Pictures of two installs with different roof pitches.
It snowed here in Colorado over the weekend and I thought I would take a few pictures of how snow will stay on solar panels depending on the angle they are mounted.
These two solar installs are right next to each other and use the exact same panels, the picture above has a steeper roof than the one below.
I don’t know the exact angles of the two roofs (perhaps I can call the architect) but the bottom one I would say is 5-7 degrees less tilt. Just a guess.
Update: John Shaw of Bella Energy in Louisville Colorado (an expert in solar) contacted via email and with his permission I am publishing what he wrote me, because it is really good stuff on this topic:
The best angle to keep snow off is 90…. LOL, JK, but seriously, you don’t set them to keep snow off, you set them either for max annual performance or set them at whatever your roof angle is – if you don’t like to pay extra for tilted panels or don’t like the look of titled panels.
I can tell you that the added cost of tilting panels on a roof (say from 20 to 40deg (optimal for PV in CO)) almost never pays off since 20 deg. pitch is 96% efficient. Oh, by the way, “optimal” is based on 15 years of hourly measurements by NREL in Boulder and it takes snow, dust, leaves, pollen into account.
A day off-line for a 5kw system (south, 20 deg. pitch) due to snow coverage will amount to about a loss of $1.80 in power vs. a clear day. Over the year, it will still get what it oughta and if not it will make up for it next year… A 40 deg. 5kw facing south would lose $2.09. At $0.29/day gain (Oct. example) due to optimum pitch you can see that it will take a whole lot of snowy days to pay off having added >$1000 to the cost of the system for tilting them to a better pitch – whether the reason is for snow shedding or optimal production angle.
It is also therefore not worth climbing up and pushing snow off – break your back to save $2…
http://www.roofrake.com sells a soft headed roofrake that will not hurt solar panels and can push or pull snow off of them. They offer a ton of telescoping poles to reach lengths of 2-24 plus segmented poles to reach up to 41 feet.