Is my Victron charge controller the correct size?

[Centex]

Originally Posted by BobG

Watch and listen carefully to the video. The 20 in the "100|20" is the ouput amperage of the controller.

While correct that the "20" in the model number refers to the max rated output current, please note that in the case of the specific controller referenced by the OP Victron also stipulates that the max input should be limited to 20A at any voltage within its spec range lest the controller be damaged.

Originally Posted by BobG

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.

Again, reference to the Victron specs for the controller in question reveal it is rated for 12 / 24 / 48 volts nominal input.
___________

IMO one benefit of using the Victron calculator linked above is that rather than just relying on nominal expressions of watts and voltage describing a PV panel, it accepts input of the complete set of industry standard parameters which describe a panel's performance in detail:

V mpp
I mpp
V oc
I sc
V temp coeff
I temp coeff

All of those parameter values are found on the GoPower website for the OPs referenced panel.

IF one takes the time to input that full set of data to describe their panel(s) in the calculator, and uses the calculator's facility to describe how those panels are connected in the array (series, parallel, or a combination of series / parallel) the resulting information regarding charging performance with a given Victron brand MPPT controller is quite accurate and valid (good data in = good data out).

Just for consideration, Have Fun!

[BobG]

Originally Posted by Selkirk

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

The panel's Voc is 24.9 volts. If connected in parallel, that is not enough voltage to start a Victron MPPT SCC 100|20 at 32+ volts that is necessary for a 24 volt system. If the panels were connected in series to the SCC then there would be enough volts. The voltage needs to be at least 5 volts above the system voltage to start the Victron MPPT SCC.

If the panels are connected in parallel or series then they can operate the Victron MPPT SCC 100|20 if the system voltage (batteries) are 12 volt.

[BobG]

Originally Posted by Centex

While correct that the "20" in the model number refers to the max rated output current, please note that in the case of the specific controller referenced by the OP VIctron also stipulates that the max input should be limited to 20A at any voltage within its spec range lest the controller be damaged.
Again, reference to the Victron specs for the controller in question reveal it is rated for 12 / 24 / 48 volts nominal input.

I looked in the manual I have and did not find the maximum input amperage. Which page is it on. I have one of those in my 21NE. I knew it had to be somewhere but couldn't find it. Thanks, Bob

[TJD]

Thanks BobG,
Very helpful observation. I watched the video again and, indeed, I misunderstood the information on array short circuit. This value needs to be under 60, which it will be with my desired 3-panel setup.
So this leaves me with only one problem--as you pointed out, the 20A output of the MPPT 100|20 controller is inefficient for capturing maximum benefit from two 190W panels. Thus, it is ridiculous to add a third external panel to this controller.
Thanks so much,
--Tim Dennehy

[Centex]

Originally Posted by BobG

I looked in the manual I have and did not find the maximum input amperage. Which page is it on. I have one of those in my 21NE. I knew it had to be somewhere but couldn't find it. Thanks, Bob

I refer to the manual at this link

https://www.victronenergy.com/upload...ual-pdf-en.pdf

Looking at the technical specifications on page 63:
Max. PV short circuit current [superscript "2"] = 20A for the MPPT 100/20

On the following page we find footnote 2:
2) A higher short circuit current may damage the solar charger in case of reverse polarity connection of the PV array.

[SRS]

Originally Posted by 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

Like you my trailer came with the zamp port wired to the batteries. And since ETI recommends an external panel without a controller, that's what I got. After asking some questions here it was suggested I read the below article on using mismatched solar panels.

https://www.explorist.life/using-mis...r-panel-sizes/

So, I rewired the zamp to the controller and did an experiment. I covered my 190w roof solar with a tarp to simulate the roof solar in shade and connected the portable 100w panel through the zamp port. While I got some charging, it was very small. Next I wired the zamp port back to the battery, got an inexpensive Renogy PWM controller and wired it into the portable panel and with the roof solar covered I plugged the portable into the zamp port. The result was much higher output from the solar suitcase. Since I got the portable to supplement the roof solar when in shade, this seems to be the best setup. So, you could get the 100/30 for your roof solar and use the 100/20 for you portable. Unfortunately that means rewiring the zamp port back to the battery like it was delivered. As stated previously, a solar disconnect switch is really useful, see the video below for one option and the one I installed. I also installed a disconnect on the positive wire going into the controller from the battery. When solar is disconnected from the Victron controller, it's a good idea to also disconnect the battery. Some may feel this is overkill but when it comes to electricity I'll go with overkill-but that's just me. The two disconnects make it easy to work on the electrical system because it's a pain covering the roof panel with a tarp or plywood.

https://www.youtube.com/watch?v=HOXnWXvLXko&t=34s

[Perry Butler]

I'm late to the party, as you've already figured out, your Victron 100/30 is too small for two 190 watt panels and a "external" panel. Period!

