Solar on Top of Pergola / Patio Cover?

[lkstaack]

I am researching residential solar for the San Diego, CA area. I have a large roof, but only a small portion of it has an unrestricted view of the south. The rest is east and west, and partially covered by tree shade. I guess about 3 kw of the 5 kw worth of panels I want will fit on the southern facing roof. However, I have a fair sized patio cover / pergola adjoining the house adjacent to that roof. I haven't read about anyone installing solar on a patio. Does anyone know if it is done?

My patio cover is supported by 6x6s sunk into 18" of concrete footing on one side and screwed into a house rafter on the other. I have the option of installing it on a hillside with unrestricted southern views, but suspect that it would not be cost effective to do so. Any experience or insight would be appreciated. Thank you.

[bcroe]

I am researching residential solar for the San Diego, CA area. I have a large roof, but only a small portion of it has an unrestricted view of the south. The rest is east and west, and partially covered by tree shade. I guess about 3 kw of the 5 kw worth of panels I want will fit on the southern facing roof. However, I have a fair sized patio cover / pergola adjoining the house adjacent to that roof. I haven't read about anyone installing solar on a patio. Does anyone know if it is done?

My patio cover is supported by 6x6s sunk into 18" of concrete footing on one side and screwed into a house rafter on the other. I have the option of installing it on a hillside with unrestricted southern views, but suspect that it would not be cost effective to do so. Any experience or insight would be appreciated. Thank you.

An unobstructed hillside could give excellent performance. If operated as a DC string of 300
or 400 VDC, power loss over some distance would be minimal. Some of my panels are over
600' from the house. You might need a fence. Bruce Roe

[lkstaack]

An unobstructed hillside could give excellent performance. If operated as a DC string of 300
or 400 VDC, power loss over some distance would be minimal. Some of my panels are over
600' from the house. You might need a fence. Bruce Roe

I'm sure you are right. However, how much longer would it take to return my investment on a 5kw system if it required 150 ft of trenching uphill, pouring footings and constructing a frame to hold it?

[sensij]

As long as the structure meets the engineering requirements, the panels should be able to be installed on a patio cover. A qualified installer should be able to look at it and let you know if it will be an option, and many will come out and make a proposal without any commitment from you.

[J.P.M.]

I am researching residential solar for the San Diego, CA area. I have a large roof, but only a small portion of it has an unrestricted view of the south. The rest is east and west, and partially covered by tree shade. I guess about 3 kw of the 5 kw worth of panels I want will fit on the southern facing roof. However, I have a fair sized patio cover / pergola adjoining the house adjacent to that roof. I haven't read about anyone installing solar on a patio. Does anyone know if it is done?

My patio cover is supported by 6x6s sunk into 18" of concrete footing on one side and screwed into a house rafter on the other. I have the option of installing it on a hillside with unrestricted southern views, but suspect that it would not be cost effective to do so. Any experience or insight would be appreciated. Thank you.

The patio cover may have some issues when it come to additional loadings, I'd guess primarily wind, as a result of adding panels, especially since (if ?) they will likely be non horizontal. As for ground mounting an array, added expenses may make it non cost effective.

[bcroe]

I'm sure you are right. However, how much longer would it take to return my investment on a 5kw system if it required 150 ft of trenching uphill, pouring footings and constructing a frame to hold it?

Once the system requirements are solid (3KW, 5KW?), you can see what options are available,
and compare costs on each. You have a good location for consistent sun. Keep in mind, an
array which has no shading issues and allows optimum panel orientation, will considerably out
perform an array without those advantages.

Some DIYs have built arrays largely on treated wood and minimum or no concrete, at minimum
cost. Some of us don't want that stuff on the house. Others may not want to give up the land.
Check it out. Bruce Roe

[CA_Tom]

I'm sure you are right. However, how much longer would it take to return my investment on a 5kw system if it required 150 ft of trenching uphill, pouring footings and constructing a frame to hold it?

Trenching - ditch witch is ~$700 for a week of rental. (or $200/day)
You can go as shallow as 6" deep if it's hard to dig material - but 6" deep would require IMC or rigid conduit (more expensive)
You could even do directly under a 4" thick concrete slab (but has to go at least 6" to each side of the conduit)
So if you want stairs /walkway going down that hillside, you could put it under the cement wallkway/stairs.

If it's a very difficult to dig site (ex. large boulders/slabs of rock that make it virtually un-diaggable) another option would be to have the conduit above ground.
I'm not sure what the rules are then - but I'd expect you'd have to keep the conduit protected from mechanical damage and not a trip hazard. (probably if it were part of a fence or something.)

as for ROI - if it's nearly on the ground I think it's going to be similar price and maybe cheaper. You can probably do a cheaper rack system (like PT lumber) And racking isn't a minor expense. Concrete is going to be an extra expense wouldn't otherwise have - but you won't need the attachments from roof to rails - and at $10+ each those add up quickly too. Probably you'll have to have some sort of fencing to keep anyone from getting to the wires on the back - I would expect you can do that without spending much.

