transitioned to the 100|30.

According to Victron's spec sheet, the 100|20 can accept a maximum of 580w PV input power when 24V panels are used.

I think the author's system voltage is 12 volts, not 24 volts. If the charge controller is 100|20 then it can deliver 20 amps to the batteries. Voltage doesn't matter, it can only deliver 20 amps. So, if the author has a 12 volt battery system then he may not get the full potential from 2 x 190 watt panels. If he has a 24 volt battery then he can get the full potential.

If the roof top panels are connected to the controller in parallel then make sure the panel connected to the exterior plug is the same Voc or very close to the same as the roof top panels because the panels will all operate near the lower panel's voltage.

If the roof top panels are connected to the controller in series and the exterior panel connection is connected to the controller in parallel with the the rooftop series panels then make sure the exterior panel is double the roof top panel's Voc. If not then use a separate controller for the exterior plug.

In all cases make sure the controller is sized appropriately, i.e. it can handle the Voc and it can deliver the sum of the panel watts. I would add a separate controller for the exterior plug panel.

 

[GinoandLinda]

Just FYI, Victron has a very nifty calculator for determining what controller you need for whatever PV array you have (it accepts input of specs for your panels and your array configuration). It also provides estimated performance data.

The Excel download version is here
https://www.victronenergy.com/upload/software/VE-MPPT-Calc-4_0.xlsm

The online version is here
https://www.victronenergy.com/mppt-calculator

Thanks for that link, Centex. Looks like my setup, 2@190watt + 130watt portable, is well within spec for the 100/20 MPPT. Also, reading some of the comments and questions on the Victron site, it appears the 100/20 has more features than the 100/30.

 

[BobG-ESC]

Thanks for that link, Centex. Looks like my setup, 2@190watt + 130watt portable, is well within spec for the 100/20 MPPT. Also, reading some of the comments and questions on the Victron site, it appears the 100/20 has more features than the 100/30.

2x190W = 380W
380Wx0.9=342W
342W/12V=28Amps

28Amps is more than the 20 amp limit of the Charge Controller. Even using 13.6V = 25 amps is more than the 20 amp limit.

However, if you connect the 130 watt portable to the controller in parallel with the 2x 190 watt panels then they will all work at the lower voltage of arround 19 or 20 volts of the 130 watt panel instead of 24.9 volts which yields about 20% less wattage from the 190 watt panels. The result is that the 130 watt panel will gain you around 50 watts.


Remember, the 20 amp limit for the SCC is the output amps. It is not the solar panel amps.

 

[GinoandLinda]

2x190W = 380W
380Wx0.9=342W
342W/12V=28Amps

28Amps is more than the 20 amp limit of the Charge Controller. Even using 13.6V = 25 amps is more than the 20 amp limit.

However, if you connect the 130 watt portable to the controller in parallel with the 2x 190 watt panels then they will all work at the lower voltage of arround 19 or 20 volts of the 130 watt panel instead of 24.9 volts which yields about 20% less wattage from the 190 watt panels. The result is that the 130 watt panel will gain you around 50 watts.


Remember, the 20 amp limit for the SCC is the output amps. It is not the solar panel amps.

Thanks. That is helpful. Am I correct in that the above assumes my panels are able to achieve 100% performance which is not normally the case. On our last trip, the 5.0 was parked north/south next to a tree in partial shade. I had the 130watt portable in full sun. With that, the batteries were still able to fully charge through the course of the day. Even if, by some miracle, all three panels reach 100% performance, the Victron 100/20 MPPT will still manage the charging of the batteries. Is that a correct?

 

[TJD]

Thanks so much for the response.
My roof-top panels are 12 volt, wired in parallel. I should have provided these details in my original message. So, as detailed in the Victron link you provided, the Nominal PV Power for 12 volt panels is 290 W, much less than the potential output of my two 190W panels. As pointed out by other responders, below, this is not only an inefficient use of the two 190W roof-top panels but it also makes the use of an accessory panel very questionable, to put it mildly.
Lastly, I am still getting hung up on the issue, raised in the Victron tutorial video, of Maximum PV short circuit current. The table you linked is consistent with the video information on this point. That is, the maximum short circuit current is 20A. Footnote 2 of the table reiterates the point: "A PV array with a higher short circuit current may damage the controller." As I noted previously, my roof-top panels (GoPower Solar GP-PV-190M) have short circuit current values of 9.98A each. Plugging in the accessory panel will exceed this specified limit significantly.

I would be grateful to have any errors in my thinking pointed out. But at this point it appears that the consensus opinion is that Escape should have installed an MPPT 100|30 to meet Victron specification.

Thanks again for the help.

--Tim Dennehy

 

[TJD]

Thanks for the response CENTEX. The calculator was helpful and a useful heuristic for teaching me a little about electronics. The calculator yielded a consistent recommendation for the MPPT 100|30 controller. Your help is greatly appreciated.

 

[BobG-ESC]

Thanks. That is helpful. Am I correct in that the above assumes my panels are able to achieve 100% ....

