as new to this and since i want to be sure, i need to ask this
i bought a solar panel with this characteristics :
220W (±5W)
Open Circuit Voltage 21.5V and Optimal Operating Voltage 18.4V
Short Circuit Current 12.4A and Optimal Operating Current 11.9A
Recommended Ambient Temperature -20°C to 85°C (-4°F to 185°F)
Temperature Coefficient of Rated Power -(0.30±0.02)%/°C
Temperature Coefficient of Open Circuit Voltage -(0.25±0.03)%/°C
Temperature Coefficient of Short Circuit Current +(0.045±0.015)%/°C
And i want to charge with it a 12V lifepo4 battery 100Ah
And i want to buy an MPPT
as far as i can understand MPPT 75/15 suites me well but i see it is the only one that has no heat sink and its gonna be in high temperatures like on sand (protected ofcourse) with 40 C°
Also i know that panels may produce slighly bigger Amps or Watts
So is it best for me to go with the MPPT 75/15 or should i go one step further and get the MPPT 100/20 or 100/15?
Just get the 100/20. It’s a freak, does 12v 24v, 36v 48v. Even if you dont need it now, you might, and like you noticed, it has a heatsink. 200 odd watts is nothing, maybe 160W max charge. You may want to add another later, the 100/20 will give you a bit more and won’t get hot.
This doesnt need calculations but it says MPPT 75/15 but the watts are at my solar panels maximum 220W and with solar panel (±5W) i dont know if i will damage it cause of Amps. In Volts ofcourse it will never reach max volts but in amps and thus the watts i dont know. Thats why i ask…
Yeah, i think of it like this too, i wont update the panel, cause this is for a specific reason and only. But i do it due to temperature missoperations and due to 220W (±5W) of my panel output.
If the Amps goes over 15Amps i may damage mppt but since i dont know i had to ask for opinions.
The other thing is that it has heatsink and yeah giving more power than it will get it may have lower temperatures while working but i dont know.
The only missadvantage is the heat sink and the dimensions of it in front of 75/15 but for the sake of working fine i think 100/15 or 100/20 will be better
Thank you for your time taking these photos. Yes that what i was talking about with the heatsink but since it will work “better” than the other i think i ll go for the 100/20. I would like to take the 75/15 but its to close to the maximums and i dont want any problem to occur.
Thanks again Owen!
Vassili,
Victron charge controllers are protected from overcurrent and overtemperature. The 75/15 can do 220W at 12V. If more PV power is connected, the controller will limit input power. That is, in the (rare) case that your panel will output more than 220W, the mppt will limit current. Also, all controllers are -30 to +60°C (full rated output up to 40°C), so even if the sand is hot, they are not destroyed.
Now, the 100/20 is a more versatille product (can go to 48V, if you ever need it), has heatsink because it can charge to over 1kW. Its (protected) load output can drive 20A (vs 15A of 75/15 or 100/15) - if you drive light loads (like… lights!), it is a nice feature. On the other hand, the 100/20 is almost 50% pricier than 75/10. Check also no load (and/or “night”) currents.
Your call, since you start now, I’d go with the 100/20 (if it fits).
