Expected Solar Yield, Key West
Can anybody tell me the expected daily yield of a 250 w panel flat on the roof at 24.5 degrees N. Dec, Jan, Feb Thanks Joel
Forum Discussion
Yes, rear roof - usually - slopes to the back. Equal height brackets will result in the needed panel slope. BUT, 2 L-brackets near the rear side parallel to the rear side will not be plumb, they will be tilted back - because of this slope. The other 2 L-brackets parallel to the rear side, will be plumb, because the roof has no back-facing slope there. As a result, you will have the vertical walls of the rear pair of brackets not parallel to the vertical walls of the front pair of brackets. It will still work.
Mounting order - suggested by others - was as follows:
Install 1/4" stainless rivet nuts. Darn expensive $4 a piece at McMaster. With 4x4 angle you can probably use a lock-nut on that 1/4" bolt, much cheaper. If you remove one rail, you can use lower brackets, but then lock-nut will be difficult to attach.
- Drill holes in vertical legs of L-brackets about 3/4" from the top. Attach brackets to riv nuts, slightly loose. Put the panel on all 4 feet, mark the footprints of the brackets.
- Clean the roof rubber within the marked 4 footprints, soapy water and denaturated alcohol. Not just "wash" - rub it thoroughly, until you don't see whitish powder coming off the EPDM roof anymore.
- Mark location of anchor holes in brackets feet, making sure the holes are not next to some screw in the roof. Drill 3/16" holes in brackets.
- Attach brackets again, place them on the marked and cleaned footprints, mark and drill pilot holes in the roof.
- Put one end of panel on a big piece of lumber, spread roof sealant over one footprint. Dicor, Geocel EPDM, or at least Urethane outdoor sealant. Don't procrastinate, Dicor and Geocel will "skin" quickly. Lower the foot onto the roof, lubricate #10 screws with roof sealant, drive them into the foot, cover their heads with sealant too. Repeat on other 3 corners.
Some brackets might have anchor screws in different location. I marked the brackets to know which one is rear left, rear right, front left, front right.
There are other ways to skin this cat. You might consider 2-piece Z-brackets instead of 1-piece L-brackets. 2x2 angle on the roof, another 2x2 angle attached upside down back-to-back, with 2 screws joining both angles, to make a Z-profile. Then you can use the holes in the panel bottom lip, maybe drill some more. Easy.
Also, I would be tempted to mount the panel on the roof rack rails, drilling through the rail and using machine screws and lock-nuts into the holes in the panel bottom lip.
Hardware:
It should better be stainless. I could not find stainless #10 "deck screws" with dome or hex head, they probably don't exist. So I used #10 sheet metal screws on some brackets, and some serrated thread screws that are supposedly better for plywood.
Cable from panel:
I hope you ordered MC4 extension cable AWG 10, as you don't need any other kind of cable, and that it is DOUBLE length.
Switches:
Don't know what Bluesea "switches" you bought and what for. Their big battery switches are for battery select/disconnect, you might not even need those. What you need, is a controller fuse or breaker, and some panel switch (doesn't need to be a fuse).
Controller location:
I would mount it in some storage where you could barely see the display when you open the hatch. Otherwise you'll be tempted to check on it several times a day, and there isn't much need.
Mounting order - suggested by others - was as follows:
Install 1/4" stainless rivet nuts. Darn expensive $4 a piece at McMaster. With 4x4 angle you can probably use a lock-nut on that 1/4" bolt, much cheaper. If you remove one rail, you can use lower brackets, but then lock-nut will be difficult to attach.
- Drill holes in vertical legs of L-brackets about 3/4" from the top. Attach brackets to riv nuts, slightly loose. Put the panel on all 4 feet, mark the footprints of the brackets.
- Clean the roof rubber within the marked 4 footprints, soapy water and denaturated alcohol. Not just "wash" - rub it thoroughly, until you don't see whitish powder coming off the EPDM roof anymore.
- Mark location of anchor holes in brackets feet, making sure the holes are not next to some screw in the roof. Drill 3/16" holes in brackets.
- Attach brackets again, place them on the marked and cleaned footprints, mark and drill pilot holes in the roof.
- Put one end of panel on a big piece of lumber, spread roof sealant over one footprint. Dicor, Geocel EPDM, or at least Urethane outdoor sealant. Don't procrastinate, Dicor and Geocel will "skin" quickly. Lower the foot onto the roof, lubricate #10 screws with roof sealant, drive them into the foot, cover their heads with sealant too. Repeat on other 3 corners.
Some brackets might have anchor screws in different location. I marked the brackets to know which one is rear left, rear right, front left, front right.
There are other ways to skin this cat. You might consider 2-piece Z-brackets instead of 1-piece L-brackets. 2x2 angle on the roof, another 2x2 angle attached upside down back-to-back, with 2 screws joining both angles, to make a Z-profile. Then you can use the holes in the panel bottom lip, maybe drill some more. Easy.
Also, I would be tempted to mount the panel on the roof rack rails, drilling through the rail and using machine screws and lock-nuts into the holes in the panel bottom lip.
Hardware:
It should better be stainless. I could not find stainless #10 "deck screws" with dome or hex head, they probably don't exist. So I used #10 sheet metal screws on some brackets, and some serrated thread screws that are supposedly better for plywood.
Cable from panel:
I hope you ordered MC4 extension cable AWG 10, as you don't need any other kind of cable, and that it is DOUBLE length.
Switches:
Don't know what Bluesea "switches" you bought and what for. Their big battery switches are for battery select/disconnect, you might not even need those. What you need, is a controller fuse or breaker, and some panel switch (doesn't need to be a fuse).
Controller location:
I would mount it in some storage where you could barely see the display when you open the hatch. Otherwise you'll be tempted to check on it several times a day, and there isn't much need.
