Nice! How does it do on say a 50% cloudy day with strong sunshine between clouds? My Vmpp will quickly jump from 16 or 16.5 in the sun down to 14 Vmpp when a cloud comes over. If the controller is set at 16v I get essentially no output until it passes. If set to 14v quickly, I get max power. In some shade conditions the Unisolars can produce almost 50% power into my AGMs compared to full sun.
What is the quickest user selectable sampling interval available?
Jim
I've not measured the actual time it takes to track a 16v -> 14v change in MPP, but a 2v change would be tracked quickly...I would imagine less than a second, based on observing the change in pulse width on a scope.
The shortest user-adjustable interval is 10 minutes.
Thinking about sense lines for small PV systems (as in RV's) some more made me realize they're not needed. There are exceptions, but the only time the charge controller outputs max amps is during boost. You don't need sense lines at this time as the system is current limited by the maximum power point. It doesn't matter how much line drop there is. The system is under current control: I ~ Pmpp/Vbat. At the onset of absorption, it can be an issue. But current quickly tapers, making line drops small and hence not needing sense lines.
I disagree. The onset of absorption may occur too early if the battery voltage is not being measured correctly at higher currents. As well, if you have significant loads that the controller is supplying current to in absorb and float modes, the controller may be undercharging the batteries during those times. Believe me, I wouldn't go to the trouble of adding the feature if there wasn't any benefit of doing so. Also, you're missing the negative sense wire in your schematic a few posts back, so you're not compensating for the voltage drop across the negative battery wire in that design.
