Even small amounts of shade can cause MAJOR power interruption in a solar array.
If you shade only one cell in a module you will likely see a 33% power reduction from that module. If you shade a row of cells in one module, you will see a devastating 90% power reduction. The even bigger problem is that every module in the series string will see the same power reduction. So when that chimney casts a shadow over one row of cells on the last module in a string of 13, you lose 90% of the power to ALL 13 modules
Most experienced site assessors use the Solmetric Suneye or Solar Pathfinder to determine shading problems before determining how large an array can be mounted in the desired location.
Micro-Inverters (like Enphase) and the National Semiconductor SolarMagic control can help minimize the power loss due to shading, but solar pros agree that every effort should be made to ensure ALL modules are shade free between the hours of 9AM and 3PM.
ps. even shadows from power lines and bird poop (especially pigeons!) can cause a noticeable power reduction.
Lay-In lugs are sold in ten packs (part number 051-03414), with the special “thread-forming” screw. That #10-32 “thread-forming screw” that comes with the lugs in the ten-packs, is a very special screw, and is very hard to find out there in the world. We had to contract with a screw manufacturer to get them. They are different than a “thread-cutting” screw, or a “self-tapping” screw. Both of those type of screws actually cut out some of the metal from the module frame as they “cut” the threads. This creates a microscopically loose thread connection that can allow oxygen in and create corrosion over time. They are not usable for a permanent ground connection. The “thread-forming” screw actually “folds” the metal, and “forms” a thread in such a way that there is an oxygen-free junction between the frame metal and the screw. This produces a better electrical “bond” and a proper ground connection that will last over time.
