I own 3 Lion Energy solar panels. These 100 W panels output 52V VOC (as measured by my voltmeter). I'd like to run 2 or 3 of them (in series), potentially producing 104V or 156V VOC, in order to charge the LiFePO4 batteries in my travel trailer. Will the Victron SmartSolar MPPT 100/20 handle two of these solar panels? Will a SmartSolar 150/XX handle all three of my panels? Or should I use a 150/XX and only run two of them?
The voltage (VOC) limit is a hard limit. You can parallel connect them but not series (to add up the voltage). You could probably do all three 100W divided by 52v VOC means they only output 2A or so? Let me add I have no experience with these panels.
Probably should check them with a meter, there are no specs on the website. but they can at most put out 25A in theory (300W / 12V = 25A assuming it is a 12v system)
https://www.victronenergy.com/mppt-calculator this page will recommend the best one for your panels and set up.
Thanks for your reply.
Here are the specs from my Lion energy panels from a sticker on the device:
Maximum Power: 100W
Current at Pmax (Imp): 2.85A
Voltage at Pamax(VMP): 35V (Should be 'Pmax'??)
Short-Circuit Current:ISC): 3.13A
Open-Circuit Voltage: 43.2V
I am told the panels run in parallel when chained together using the Anderson cables provided. Thus even with all 3 panels connected, I should have no more than 44V VOC. (My voltmeter measures closer to 50V, but may be inaccurate?)
The Lion panels are intended for a 24V solar generator system. Lion support tells me that I can only charge a 24V system with my panels. I do not understand how a downstream charger controller would know or care about that.
At any rate, I put the panel's specs into the calculator you gave me a link for, and it suggests the Victron SmartSolar MPPT 100/20. I want to charge 12V LiFePO4 batteries connected in parallel. Do I correctly conclude this will work?
Many thanks in advance!
best
-Steve
when you use an MPPT controller there is dc to dc conversion that goes on. You still have to match the panel voltage to ensure that the panels can produce a higher voltage than the batteries require. My understanding is that the Victron MPPT controllers require at least 5 V higher to come from the panels than the voltage of you battery pack. Once the MPPT starts up it can handle the panel voltage to fluctuate a little lower (I think down to 1V above battery voltage).
I prefer to connect the panels in series to generate the highest array voltage for two reasons, you don’t have to use heavier cables as the current is kept to that produced by a panel and at sun rise and sunset the panels will get/keep the controller started earlier and going a bit longer.
Taking the above into consideration you also have to take the cost of the system into account and given you only have 300W to deal with it would be a bit hard to justify a 150/35 MPPT. A 75/15 will handle your three panels in parallel from a power perspective on a 24 V battery pack and will handle your max Voc.