So wire your "external" panel/Zamp port to your Victron 100/20 with the needed fusing and solar disconnect. For the 380 watts on your roof, install a Victron 100/30 SCC, again with needed fusing and solar disconnect. Do this and you'll be golden.

We had 463 watts on the roof of our 5.0, the ETI supplied 170 watt GoPower panel and three 100 watt Renogy panels wired in parallel (7 watt loss from the minor VMP difference). We had all the watts we needed at that time and left our 100 watt Renogy portable at home.

_________________________________________

Did I get this correct, but Escape has wired the Zamp port directly to the batteries ass u me ing you will know you have to have a portable with it's own controller? Good electrical practice is to always have the Zamp port wired to a solar controller in the camper. It is more efficient to have the 18-22 volts of the portable going through you wires than 13-14 volts, since most only use 10 awg wire from the portable to the camper.

Food for thought,

Perry

[NEWYORKHILLBILLY]

Originally Posted by TJD

Thanks BobG,
Very helpful observation. I watched the video again and, indeed, I misunderstood the information on array short circuit. This value needs to be under 60, which it will be with my desired 3-panel setup.
So this leaves me with only one problem--as you pointed out, the 20A output of the MPPT 100|20 controller is inefficient for capturing maximum benefit from two 190W panels. Thus, it is ridiculous to add a third external panel to this controller.
Thanks so much,
--Tim Dennehy

The rated output current go power 190 watt panels is.9.45 A
9.45x2 =18.9 amps. It looks like 20-amp controller is just big enough for roof panels. any portable panel would likely put you over. One thing to remember is on the roof top panel it's unlikely that they will ever produce the full output being flat mounted. I have both panels on my roof and have never seen the full output. I put in a Victron 100/50-amp controller to Handel any future expansion or portable panels. I think if you want to add a portable panel. You have two choices.
1. use a portable with its own controller(may have to rewire you zamp port)
2. upgrade your current 20-amp controller to 30 or 50 amp

[HBGH]

Originally Posted by NEWYORKHILLBILLY

The rated output current go power 190 watt panels is.9.45 A
9.45x2 =18.9 amps. It looks like 20-amp controller is just big enough for roof panels. any portable panel would likely put you over. One thing to remember is on the roof top panel it's unlikely that they will ever produce the full output being flat mounted. I have both panels on my roof and have never seen the full output. I put in a Victron 100/50-amp controller to Handel any future expansion or portable panels. I think if you want to add a portable panel. You have two choices.
1. use a portable with its own controller(may have to rewire you zamp port)
2. upgrade your current 20-amp controller to 30 or 50 amp

Hello, a new poster here. My wife and I took delivery of an Escape 19 in early January of this year after having owned, over the years, a tent trailer, a self-built tear-drop and a Scamp 13.
I find the original poster's question and the other posters' comments timely as I am currently undertaking the same analysis for our camper as I would like to integrate a 100W panel from an unrelated solar project into the Escape's power supply.
Before my comments, I note here that I am not an electrician but have relied on the National Electrical Code (NEC) for guidance in the past when undertaking an electricity-related project. The NEC includes Article 690 which addresses Solar Voltaic (PV) Systems.
For my purposes, in the absence of information to the contrary, I consider my Escape's PV system to a be "Stand-alone system" under that Article and governed by the Article's text.
Per my understanding of that text, your computation of your panels' current is correct to a point - 9.45 amps X 2 = 18.9 amps. However my reading of the code suggests that the maximum current should be determined as: module short circuit current X modules in parallel X 1.25 (safety factor)= maximum circuit current (9.45X2X1.25 = 23.63 amps). Thus the 20 amp Victron controller is insufficient for what I understand the original poster (and I) want to do. I agree the most straight-forward approach is to install a 30 amp or larger controller. I think it was an oversight on my part to have not specified a higher amperage charge controller on our build sheet.

On a related issue, again referring to the NEC article 690, I think Escape was remiss in not including a PV system (panel) disconnect and an energy storage system (battery) disconnect in the PV system build. These disconnects make working on a system so much easier. In my self-built PV systems I've used appropriately rated DC circuit breakers in the positive conductor for over-current protection and as component disconnects. My plan is to install these disconnects/breakers when I install a 30 amp controller once the weather here eases a bit.

I appreciate all the thoughtful comments on this forum and look forward to reading more in the future.

