Elecgric Vehicles - F250 Lightning - Event Date: 16 Mar 2022

You can get micro inverters which completely isolate individual modules to limit shading impacts. But if your site is heavily shaded the performance will still be bad. Find a different site or cut some trees. If you can't do that then probably solar is not for you, or at least not unless you move.

Cutting down my organic towers (trees) is not gong to happen. I have had to cut too many already. Organic towers means I use some of the trees to support my amateur radio antennas. From the calculator, I figured that I could cut my power bill, but not eliminate it. I have the wrong orientation and vent stacks on the best roof surface available. We only have .28 acres, so there is no space to put a ground-mounted system either.

Originally posted by Olddawgsrule Originally posted by GlueGuy If you have partial shade, it's also good to isolate panels such that they don't fight each other when some of them are shaded. I do believe this is where diodes come into play. If concerned add inline.  As far as shade goes, capacitors come to mind.. How many, at what size and if efficient for cause to be be determined.  I was just down in Baja and didn't see a cloud for nearly a month in the Southwest. Is solar worth it, ya down there! Up here, it takes some doing to come even close to what they have available.  Can we do it? Ya.. with some effort.. If so willin'  Again, I approach this from a different propestive than draggin' a trailer..

Sorry olddogsrule but you have lots of misinformation here. You are mixing up grid tie and off grid system design. They are very different animals.

Bypass diodes are installed in all PV systems above 12V, which of course means all grid tie systems. This is a UL listing requirement to prevent fires within the array. Typically the bypass diodes protect every group of 18 series cells or so, allowing current to flow around each group if there is shading on one or more cells in that group. The shading might not be trees, it could be just a chunk of bird poop or a leaf obscuring all or part of a cell. So the bypass diodes are always required above 12V regardless of location. They aren't needed at 12V because there isn't enough voltage in the system to get a group of cells to go into reverse bias and turn on the diodes.

So bypass diodes are mean for safety purposes not for shade mitigation. They will do some shade mitigation but if the shading is extensive then they won't help grid tied systems much, because grid tie systems run at high voyages with many modules in series, and you will lose the whole series string once one of two bypass diodes turn on.

The micro inverters or other module level power electronics devices can do a much better job in mitigating shade, because they limit the effects to individual modules. Starting with the 2017 NEC you need to have module level arc fault detection and shutdown on roof mounted resi systems anyway so you might as well get combination devices which serve both to provide the safety as well as the shade mitigation functions.

Inline diodes are blocking diodes to keep current from flowing backwards into the array at night in low voltage battery charging systems. Nothing to do with shading. They used to be used with older charge controllers which didn't open the circuit at night, but are generally not needed with modern controllers. Don't install them. Ditto on capacitors, they will do nothing for shading.

Don't believe that you can't do grid tied solar in the NE. There is plenty of it going in all the time.
There is much less difference in annual solar output between the SW t and the NE than you might think. There is a big difference in winter worst month performance but that's not important if you're grid tied and on net metering, where you true up with your utility company annually. Most of the production comes in summer anyway. Winter performance is what matters for off grid systems that are meant to be used year round. These systems essentially waste the excess summer production from the solar array, so annual production isn't important for them.

For sure if you're considering a new roof in the next couple of years you want to do that either first or as part of the solar project.

Even if you're not going to install solar right away consider getting the stanchions for the solar racking installed as part of the roof project. It's much easier as well as more leak proof if you get the stanchions flashed in as the shingles are going on. Any decent solar installer can attach those to your rafters after the old shingles are stripped off, then the roofer can come along behind and install the new shingles. Or you could DIY the stanchions once you have your solar layout done.

https://solarmagazine.com/solar-roofs/solar-shingles/