K8MHZ
Senior Member
- Occupation
- Electrician
For roof mounting, flush with about a 3 inch air space, are there any other means beside the custom made rail systems suitable? The rails cost nearly 8 bucks a foot. Adding the cost of the rest of the hardware that adds 50 bucks or so to each 3'x5' module. The 33 module array I just drew up would take over 1500 dollars of mounting materials.
I checked Uni-Strut and although they claim to have a product suitable, I didn't see much other than the stuff I already know about. Uni-Strut isn't cheap, either, and there is going to be extra labor due to having to drill holes for L-brackets.
Would it be a travesty to consider pressure treated lumber?
Module costs are not only coming down, but 'scratch and dent' seconds are now showing up for about $1.30 per watt. Good brand inverters are becoming available used for about 1/3 of what they cost new. Also, new technologies are making inverters much smaller, thus less cost and easier installation.
None of the above is true for the mounting systems. We used Uni-Rac in school. Yes, it is a great product, but it costs about $7.70 per foot, not including hardware.
Uni-Strut would be easy to use if we only wanted 1 5/8" of air space. To get 3 inches, 'back to back strut would be needed, putting an open side toward the roof. Also, the back to back stuff doesn't have holes in it. I have seen electricians use 'front to back' by bolting them together for hanging pipe. Although fine for that, I don't think such a configuration would be sturdy enough for mount solar modules.
Right now, the RROI (rate of return of investment) for systems that cost 6-7 bucks per watt is around 2 percent. (At 12.4 cents per kWh). 2 percent is not worth taking money out of a 4 percent interest rate CD to 'invest' in a PV system.
If we can get the cost down to 5 bucks per watt, the investment return figured as interest starts becoming competitive with CD's and savings accounts.
I checked Uni-Strut and although they claim to have a product suitable, I didn't see much other than the stuff I already know about. Uni-Strut isn't cheap, either, and there is going to be extra labor due to having to drill holes for L-brackets.
Would it be a travesty to consider pressure treated lumber?
Module costs are not only coming down, but 'scratch and dent' seconds are now showing up for about $1.30 per watt. Good brand inverters are becoming available used for about 1/3 of what they cost new. Also, new technologies are making inverters much smaller, thus less cost and easier installation.
None of the above is true for the mounting systems. We used Uni-Rac in school. Yes, it is a great product, but it costs about $7.70 per foot, not including hardware.
Uni-Strut would be easy to use if we only wanted 1 5/8" of air space. To get 3 inches, 'back to back strut would be needed, putting an open side toward the roof. Also, the back to back stuff doesn't have holes in it. I have seen electricians use 'front to back' by bolting them together for hanging pipe. Although fine for that, I don't think such a configuration would be sturdy enough for mount solar modules.
Right now, the RROI (rate of return of investment) for systems that cost 6-7 bucks per watt is around 2 percent. (At 12.4 cents per kWh). 2 percent is not worth taking money out of a 4 percent interest rate CD to 'invest' in a PV system.
If we can get the cost down to 5 bucks per watt, the investment return figured as interest starts becoming competitive with CD's and savings accounts.