Guys I can’t seem to find a direct answer to this as most topics I find seem to go off tangent. Not as cut and dried as hoped I know but if I plan on using a correctly rated MPPT controller, likely the 100/50 which voltage panel will give me most output in simple terms when charging a 12 volt battery.
Comparing two 200watt panels. One operating voltage 31.3 @ 6.3 amps the other 19.2 volts @ 10.42 amps. I understand the MPPT can convert some of the voltage to current but do you actually get more amps output from the MPPT with the 36 volt panel and is there a calculation for how much if so.
Watts are watts, for the most part. You’ll get very slightly lower conversion losses from a higher-voltage panel than a lower-voltage panel, but it’s not going to be enough to be worth spending too much time thinking about.
Either way you’re likely to get roughly 12 to 13A of charge current into your 12vNom battery bank from a 200w panel, so if you’re talking about only a single panel there’s no reason to use a 100/50, you can use a 75/15.
If it was me I’d use the higher-voltage panel just because it’s likely to be able to start charging earlier in the morning, and keep charging later into the evening.
Thanks Justin. I’ve never looked a the option of higher voltage panels so just wasn’t sure how they compare. Probably was getting hung up on the amperage rating difference.
I deliberately didn’t go too far into my set up as I’m comfortable with that and didn’t want to start something on that just needed to get me head around the different output ratings. I will be running 2 x 200w panels hard mounted plus have a folding portable for back up when inconvenient to park in sun etc. Plus the hard mounted are on a pivoting rooftop tent roof so angle will be additionally compromised sometimes, which is the other reason for the portable. Hence why the 100/50.
If you have the space I’d go for 3 75/15, costs a few cents more, but you’ll allways know what the individual panels are doing and have some redundancy .
Do not forget that you need the solar to be 5V above the battery voltage to start charging. If you have lithium this means you need more than say 18.5V to start charging. If you panel is 19V Vmp and higher Voc you should be OK.
From the manual
8.3.1. PV voltage too low
The solar charger starts charging when the PV voltage is 5V above the battery voltage. Charging continues if the PV voltage remains 1V higher than the battery voltage.
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