Just re-read the question, and placing heat tape above the panels would cast shade on the cells. Full shade over even a single cell can dramatically reduce output for the full panel. It's confusing, but basically all the cells operate like a chain and are only as good as the weakest link.
Placing tape below the panels wouldn't help much, since they're offset from the roof with a bit of an air gap. The heat might not radiate far enough to help.
That said, if you insisted on them and could work out getting the heat applied correctly, it would help. A bit. But you have to amortize the cost of installing and maintaining the heat tape against production losses. Last month we had a snow storm plus inversion and I had zero production on the 19th - 25th. Given the cloud cover, at best I could have averaged 15 kWh per day. So, $1.50 * 7 = $10.50. Which sounds like it'd be a no-brainer: get the heat tape! But net metering means that excess production gives you credits that roll over. If your net metering credits are close to zero in the winter on a regular basis it might be worth considering. Or you could add another panel to the array and build up additional credits for the winter months.
tynman3 karma
Just re-read the question, and placing heat tape above the panels would cast shade on the cells. Full shade over even a single cell can dramatically reduce output for the full panel. It's confusing, but basically all the cells operate like a chain and are only as good as the weakest link.
Placing tape below the panels wouldn't help much, since they're offset from the roof with a bit of an air gap. The heat might not radiate far enough to help.
That said, if you insisted on them and could work out getting the heat applied correctly, it would help. A bit. But you have to amortize the cost of installing and maintaining the heat tape against production losses. Last month we had a snow storm plus inversion and I had zero production on the 19th - 25th. Given the cloud cover, at best I could have averaged 15 kWh per day. So, $1.50 * 7 = $10.50. Which sounds like it'd be a no-brainer: get the heat tape! But net metering means that excess production gives you credits that roll over. If your net metering credits are close to zero in the winter on a regular basis it might be worth considering. Or you could add another panel to the array and build up additional credits for the winter months.
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