My house was added on by some incompetent home remodeler back in the 60’s or 70’s before any significant building codes were being enforced. The result is a funky mishmash of pitched roofs that looks like a shotgun shack version of the Winchester Mystery House. To give you an example of the do-it-yourselfer’s craftsmanship, when I remodeled last, I found sofa cushions in the walls used as insulation and a part of a gate with hinges used as a roof panel. I mean this guy was low budget!
Any how, my real point is that my roof is leaking and I’m thinking of replacing the trusses in order to align all the roofs under a single pitch. This will also allow me to add a microscopic bathroom to the “Master” bedroom.
I’m not going to add solar photovoltaic panels just now, but I’d like to design for future installation if I so desire. Does anyone know what the optimal pitch of the roof should be? I’m at about 34.4°N latitude and the roof faces southwest.
The main thing you want is for the sun to hit the panels straight on. In spring and fall at the equinox this will be the latitude you are in. In the winter the sun gets lower and the angle will have to be greater. In the summer the sun is higher and the angle will have to be less.
I don’t have a cite handy, but the basic rule of thumb is that the tilt angle should equal the latitude, and the axial placement should be perpendicular to north-south, plus or minus 10 degrees.
I also recall being surprised that deviation from optimum does not hurt performance too much. A lot of high-performance buildings (such as this one) are putting PV on vertical surfaces (90 degree tilt angle).