[russ]

if it's nearly on the ground I think it's going to be similar price and maybe cheaper. You can probably do a cheaper rack system (like PT lumber) And racking isn't a minor expense. Concrete is going to be an extra expense wouldn't otherwise have - but you won't need the attachments from roof to rails - and at $10+ each those add up quickly too. Probably you'll have to have some sort of fencing to keep anyone from getting to the wires on the back - I would expect you can do that without spending much.

Ever done that? Ever built a pole mounted unit? Ever watched pressure treated wood warp over time?

[lkstaack]

Once the system requirements are solid (3KW, 5KW?), you can see what options are available,
and compare costs on each. You have a good location for consistent sun. Keep in mind, an
array which has no shading issues and allows optimum panel orientation, will considerably out
perform an array without those advantages.

Some DIYs have built arrays largely on treated wood and minimum or no concrete, at minimum
cost. Some of us don't want that stuff on the house. Others may not want to give up the land.
Check it out. Bruce Roe

I'll definitely look into it. Perhaps a more effective location will offset the extra costs through fewer panels. I'm having a couple of solar outfits coming over next week. Everyone I've talked to though seem reluctant to deviate from the normal roof mounted system.

[lkstaack]

Trenching - ditch witch is ~$700 for a week of rental. (or $200/day)
You can go as shallow as 6" deep if it's hard to dig material - but 6" deep would require IMC or rigid conduit (more expensive)
You could even do directly under a 4" thick concrete slab (but has to go at least 6" to each side of the conduit)
So if you want stairs /walkway going down that hillside, you could put it under the cement wallkway/stairs.

If it's a very difficult to dig site (ex. large boulders/slabs of rock that make it virtually un-diaggable) another option would be to have the conduit above ground.
I'm not sure what the rules are then - but I'd expect you'd have to keep the conduit protected from mechanical damage and not a trip hazard. (probably if it were part of a fence or something.)

as for ROI - if it's nearly on the ground I think it's going to be similar price and maybe cheaper. You can probably do a cheaper rack system (like PT lumber) And racking isn't a minor expense. Concrete is going to be an extra expense wouldn't otherwise have - but you won't need the attachments from roof to rails - and at $10+ each those add up quickly too. Probably you'll have to have some sort of fencing to keep anyone from getting to the wires on the back - I would expect you can do that without spending much.

I've rented a trencher and trenched before, but not into the clay and cobble soil of my neighborhood, and definitely not on a slope that is barely walk-able. It may have to be hand dug. A ground mounted system really appeals to me, but not if it's going to increase the costs alot.

[bcroe]

Ever done that? Ever built a pole mounted unit? Ever watched pressure treated wood warp over time?

I am watching my 66' array, but after the first (super cold) year, there is no change. The
plan was that it would last at least 5 years, and 10 was a possibility. By that time I'll
have another solar plan to replace the mount.

I used aluminum panel rails with stainless bolts. Where a bolt holds aluminum to treated
wood, I inserted a linoleum washer, since (I'm told) they react together badly. Bruce Roe

[russ]

I've rented a trencher and trenched before, but not into the clay and cobble soil of my neighborhood, and definitely not on a slope that is barely walk-able. It may have to be hand dug. A ground mounted system really appeals to me, but not if it's going to increase the costs alot.

At least you can throw the material from the excavation downhill!

[Mike90250]

I've rented a trencher and trenched before, but not into the clay and cobble soil of my neighborhood, and definitely not on a slope that is barely walk-able. It may have to be hand dug. A ground mounted system really appeals to me, but not if it's going to increase the costs alot.

A day's rental of a mini-excavator will tear right though that stuff. I did a 1,000' line, on a hill, and took out trees, dug the trench in 2 days. Tried a ditch witch, and when it hits a rock, it throws the belt, 15 min to put it back on, and re-do the covers.

[CA_Tom]

Ever done that? Ever built a pole mounted unit?

?
Where are you getting pole mounted unit?
OP is talking about having it on a south facing hillside - I'm guessing <1' from the ground to the panels.

Ever watched pressure treated wood warp over time?

I've seen plenty of fences built with PT wood for the bottom rail - and with both ends fastened to the cement they don't warp much. Even the vertical posts that are done with PT wood usually stay fairly straight even though they're most securely fastened at the bottom and the top can move more.

[russ]

?
Where are you getting pole mounted unit?
OP is talking about having it on a south facing hillside - I'm guessing <1' from the ground to the panels.


I've seen plenty of fences built with PT wood for the bottom rail - and with both ends fastened to the cement they don't warp much. Even the vertical posts that are done with PT wood usually stay fairly straight even though they're most securely fastened at the bottom and the top can move more.

1) height - doubt it - I would certainly go at least a bit higher - for ease of construction.

2) You have done little with pressure treated wood apparently - it comes warped and gets worse over time - with a fence it makes no difference but to fasten a panel to it? Come on.