Hello, I posted a similar question on Arizona Sun & Wind but thought I'd try here also. I have very little south roof space but noticed the inverters all need a minimum number of modules to even operate. I can fit 6 Sharp 208 on my south roof and 7 on the west roof. Do I really need to have 2 balanced strings with 7 modules each, or can I put all of them on 1 string?

Thanks.
T

More details, what is the space available ftxft , not in panels

6 sharps ( each 64" x 40" ) would could be , 5ft x 20ft or 10ft x 10ft

what is the closest ftxft roof area and just curious as why so small? is this even a house roof?

Hello Solar Guppy,

I don't have the exact measurements since my contractor didn't leave them with me. It is part of a house roof and the house sort of has a
|___ shape, with the south roof being the | part. The west faces the street and we are OK using a bit of the west roof but not the whole front roof. Unfortunately, there are 2 sink/toilet vents in the middle of the south roof, thereby breaking up the available space. Actually, I had several contractors tell me they could install the solar modules over the vents, but this one won't. And he doesn't seem to want to hang the panels a bit over the edge - should I push him to do either of that?

Thanks.
T

you can't cover a vent stack and meet code ... its usally no big deal to re-route the stack ... a plummer can do this in an hour if its an open attic

To give you more advise, you have to know the general demensions ... for example, you didn't address if its was 6 by 1 or 3 by 2 or 2 x 3 on the 6 panel south roof.

As for your perference on the larger west roof, if you have one row, another isn't going to look any worse or better. Again, you need to know what the roof demensions are to get anyone to respond with something you can work with. Time to get out your tape measure and do it yourself?

Based on what you have said, I would say you have more options, you need more data to understand the choices to make.

I did a rough measurement from the ground. The south roof has a rectangular part that is about 12 ft by 8 ft plus a triangular extension that is about another 4 feet along the length, i.e. the longest edge is roughly 16 ft. The vents are roughly in the middle of the 12x8 portion.

Forgot to mention that the west roof area we are using is not really visible from the street - it's also a triangular piece blocked by a gable from the rest of the roof that is visible from the street. Dimensions are roughly 16ft wide by 10ft with a triangle edge and one vent in the middle.

Your house is only 16 feet wide? ( south end measurement ) .. or is the south roof 2X longer, wil a gable sticking out the middle?

200 sf is very small ... have you thought about ground mount is the back yard?.

based on your measurments, I think you could squeeze 8 Photowatt 155/165/175's on each surface ... You will have to re-route the stacks ( couple hundred for a plummer) , holes could be re-used for the conduit for the panel to inverter runs

The Photowatts are about 46"x42" ... so only the top panel on the south would over-hang a bit about 1/3rd of the panel, but as long as its on a rail support, shouldn't be a big deal.

IF that won't work, next is use 16 or 20 KC-65's. on each roof. Its a bunch of panels, BUT using smaller panels allows you to get the higher voltage. a grid of 4x4 panels will fit for sure, a grid of 5 x 4 will be tight but should fit as well. The Smaller KC65's would also fit around the stack, but then your going to have serious issues with shadows!.

Installer will have to do a little more work on the racking and wiring with the smaller KC-65's, but is worry free, no risk solution.

Photo-watts would give you 2800 watts, the Kyocera's would give you 2600 watts


If either can be done, then its two balanced strings and you can use a GT-3.3 for the inverter. Having them faced different orientations doesn't make much of a difference for the mppt tracking as tempature is the biggest infulance and being on the same roof will keep the panels pretty close over the day.

Hello Solar-guppy,

The house is wider, but as you guessed, gables mess up the available roofline. The south roof actually ends into the east roof (which is large and faces the back yard but I definitely do not want to put panels there since we get morning fog a lot in CA). The front west roof also is broken up by a gable, but then continues on the other side of the gable right over the front door, so I don't want to put panels there either.

The yard is pretty small, so ground mount isn't really an option. I'm almost at a point of wondering whether to install solar at all

T

Don't get so down ... Using smaller panels is perfect for your type of roof. The only difference for the installer is he has to do more wiring to interconnect the panels .. NO BIG DEAL

On my east-south east I have an array of 20 frameless Solarax 75-watt panels .. this array has been flawless and because its east facing, durring the Summer can out produce my larger west-southwest array as we rain every afternoon for the summer months

http://www.solar-guppy.com/P1010123.JPG