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In smartsolar datasheet it is written :
maximum battery current = 20 A
doest it mean that current to charge batteries will be properly limited to 20A or will it be a problem if, for instance, 400W are provided to victron and then : 400/12 => I = 33A. Will battery charge current be limited to 20A ? or will it break the victron ?
best regards
@iostrym Use the calculator https://mppt.victronenergy.com/.
You will find a 400W panel at 12v is more than 30% oversized for the charge controller and not generally advised. It would be better on a 24V system.
Yes it will current limit to 20A output. Whenever you configure a system you do not want to exceed the input Voltage of the charge controller, which in your case is 100V.
I have used a 390W Jinko panel as an example since I know their Specs.
You would still need to program your battery specific into the charge controller to make sure it is charged correctly according to manufacture recommendations.
Hi @iostrym
As written in the datasheet:
and in the manual:
The maximum (short circuit or Isc Panel) input Current of the panels is 20A for your controller, so as long as your panels are wired not to exceed that, there is no problem.
But will it be a lot of power dissipation by joule effect (temperature increase) if the charge controller can't distribute all energy provided by solar panel to batteries ?
350wc+185wc = 535WC (Isc < 20A, ok)
but because of 20A limitation on battery side, power provided to batteries is 20*14 = 280W
=> 535W-280W = 255W wasted and dissipated in joule effect.
I'm ok with the waste (because my concern is to increase production in winter or when there is no much sun) but I worry about the temperature rise of the victron controler. Will it damage it ? or is it designed to support this king of power dissipation ?
Hi @iostrym
There is no extra power dissipated, it is just not used. Just like when your battery is fully charged, no power will be taken from the panels.
(except when you use the power at the same time, but you get the idea)
do you mean that charge controller will detect that intensity is near 20A on battery side and then charge controller will modify panel voltage so that input power provided by panels will be decreased so that intensity will be never above 20A ?
it sounds me a little bit complicated this way, and there is a risk for the charge controller not to be "quick enough" (in case of sun quickly appear after a long cloudy day, etc...)
if not this way, then I don't get the point, 535W on pannel side provided to charge controller, only 280W provided to batteries (not to exceed 20A on batteries side). Where is the difference ?
And you are right, when batteries are charged and that only a few Amp are sent by charge controller to batteries, power on batterie side is even lower ! Energy should be "sent" somewhere else...
The energy is not 'sent somewhere else' it is just not 'taken from the solar panels'.
If you have a panel that is not connected, the energy is also not used, that's the same.
The MPPT is able to adjust how much power the solar panel produces by adjusting the panel's voltage. It will set the panel voltage to the optimal point for how much power the system needs.
For a 20A MPPT, if the panel can potentially produce more, the MPPT will limit how much that panel produces to keep to the 20A battery current limit. You will not damage the controller by connecting more power than the MPPT can use.
In fact it is recommended to install more, so you can get more power during cloudy weather.
now, I understand better working of your charge controllers. One last question :
are you sure that charge controller will modify voltage of solar panel to reach another "working point" (that seems complex to me because max power algorithm take several seconds if I correctly remember)
or maybe, like PWM controllers, when battery is charged or when 20A are almost reached, the controllers with shut on/off quickly solar pannels (alternance of Vmp, 0v, Vmp, 0v, Vmp, 0v) so that power provided by pannels with decrease but without "perturbing" Vmp calculation. (this second option is compatible with your sentence : "The MPPT is able to adjust how much power the solar panel produces by adjusting the panel's voltage" but not compatible with the other one : "It will set the panel voltage to the optimal point for how much power the system needs."
Best regards
Yes, as long as max Isc of the connected PV is below 20A and max voltage below 100V you don't have to worry.
