Can I connect a 340 watt panel to my 75/15 smart mppt controller
asked
will I be able to conect a 340 watt panel to my 75/15 smart mppt charge controller 12 volt system
Yes, as long as you're panel is NOT exceeding the 15A short current (Isc on the panels datasheet).
However, the charge controller will limit to approx 180W, so any excess solar if available is left unused... So apart from more output during winter and parts of spring/autumn it doesn't make really sense to install such a nice panel on a small controller.
Data sheet says 220w for the 75/15 though... Sorta splitting hairs at this point.
Also, that panel will not come close to exceeding 15a imp, unless it is some sort of super panel that can somehow can output 150% beyond it's rated power.... The 15a number on the MPPT is representative of the maximum amps that it can output to the batteries btw.
To give you an idea what the 75/15 means.
The 75 stands for the maximum allowed open terminal voltage (Voc) of your solar panel. Of course there could be more. This voltage must certainly not be exceeded. The 15 means with how many amps the solar charger can charge your battery. If you are unsure about your solar panel, first check the open terminal voltage of your solar panel to ensure that it is not exceeded.
Just curious... What is the use case of this MPPT? What kind of panel would be 75v? And if such a panel existed, it would probably be in the 700w+ range, way more than the 440w this MPPT could handle on a 24v system. Running 2 of these hulk panels in series would double that insane amount of watts, and very likely go beyond the MPPTs 75voc max.
Multiple small panels in series, high-voltage panels, rather easy to get 70V+ but at low currents so the 15A is still sufficient.
I thought of a bunch of panels in series, but I didnt know what that use case would be. Robotics or something?
a 75/15 would be undersized based on the 340 watt panel. That's OK but the maximum output of the solar system will be limited by the controller, not the panel: on a 12 volt system, a 75/15 will net you 12 x 15 = 180 watts maximum.
A closer match to your panel would be a 100/30. The solar output would then be limited by the panel not the max power possible from the controller (12 x 30 = 360 watts). Note that you almost never get the power output specified for any solar panel. This power is a best case number with the sun angle and other conditions at their optimum.
The MPPT's maximum voltage must not be exceeded under any circumstances. Note that open circuit voltage of the panel goes UP as the temperature goes down so it's open circuit voltage at the lowest temperature you will ever see must be less than the spec for the specific MPPT model you use. You should check this for your panel and calculate the low temperature open circuit voltage. If you series connect more panels, then the open circuit voltage presented to the controller will be the sum of all panels and that must be under the max voltage spec.
The panel voltage can be less. The minimum is 5 volts higher than your battery voltage so 17 volts for a 12 volt battery.
FYI: The datasheet says 220watt, which means it can output 15 amps @ 14.6v. You can't properly charge a 12v battery at 12.0v volts, so the "180w" figure is incorrect...
(correct me if Im wrong?)
With an MPPT solar charge controller, panel voltage and current are independent of the battery voltage. The controller locates the maximum power point (voltage vs current) of the PANEL and transforms that to charging current for the battery. The panel specs should include the open circuit voltage, the short current current and the maximum power transfer point (voltage and current).
(A PWM solar charge controller performs best when the panel voltage is close to (but larger than) the battery voltage. It rapidly turns on and off the connection between panel and battery to control the charging current. Any additional panel voltage wastes power.)
The simple Answer is NO.
The datasheet say clearly 200W @12V and 400W @24V.
If you use a singel 340W Panel, the MPPT 75/15 will simply overheat and burn out.
It happen several years ago to me, because I have 3 Panels 100W and usually charge only a 24V Battery, but when I had a Battery problem with my Sprinter, which has only 12V, I cooked the MPPT to dead.
Your experience must be unusual/anomalous. Or it was wired wrongly when it burnt out.
As long as the VOC doesn't exceed 75V at any time and Isc not exceeded, there's nothing wrong with this proposal using a Victron controller..
You're fine. So long as your Voc (from panel specs) is under 75V, you're good to go. The MPPT will manage the current. As others have pointed out, you won't get full value out of the panel
