Victron 100/50 SCC with 790 watts of panel

[Kcdaniels]

I'm A little confused...? Is there a way this will work or would I have to go to 24 volt setup as now I'm 12 volt ? I have two of these 395 watt panels..

Victron says max 700 watts for the 100/50

 

[HRTKD]

It will work fine. The Victron MPPT 100/50 will supply the voltage that your battery bank needs. I run two 320 watt panels in series into the same controller. You're a little over-paneled, but that's OK.

 

[Kcdaniels]

It will work fine. The Victron MPPT 100/50 will supply the voltage that your battery bank needs. I run two 320 watt panels in series into the same controller. You're a little over-paneled, but that's OK.

Thanks...thought I had it covered but then I read about max 700 watt and got a little nervous.?

 

[HRTKD]

700 watts is nominal, not max. The key specification to NEVER exceed is the Max PV Input Volts, which for that device is 100 volts.

 

[Kcdaniels]

700 watts is nominal, not max. The key specification to NEVER exceed is the Max PV Input Volts, which for that device is 100 volts.

So the two panels wired in series... Max PV volts would be 40.74 ? Or 81.48

 

[rmaddy]

With a Voc of 48.74V you can't safely put two of those panels in series with that charge controller. The combined Voc would be 97.48V. Voc goes up in the cold. If your panels ever got below about 70ºF you could fry the charge controller.

You have to put your two panels in parallel with that charge controller.

 

[HOU_Castle]

With a Voc of 48.74V you can't safely put two of those panels in series with that charge controller. The combined Voc would be 97.48V. Voc goes up in the cold. If your panels over got below about 70ºF you could fry the charge controller.

You have to put your two panels in parallel with that charge controller.

You need to monitor the total voltage (Voc) during the winter time, Voc can go up easily/immediately and damage your Victron. Victron will send the overvoltage warning. If the distance from panels to mppt is less than 25 ft, you can parallel the panels, assuming your cable is 12AWG.

 

[Kcdaniels]

You need to monitor the total voltage (Voc) during the winter time, Voc can go up easily/immediately and damage your Victron. Victron will send the overvoltage warning. If the distance from panels to mppt is less than 25 ft, you can parallel the panels, assuming your cable is 12AWG.

Yes less than 25' and cable is 10awg...so wire up in Parallel.....

 

[Rocketman]

I have 800w on my MotorHome with the Victron mppt 100/50. My panels are flat. Only a few times have I noticed the SCC putting out 700 watts (it’s max). For that to happen, I need - between 11am and 2pm in the summer a very bright day and the batteries still in bulk mode. Usually a great solar day will have the batteries pretty well full by that point. - so it does make sense to be over paneled.

 

[HOU_Castle]

what is the total panels Voc? Voc will spike during cooler months, such as winter season. I have seen a couple dead Victron mppts (100/30 and 100/50) due to overvoltage.

 

[Kcdaniels]

what is the total panels Voc? Voc will spike during cooler months, such as winter season. I have seen a couple dead Victron mppts (100/30 and 100/50) due to overvoltage.

Here are the panel specs

 

[rmaddy]

what is the total panels Voc? Voc will spike during cooler months, such as winter season. I have seen a couple dead Victron mppts (100/30 and 100/50) due to overvoltage.

You replied (#7) to my post (#6) covering the Voc and the cold. I'm confused why you then posted this question. Am I misunderstanding something here?

 

[ericfx1984]

Curious... What would happen if you hit this controller with almost 1000 watts on 12v?

 

[HRTKD]

Curious... What would happen if you hit this controller with almost 1000 watts on 12v?

As long as the PV volts didn't exceed the Max PV Input Voltage of the controller then it would simply provide the max output amps and no more.

 

[chrisski]

Curious... What would happen if you hit this controller with almost 1000 watts on 12v?

I don’t recommend that because that is over specs, but I do something similar on my crate build with a Victron 75/15 with success. I have seen 1 overamperage fault on the controller, and other than that, the SCC handles this by only pulling what is needed. The max PV short circuit current off the spec sheet is 15 amps, but the panels I use have 27.9 amps.

Max output is somewhere around 420 watts at charging volts of 27.6 and max production of 15 amps. I use 900 watts of panels to get this, set up 3 strings of 300 watts each. One to the East for morning sun, one to the west for evening sun, and one to the south for sun most of the time. I have a 24 volt 15 amp battery bank that I start a 220 watt load(8.3 amps) a couple hours before the panels start producing and this set up will get me to the end of the day and the batteries are fully charged.

If this were other than my portable generator, like my Rv build, or my house build, I would not overpanel by so much. When I first built this, my 15 amp BMS shut down a lot, but I added an additional battery for a total of two 15 amp BMSs and have not had a problem. For my crate build, I will fill a crockpot of food before work and after work its ready. I could not do that without the setup I have. To meet specs, the Victron SCC would need to be the 30 amp version.

 

[DJSmiley]

395W is the rated output, under optimal conditions. When installed flat (eg on a van) that's never archieved, so nothing to worry about.

Temperature might be an issue however. 48.74V x 2 = 97.48V, so within range. But that voltage is increased at lower temperatures and rated at 25 celcius.

I can't find the temp coefficient for these panels, but assuming 0.04%/C, -15 (5F) is 40x0,04% = 1.6% more voltage.. 97.48 + 1.6% = 99V...

Thats about as close as you can/would get... If gets any colder, you need to parallel the panels..

 

[rmaddy]

I can't find the temp coefficient for these panels, but assuming 0.04%/C, -15 (5F) is 40x0,04% = 1.6% more voltage.. 97.48 + 1.6% = 99V...

The temp coefficient would be more like -0.4%/ºC. You are off by a factor of 10. It would only take a 4ºC temp drop to get a 1.6% increase in Voc.

 

[DJSmiley]

whoopssss. you're right.. checked some panels and they are 0.25 - 0.35V at Voc
(Higher at Pmax, but that's lower than Voc so for these calculations doesn't matter)

0.04% is the tempcoefficient for the current.... Isc

So at -15 (5F) would result in 113V for these panels (assuming 0.4%/C), thus toasting your controller when the panels are in series.

 

[Tobi17]

So at -15 (5F) would result in 113V for these panels (assuming 0.4%/C), thus toasting your controller when the panels are in series.

Will the mppt really be toasted with 113V peak? I know that the 100/50 (I have one) controller is limited to 100V, BUT inside the mosfets are rated to a maximum of 160V. I cannot imagine the mppt is start burning at 105V if it is rated to 100V. Maybe, there are other components beside the mosfets which are toasted directly above 100V, however I do think every electronical component has a tolerance range. Me personally, cannot imagine the limits are that exact on +/- 1V. If you want to put 1400W (24V) on the mppt 100/50, it is obvious that you need to push it to the limits.

However, surely I do understand the limits. I do not want to run my mppt beyond the limits, but it must be acceptable to run the mppt at its limits (100/50). Additionally, for this mppt on overpanelling you need to ensure the lsc is not exceeding 60A. Maybe, some people with toasted mppt can share their experiences, this would be great!

In General, I think the most dangerous issue on these mppt controller ist, that the mostfets failed and on fail the short the circuit. This would result in 100V are directly send to the battery. Interesting thing