Solar Controllers--Don't be a Sucker! :(

smkettner wrote:

BFL13 wrote:
I am still stuck on jimindenver's results getting about 15a with 235w and 24v with MPPT, while two 120v 12s will do 15.2 at Isc (my 120 I had before got its 7.6a Isc no problem)

Is the MPPT rated 15 amps only? That would limit power.

No, he has that Eco 20amper. Some others reported 15a with their 235s but they have those 15L controllers that do clip at 15a.

However jimindenver has said he got his results in some haze/smog and might do better up his mountain. At least he does have a portable and aims it so panel orientation is not an issue with his max amps results.

That 23a with MPPT on 328w would be a good comparison with my 21a and 330w with PWM, but he has flat panels and we don't know how high the sun was to know if he would have got higher with pointing. That would show a small percentage gain with the MPPT. As it is, 23 over 21 is 2/21 = 9.5% not far off Salvo's 8%.

(I am saying getting two more amps at high noon wouldn't help me since I already get the job done with the 21 I do get.)

The other report here was 20-27a with 370w and MPPT which is in the ball park for the 23a PWM would get.

It is maddening to have these hints that 24v and MPPT get very similar peak amps to 12v and PWM, but no confirmation. Need a lot more data.

My point remains that you get about the same--maybe a few more--with MPPT but no big deal. I did say that first, you need to "size"
your solar with your battery size and camping usage. With that, the type of controller doesn't matter--you are getting the job done.

Be a special case that you could only get the job done by going MPPT where there is no way to get it done with PWM and save a ton of money.