Solar Guidance

Salvo wrote:
You're overrating this effect. It's a bonus if you got a solar tracker. The panel needs to be perpendicular to the sun to take advantage of this effect.

A lot of people confuse the lens effect with a cooler, cloud-covered panel. When the sun appears the cooler panel will output more current (for a short time) in mppt mode.

pianotuna wrote:
The folks who are promoting 30 amp controllers are not taking into account cloud 'lensing' effects. Some controllers don't mind this--others it will let out the magic blue smoke.

I think (not sure now) the sun is brighter then from all angles, so I would like to know more about why Salvo says it has to be right on the panel (assume he means close to that)

I have seen "edge of cloud effect" many times, which I take to be the same as "lensing" I am pretty sure (been a while) I got it with my panel fixed facing South at other times than at high noon, but I can't say how far off in angle to the side.

It is seen as a higher than normal Isc on the panel due to above normal insolation. (The sun is much brighter during this time) and this also makes for extra input wattage to an MPPT controller.

Since those times, I have been using my panel on a twirler mostly aimed near the sun, so I am going by memory on that off- angle lensing.

In any case, the extra amps you get in and whether the controller can handle them is the issue. It heats up internally with more amps and the internal heat can damage the controller if it lasts long enough.

That is why the US NEC says to make your controller 1.25 times the array Isc amps to allow for when the panel does more than its rating at times. (Unless the controller has a built- in "clipper" to prevent the amps going above and overheating it)