Was looking at the shade starting to fall on my panels this morning as we head into winter and wondering if there had been any advancements in this technology. I didn't see anything new other than the voltage drop is now down to about 25% of a conventional diode (a gain of about ~+0.3V). But, in reading through the posts had some additional thoughts:
So, this basically bumps up the shaded string's voltage...
No, not a
string of panels. It works on the innards of the panel and bumps up the panel's overall voltage. But yes, internally it bumps up the voltage of a sub-array within a panel by replacing that subarray's diode built into the panel. Which means it should work for inverter or microinverter systems (although probably not as much benefit with micros since the output from a string is very affected by the weakest panel in the string).
...Doesn't that then force current through the inactive cell(s)? If so, is that necessarily good for the cells.
Given a diode affects all the cells in the sub-array I suspect the maxim chip would actually be better for them. But, not an EE, so...
...It has some benefit for a bird poop spot but not much more...
Snowy areas where the bottom can be covered would probably see a big increase too. They might not be very useful for leafy shade, depending on how the shadows traverse the panel through the day and subpanel orientation.
In
NREL's test case, it was somewhat guaranteed to be a success as they used a solar farm setup at their Colorado facility with no shade other than "row" shading during the winter months:
... will be about $3-$4 verses less then $0.50 for bypass diode. The cost-benefit is just not there, especially with the tough panel market price competition.
The chips are almost $5 now, but I'm not sure how you'd calculate the return as it would really depend on your shade characteristics. In NREL's study, the shade always moved across the same subpanel and didn't affect the others.
My neighbor's trees have grown a bit since installation and there are about 3 to 4 panels at the bottom of the line that get affected from November to March. So, here it would only be about $20 for four chips. Let's see... +20% from a panel at half power would be about about +30 watts. So, 120W for four panels. Winter insolation of 4, so 480W/day. 90 days at $0.14/kWh would be $6 value per year. Over 25 years that would be a net gain of $130. So not much value honestly. Also, my shade moves across all the subpanels so I doubt it works as well as the NREL study. It would be nice to see a "leaf" study.