Fence mount solar array

[smcfarla]

I unfortunately have a shaded roof (neighbor's trees that they don't want cut), a small lot (50ft wide) with 12ft setbacks from the property line from town zoning requirements. Obviously ground mount would be obtrusive to my lot, so I think the town will agree to fence mounted panels. My fence is a white vinyl fence with hollow posts, however for the gate posts you can buy a metal i-beam to stiffen them up. I was thinking I could use that for some 400w panels. I am seeing tons of posts of how people want to do this, but nothing really in terms of actual information for "buy this, here are the structural codes". Trying to figure out how I get through the technical challenges to a permit approval. Anyone know of resources to turn to? I'd like to use a mount that tilts the panels at least some to get more production.

 

[smcfarla]

as an addition, I contacted Unbound solar, and while they have packages for roof or ground mount and can help with that, they didn't have any guidance for vertical mount.

 

[zanydroid]

AFAIK there is no pre-engineered vertical mount on the cheap. I’ve seen similar threads to you.

My AHJ actually called around for me to see what people in my town used, no dice. They were happy to accept something that had engineer stamps. I actually wanted to go two rows up on the wall which was even worse. Anyway I didn’t want to learn how to hire and convince an engineer what I wanted to do wasn’t dumb, or prepay for an analysis / design that would end up being unbuildable, so I went back to roof mount. Since this is a pretty uncommon request you will likely have to pay extra billables for the engineer to do research for you.

FWIW in my town fence mount solar would violate the solar specific setback requirements for ground mount.

My advice is to research this with an eye towards failing and convincing yourself not to do it ?. Like call up the AHJ and ask what they think.

 

[zanydroid]

Did you run PVwatts yet? That will tell you the potential output, maybe it would be disappointing enough to cause the fast fail. It was convincing for me.

 

[smcfarla]

Did you run PVwatts yet? That will tell you the potential output, maybe it would be disappointing enough to cause the fast fail. It was convincing for me.

I didn't know about that site until just now, thank you. And you were right...ouch. what a difference between 90° and 45°. wow. I'll consult with a solar installer to see if maybe part of my roof is ok...and then maybe the neighbor would let me "trim" the trees a little? at 90° I'd only have 1/3 to 1/2 of my bill covered for an up front cost of > 10k...totally not worth it. thanks for killing the dream...i guess. ha ha

 

[zanydroid]

I didn't know about that site until just now, thank you. And you were right...ouch. what a difference between 90° and 45°. wow. I'll consult with a solar installer to see if maybe part of my roof is ok...and then maybe the neighbor would let me "trim" the trees a little? at 90° I'd only have 1/3 to 1/2 of my bill covered for an up front cost of > 10k...totally not worth it. thanks for killing the dream...i guess. ha ha

Haha. I’m doing you a service by letting you noodle on something more likely to be a winner.

Trees will murder your ROI. Any amount of shade on a solar panel will cut the output a lot, and in some cases put thermal stress on bypass diodes which are a bit of a wear item.

I have a pretty shaded lot in California under generous net metering sell terms. Turnkey installation for $2.40/Wdc I expect will break even in probably never (they did the shade analysis wrong, also put 1/4 of the panels in terrible locations. The net metering sell terms will expire and get much worse in 15 years, probably by a factor of 4, and there’s a low chance it will break even before then). My DIY install for maybe $1.30/Wdc on properly optimized roof locations (still have bad shade but not terrible than the contractor did) will maybe break even in 8 years

 

[zanydroid]

Ask the contractor to do something like Aurora Shade report on a quick solar panel layout. That combines PVwatts style model with LiDAR simulation of shade.

 

[smcfarla]

Haha. I’m doing you a service by letting you noodle on something more likely to be a winner.

Trees will murder your ROI. Any amount of shade on a solar panel will cut the output a lot, and in some cases put thermal stress on bypass diodes which are a bit of a wear item.

I have a pretty shaded lot in California under generous net metering sell terms. Turnkey installation for $2.40/Wdc I expect will break even in probably never (they did the shade analysis wrong, also put 1/4 of the panels in terrible locations. The net metering sell terms will expire and get much worse in 15 years, probably by a factor of 4, and there’s a low chance it will break even before then). My DIY install for maybe $1.30/Wdc on properly optimized roof locations (still have bad shade but not terrible than the contractor did) will maybe break even in 8 years

I appreciate it. the less/potentially unshaded portion of my roof is in the back, where I have a walkout basement on a 2 story house, so there's no way I'm doing a DIY kit up there...but I'll have a solar company check and see what they come up with and go from there. Here in CT Eversource is psychotically expensive where delivery fees outweigh already high energy costs, so I really want something to offset it a bit. Even though I'm on the shoreline I'm on the other side of a hill so not enough wind for a home turbine either.

 

[zanydroid]

Ok. Make sure you don’t go with a bogus bid that only does PVwatts analysis (which does not do shade). That’s how I messed up and bought the first system that may not break even before I replace the roof and take it off.

 

[smcfarla]

Ok. Make sure you don’t go with a bogus bid that only does PVwatts analysis (which does not do shade). That’s how I messed up and bought the first system that may not break even before I replace the roof and take it off.

I will make sure to ask for the shade report. Thanks again for all the info. I'll check back in when I have more info. May try to pursue a variance from the town for ground mount...but I think that's unlikely to go through.

 

[zanydroid]

Lol, just realized my net metering agreement has 20 years instead of 15. Well it’ll probably exactly break even ignoring opportunity cost…