I Collect Pulleys

I don't know what type of wind you get.

If you add bricks for ballast you would add that weight to your snow load, but the panels would also act as sails. Here snow load is nothing. Literally. In all my life I have never seen snow that didn't melt instantly when it hit here in the desert. I have seen snow only a few times, but it just left little wet spots. My concern was wind load for a substantial solar array could be significant. Here we get dust storms with sustained winds in the 45-60 mph range and gusts up to 80 mph. For a dink little dish on a flat roof potentially (almost always) behind a parapet wall its not a big deal, and if it moves a little its an easy fix. More bricks. Sure, but that means more weight, and that weight is added to your snow load.

Here wind and seismic zone are our issues.

I don't know what type of wind you get.

If you add bricks for ballast you would add that weight to your snow load, but the panels would also act as sails. Here snow load is nothing. Literally. In all my life I have never seen snow that didn't melt instantly when it hit here in the desert. I have seen snow only a few times, but it just left little wet spots. My concern was wind load for a substantial solar array could be significant. Here we get dust storms with sustained winds in the 45-60 mph range and gusts up to 80 mph. For a dink little dish on a flat roof potentially (almost always) behind a parapet wall its not a big deal, and if it moves a little its an easy fix. More bricks. Sure, but that means more weight, and that weight is added to your snow load.

Here wind and seismic zone are our issues.

Bob La Londe

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I'm in a shallow valley that runs at an angle to the prevailing wind, so it mostly affects the tree tops. I just had five of them taken down because they could have fallen on the roof, cut up the firewood and am stacking the lumber logs to cover for the winter. That 16' long gantry hoist I built is getting a workout, plus a few mods.

My roof solar array isn't "substantial" and will stay up there if the wind shifts it, because it hangs from the safety eyes. 300W will recharge the battery for the freezer in up to moderate overcast or light rain and I have another 200W to add at a December sun angle after finishing the more critical winter prep tasks. Their price has fallen below $0.70 per Watt, and these tested at 91% of rating from low November sun near 42 North. By mid February I've measured full rated power from older panels. They work much better at lower temperature, enough that the full sun power production is nearly constant from February through November.

This is a DC version of the Wattmeter I mentioned, and used with a large rheostat to test panel maximum power, and see if an MPPT controller would be worth the extra cost, vs adding another panel to a much cheaper PWM controller. I agree with the advice that PWM is better below 500W.