[NEWYORKHILLBILLY]

Originally Posted by HBGH

Hello, a new poster here. My wife and I took delivery of an Escape 19 in early January of this year after having owned, over the years, a tent trailer, a self-built tear-drop and a Scamp 13.
I find the original poster's question and the other posters' comments timely as I am currently undertaking the same analysis for our camper as I would like to integrate a 100W panel from an unrelated solar project into the Escape's power supply.
Before my comments, I note here that I am not an electrician but have relied on the National Electrical Code (NEC) for guidance in the past when undertaking an electricity-related project. The NEC includes Article 690 which addresses Solar Voltaic (PV) Systems.
For my purposes, in the absence of information to the contrary, I consider my Escape's PV system to a be "Stand-alone system" under that Article and governed by the Article's text.
Per my understanding of that text, your computation of your panels' current is correct to a point - 9.45 amps X 2 = 18.9 amps. However my reading of the code suggests that the maximum current should be determined as: module short circuit current X modules in parallel X 1.25 (safety factor)= maximum circuit current (9.45X2X1.25 = 23.63 amps). Thus the 20 amp Victron controller is insufficient for what I understand the original poster (and I) want to do. I agree the most straight-forward approach is to install a 30 amp or larger controller. I think it was an oversight on my part to have not specified a higher amperage charge controller on our build sheet.

On a related issue, again referring to the NEC article 690, I think Escape was remiss in not including a PV system (panel) disconnect and an energy storage system (battery) disconnect in the PV system build. These disconnects make working on a system so much easier. In my self-built PV systems I've used appropriately rated DC circuit breakers in the positive conductor for over-current protection and as component disconnects. My plan is to install these disconnects/breakers when I install a 30 amp controller once the weather here eases a bit.

I appreciate all the thoughtful comments on this forum and look forward to reading more in the future.

To my knowledge there is nothing in the NEC code that cover 12-volt Rv solar systems . These home systems are connected to the grid and may need actional safety features.
am solor https://amsolar.com/diy-rv-solar-ins...lectrical-code
one thing to keep in mind is the solar ETI install is 12-volt panels. Any reverence in the NEC code is for 30volt or above systems for homes and buildings.
If your more comfortable adding a 25% safety factor. go for it. But the go pro panels have a short circuit current of 9.98 x 2 =19.96 amps. maybe I am missing something. I don't see any way that these panels could ever produce more than 19.96 amps. except for lighting in which case 25% safety factor would also be toast.
https://gopowersolar.com/products/hi...-solar-module/

[beebobby]

2022 21C single roof panel. zport wired to batteries. Renogy 100w suitcase w/controller. I think I'm going to leave both systems as is. I have a small 12v trolling motor batt for a canoe that I could charge (and have) from the portable. Could also be used for more 12v charging applications. It was so easy with the Casita.

[BobG]

Originally Posted by Centex

On the following page we find footnote 2:
2) A higher short circuit current may damage the solar charger in case of reverse polarity connection of the PV array.

Isn't this the maximum amperage that the MPPT can deal with if the panels are accidentally connected reverse polarity? Like might happen when using zamp equipment.

It is my understanding that you can over panel Victron charge controllers and the controller will clip the amperage. I don't think that I would do that because it seems wasteful.

[Centex]

Originally Posted by BobG

Isn't this the maximum amperage that the MPPT can deal with if the panels are accidentally connected reverse polarity? Like might happen when using zamp equipment.

It is my understanding that you can over panel Victron charge controllers and the controller will clip the amperage. I don't think that I would do that because it seems wasteful.

I think you've answered your own question; IMO the specification for "Max. PV short circuit current" is provided because

• Exceeding that specification yields no performance benefit
• Exceeding that specification surpasses the unit's ability to provide the "PV reverse polarity protection and PV reverse current protection" touted in the manual at 3.4. Extensive electronic protection (page 4)

Maybe worth noting that in 3.4. Extensive electronic protection there's no mention of over-current protection in general (?). I have no idea what happens when the power source into a controller is capable of delivering, and the load on the output side demands, current in excess of the controller's current rating (have no interest in 'testing' that any more than I would want to 'test' exceeding a controller's I/O voltage ratings).

Maybe you're right, maybe the controller 'clips' ('sheds'?) the excess current in some manner (?). I don't know how that would be accomplished but it strikes me that any device that 'clips / sheds' energy also invariably generates heat in that process, and unnecessary heat is generally to be avoided as an enemy of electronics longevity.

So, for all practical purposes, a controller's "Max. PV short circuit current" strikes me as a specification which should be known and respected when configuring a system. And isn't configuring a system what this thread is about?

[BobG]

Originally Posted by Centex

.......So, for all practical purposes, the controller's "Max. PV short circuit current" strikes me as a specification which should be known and respected when configuring a system. And isn't configuring a system what this thread is about?

You are correct. I misunderstood what you were pointing out and I certainly wasn't aware that there was protection against reverse connecting the panels. It is comforting to know there is some protection for miss wiring.

