Here's my experience using the three tools that I've come across.
Avalanche - In theory this should be the best tool out there for clearing the panels. Based on using it, it seems to be a wonder if I ever needed to remove snow from my roof but it can be a pain with the PV unless you've got a lot of snow to remove. It doesn't remove too close to the module, it gets down to about 1/4 to 1/2" in most areas except you run into a serious issue over the mounting hardware for the panels, you can't get too close going over that, not to mention the fact that you are pulling a plastic sheet over metal hardware. I've got holes in my avalanche. ..because of this, I only use it when I've got over a foot on the panels.
Backwards-facing shovel(aka plastic roof rake) - This works reasonably well except it seems to get down to 1/8 to 1/4" depending on the type of snow you are removing, it also takes multiple passes to catch what was left over. It also snags on the seams between the panels and on the hardware as well, which usually involves more passes.
Which leads me to my most commonly used tool
: Drum roll :
The widest broom I could find with the stiffest (without scratching) bristles I could get with a lightweight handle. I'm still working out the plan for a better pole system, so far I've used two 10 foot EMT conduit sections added to the end of the initial metal broom pole and that worked out but was super heavy. Then I moved on to wooden dowels that fit inside EMT conduit connectors which lightened things up and made things less wobbly at the same time. It's still not perfect because there is some extra space inside the EMT connectors to not have whole pole sag a little but it works good enough until I think of a better system. Commercial extendable poles are too short, too flimsy, and too expensive. I think I might buy another extension to my plastic snow rake and try to jerry rig the broom handle to where the rake head is normally mounted.
What the broom allows is to get very close, the bristles can pull over uneven areas such as seams of the panels and will glide over mounting hardware. It also lets you slide over icy chunks that are sometimes present and allow you to get the closest you can, which with time, a black panel, and the sun, will melt that stuff off sooner.
Pro tip
I find that I must be diligent with timing the clearing of fresh snowfall. If I get it first thing in the morning, the panels are cold and the snow doesn't readily slide down the panels as I sweep it off. If I get it between 2 and 3pm when the sun is strong, usually the panels are warm enough with the light that gets through the snow to the black panel to where the snow will slide off as I'm sweeping it down, which helps get the last few dregs of snow and usually will also aid in melting the rest off with the remaining sun and if anything is there on sundown, it will usually be completely cleared by the next day.
I can't imagine clearing snow this often or to the extent that I do if I had a single MPPT on my system though. In that case, the worst panel dictates the output of the whole system. I have a SolarEdge system with one MPPT on each panel and I've had one module producing 150 watts(it's winter without full sun) while another was producing almost nothing because of uneven snow clearing. This allows me to clear as much of the snow off as I can but still not worry enough to try anything crazy to get the very last bit.
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