Solar help... Mppt or PWM

OP,

If you are not aware we're discussing those max amps at noonish. Flat mounted or fixed tilt you don't get that all day long. A fully tracked panel does much better of course but they and generally not practical for a RV.

Last week I dug a 230w panel out of a snow bank and set it in direct sun. Altitude AND freezing cold resulted in over 17a when I normally see 15a from the panel. The same conditions had my 220w jump to over 40 Voc briefly and hold at 38v working. Well above it's rating.

Careful going over those passes in the winter time. lol

JiminDenver wrote:
The max I have seen from my 250w panels is 18.5a on MPPT. On PWM they will put out 10+ amp at altitudes we camp at.

Good information. 250/14.8 = 16.9A for bulk flooded battery charging. No reason IMHO to consider amps at 12.0V.

So 16.9A for nominal conditions and the panel pointed directly at the sun. More amps are available with lower temperatures, clearer sky, etc. which Jim in CO implies.

I have used the Eco-w controllers for years. a good combo with your panel as long as the feature set meets yosur needs. The biggest thing is it does not have temp compensation nor voltage sense.

The max I have seen from my 250w panels is 18.5a on MPPT. On PWM they will put out 10+ amp at altitudes we camp at.

So as stated below the question is what MPPT to get.

Reading a few links on this it seems the consensus is the voltage needs to be raised to 14.8 in the controller. I see morningstar has this but I have not looked up the ecoworthy yet.

102 bucks sounds right up my ally for the eco worthy. Ill try to get a pic of the panel tag later..

I planed on putting the mppt in the front compartment so I would have a short run of #6 cable to the batterys. Then get a 25 ft whip for the panel and while camping put the panel up on the ladder racks on my pick up..

The panel is heavy.. 50 lbs?

I use a Morningstar MPPT-15 w/235 W panel. You would be giving up 5 A in ideal conditions if using the same. The Ecoworthy 20 A was talked about nicely in another recent solar thread on this Forum. The Morningstar has a lot of functionality and has battery temp compensation available.

PWM would be a bad idea with this type of panel - you'll lose half the power. So the question is not "PWM or MPPT" but "which MPPT".

Ecoworthy 20, while being pretty basic, is a good fit indeed. I wouldn't want it with my batteries - he is "too fast", so to speak ;) but then, I wouldn't want a solar smaller than 400W either.

Moved from Technology Corner

Hi,

Because it is a high voltage panel an MPPT controller would extract more power than a PWM one.

250/30 = 8.33 amps

So if you use a PWM controller the solar harvest would be about 8.33 amps. There may be a risk that the PWM would not appreciate having 30 amps thrown at it, and it might let out the "magic blue smoke".

On the other hand, with an MPPT controller harvest would be about 17 amps.

The panel is a good fit for an ecoworthy 20 amp MPPT charge controller. They cost about $102.00

For a high voltage panel like that you basically have to use an MPPT controller. Yes, in great conditions you might see 20 amps out of the controller (not the panel) because 250 watt/ 12 volts = 20.8 amps. This would take very ideal conditions but it can happen.
You can actually use this panel, or any panel for that matter, with a PWM controller, you'll just never get more than the Imp out of it which is probably about 8 or 9 amps. You'd be wasting half your potential power.