For someone who has been forewarned about this limitation, they can still over panel without damaging the controller if they think there is a good reason to do so and as long as they connect everything properly. I think the Victron sizing app over sizes by 30% as default. The user can change this if they do not want to oversize.

[TJD]

Wow, what a helpful collection of responses. Thanks to you all. --Tim

[CE Vogel]

Originally Posted by Centex

Maybe you're right, maybe the controller 'clips' ('sheds'?) the excess current in some manner (?). I don't know how that would be accomplished but it strikes me that any device that 'clips / sheds' energy also invariably generates heat in that process, and unnecessary heat is generally to be avoided as an enemy of electronics longevity.

A solar controller can manage moderately excessive input without damage. When operating normally, the current through the charge controller keeps the solar panel voltage below the panel's maximum voltage. Once the charge controller reaches its maximum current capacity, the solar panel voltage will rise as it is no longer fully loaded. As long as the charge controller is drawing enough current to keep the solar panel voltage below the charge controller's maximum input voltage rating, no damage will occur. Of course, the maximum power of the solar panels is not being utilized under these conditions.

[BobG]

Originally Posted by SRS

..... I rewired the zamp to the controller and did an experiment. I covered my 190w roof solar with a tarp to simulate the roof solar in shade and connected the portable 100w panel through the zamp port. While I got some charging, it was very small.

When two or more solar panels with different voltages (Voc) are connected in parallel to a solar charge controller the controller will accept amperage from all the panels but the voltage will be the voltage of the lowest voltage panel.

Could the reason you got very small charging be that the solar controller sensed the smaller voltage of the covered solar panels and therefore the portable 100w panel was operating at a very small voltage? Try the same thing but open the switch between the SCC and the roof top panels and see what happens. I bet your 100 amp portable panel will work just fine. The portable panel might have been heating up the covered roof top panels.

I have 6 panels on my roof 2 series arrays, each array connected to its own SCC. I did this so that when a portion of a panel or a full panel is shaded, the bypass diodes on that panel routes the current around the affected PV string(s). The voltage delivered to the SCC does not include the voltage from the bypassed string(s) but is still enough to operate the SCC. I used series because I think it is better at dealing with shade. The panels within each of my arrays are identical but the 2 arrays use different size panels, one is (2) 210 watt panels and the other is (4) 160 watt panels.

[SRS]

Originally Posted by BobG

When two or more solar panels with different voltages (Voc) are connected in parallel to a solar charge controller the controller will accept amperage from all the panels but the voltage will be the voltage of the lowest voltage panel.

Could the reason you got very small charging be that the solar controller sensed the smaller voltage of the covered solar panels and therefore the portable 100w panel was operating at a very small voltage? Try the same thing but open the switch between the SCC and the roof top panels and see what happens. I bet your 100 amp portable panel will work just fine. The portable panel might have been heating up the covered roof top panels.

I have 6 panels on my roof 2 series arrays, each array connected to its own SCC. I did this so that when a portion of a panel or a full panel is shaded, the bypass diodes on that panel routes the current around the affected PV string(s). The voltage delivered to the SCC does not include the voltage from the bypassed string(s) but is still enough to operate the SCC. I used series because I think it is better at dealing with shade. The panels within each of my arrays are identical but the 2 arrays use different size panels, one is (2) 210 watt panels and the other is (4) 160 watt panels.

I'm sure that is why. The lower voltage covered panel, sensed by the controller, limits the output of the 100W panel. You bring up a good point about opening up the roof solar breaker, which would eliminate the low voltage problem at the SCC.
Most of this solar stuff is new to me so I've been learning as I read posts here and from other resources that seem reliable. I didn't learn about adding a breaker until after I'd done the experiment. So, at this point I'm not going to go back. But for other folks It's a great idea. As fare as overheating the rooftop panel, I didn't have both connected long enough to do that.

[BobG]

Originally Posted by SRS

As fare as overheating the rooftop panel, I didn't have both connected long enough to do that.

If any heating took place I doubt it would be much. I think the bypass diodes would get involved. I'm not sure what they would do. Maybe they would function as blocking diodes without a problem.

One thing to remember, when using Victron SCC, the controller is built to operate at different voltages. Therefore it needs to sense the voltage of the battery so it knows what voltage to use before the panels are turned on. You need a switch between the SCC and panels. It does not need to be a breaker but if a switch, it should be rated for the DC voltage of the panel array connected to it. And, that is not so easy to find at a reasonable price. I wasn't able to find one.

[John in Santa Cruz]

I would NOT parallel panels of significantly different voltages... for instance my 350W panel is a 40V PV max / 36V PV load... paralleling that with the typical 20-16V '12V' panel would probably be very bad for the lower voltage panel. I also would not series panels of significantly different amperages.