Using 90% (0.9) in the calculations I calculated the 2x 190 watt panels are able to put out 342 watts.

The solar charge controller 100|20 can put out 20amps. At 12 volts (13.6 volts), that is 272 watts. If your batteries are set up in series then they would be 24 volts (27.2 volts) and then the SCC could put out 27.2V x 20 amps = 544 watts.

I do not know whether you are running your batteries in series or parallel. I run mine in series. I assume you run yours in parallel. If you do then your SCC is undersized for the 2 x 190 watt panels.

Assuming you are a 12 volt system, what I would do is run the 130 watt panel on the 100|20 SCC and I would buy a 100|30 SCC for the 2 x 190 watt panels. I might also run the 2x 190 watt panels in series instead of parallel but it doesn't really matter. They would be a little more efficient at the higher voltage of running them in series. It will also give you a little more output in the morning and evening.

Do you also have a Victron smart shunt? If so then you can use Victron Connect app to keep track of the battery State of Charge (SOC) and you can monitor the solar input as well as loads. You will also be able to keep track of the ouput of each Victron SCC. If you don't have a Victron shunt, I suggest you install one. It will help you manage your batteries. Also put Victron Connect app on your phone.

 

[Selkirk]

My roof-top panels are 12 volt, wired in parallel.

Are you certain that the GoPower Solar GP-PV-190M panels supplied by ETI are 12v and not 24v?

 

[TJD]

Thanks SageRpod. I would love to be able to accept the conclusion that the Victron MPPT 100|20 would do the job. It's just that all the investigations I have done have indicated that it would be significantly out of Victron specifications with the addition of a third, external panel.
I was prompted to look into this question by the many warnings in this Forum about carefully matching the external panel to the roof-top panels.
I have very limited confidence in my electrical knowledge so I appreciate having errors in my thinking pointed out.
Thanks again for your time and input.
--Tim Dennehy

 

[TJD]

Thanks BobG.
I really appreciate the help.
Your assumption was correct, Escape wired the panels in parallel.
I may well end up doing as you suggest and purchasing a Victron MPPT 100|30 controller, using it for the two roof-top panels, and then using the existing MPPT 100|20 for the external panel.
It is a little annoying that I have just completed the re-wiring of the Zamp plug as recommended by Escape; moving it from direct connection to the battery to the Victron controller. Of course, this was all done under the false assumption that Escape had installed a controller that was sufficient to handle the solar panel that I would plug into the Zamp plug that they installed.
I had hoped that the $50,000 we paid Escape would free me of having to do this kind of work....
And yes, I have the Victron shunt and battery monitor. The phone app is nifty.
Thanks again,
--Tim Dennehy

 

[BobG-ESC]

Lastly, I am still getting hung up on the issue, raised in the Victron tutorial video, of Maximum PV short circuit current. The table you linked is consistent with the video information on this point. That is, the maximum short circuit current is 20A. Footnote 2 of the table reiterates the point: "A PV array with a higher short circuit current may damage the controller." As I noted previously, my roof-top panels (GoPower Solar GP-PV-190M) have short circuit current values of 9.98A each. Plugging in the accessory panel will exceed this specified limit significantly.
--Tim Dennehy

Watch and listen carefully to the video. The 20 in the "100|20" is the maximum output amperage of the controller. I don't know the different voltages the SCC can operate at but it will sense the battery voltage and then operate at that voltage. It can at least operate at 12 or 24 volts. Maybe 36 or 48 volts too. I don't know. It can handle the input amps from the solar array. I don't know what the max amps would be but am sure it can handle any solar array that is within its watt rating.

It is important that you have a disconnect switch between the solar panels and the SCC. The SCC needs to be connected to the battery so it can sense the system voltage before the solar panels come on line. It is not easy to find a switch that can operate at the high DC voltage of the solar panels. I only switch the positive conductor from the solar panels because the trailer is plastic and if there is a problem with the positive conductor shorting there is nothing for it to complete a short circuit. You can use a switch/circuit breaker that can handle the DC voltage instead of a switch. That is what I had to do.

 

[GinoandLinda]

I’m new to this solar thing, so this thread has been really helpful. Thanks all. I need to get educated on this stuff.

 

[TJD]

Hi Again Selkirk,
I could not divine the answer to this simple question from the Go Power GP-PV-190M spec sheet (linked below). So I searched the internet and found multiple sites claiming that most 12 volt panels usually have 36 cells. My panels have 36 cells.
Next I used the Go Power specs to solve the W=AxV equation. 190W/9.45 maximum current = 20.1 volts. 12 volt panels are supposed to generate 18-20 volts.
I would be pleased to be wrong....
Thanks again,
--Tim Dennehy
https://s3-us-west-2.amazonaws.com/catsy.549/SPEC_GP-PV-190M.pdf

 

[TJD]

Thanks,
Will go back and listen to the Victron video again.
I installed the solar cut-off switch yesterday (on + wire), following a wiring diagram and switch hardware suggested by Victron.
And I agree with SageRpod. You folks are great for taking the time to help with this forum.
--Tim