06-07-2018, 11:38 AM
Drilling actual round holes, instead of triangular, can be done more easily with stepped drill bits.
![[Image: image_11761.jpg]](https://shop.harborfreight.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/i/m/image_11761.jpg)
I have two sets of harbor freight specials and they are holding up remarkably well and get a lot of use.
I will still use one of the center punches and drill a small pilot hole on precision applications, but If I can used a stepped drill but on the application, it is used.
One thing aout the curved surfaces of vehicle roofs, and flat panels, is that even slight breezes will evacuate a lot of air inbetween the panel and roof due to that curve, as the far side creates a low pressure inbetween which the high pressure side tries to fill.
Flat panels over a flat surface such as a stick and brick roof, will have much less airflow under them and output should significantly increase with more room under them.
I'd have no fear of loss of output from plat panels mounted in close proximity to a curved roof. I would have mounted my Kyocera panel even closer, but its junction box was the biggest limiting factor.
One thing which would help panels stay cooler, would be if the underside were a dark color. It would radiate more heat from higher emissivity of dark colors. Though it would radiate this extra heat to vehicle roof in our applications, on a stick and brick this should not be an issue whatsoever, and this radiated heat would make the panels slightly cooler, and thus output more juice, but No panels come with dark undersides, that I know of.
So either nobody has ever though of applyng this scientific fact of emissivity to solar panel reduction of heat, or it simply make so little difference that a light or dark undersiders make no difference in real world usage.
It would be interesting to do an actual side by side temperature measurement of the same panel's output, one with 1 inch spacers and one with 2 inch.
I hypothesise any difference, would be small, and could likely be made up for in thicker wire to solar controller.
I'll not be performing the test.
I have two sets of harbor freight specials and they are holding up remarkably well and get a lot of use.
I will still use one of the center punches and drill a small pilot hole on precision applications, but If I can used a stepped drill but on the application, it is used.
One thing aout the curved surfaces of vehicle roofs, and flat panels, is that even slight breezes will evacuate a lot of air inbetween the panel and roof due to that curve, as the far side creates a low pressure inbetween which the high pressure side tries to fill.
Flat panels over a flat surface such as a stick and brick roof, will have much less airflow under them and output should significantly increase with more room under them.
I'd have no fear of loss of output from plat panels mounted in close proximity to a curved roof. I would have mounted my Kyocera panel even closer, but its junction box was the biggest limiting factor.
One thing which would help panels stay cooler, would be if the underside were a dark color. It would radiate more heat from higher emissivity of dark colors. Though it would radiate this extra heat to vehicle roof in our applications, on a stick and brick this should not be an issue whatsoever, and this radiated heat would make the panels slightly cooler, and thus output more juice, but No panels come with dark undersides, that I know of.
So either nobody has ever though of applyng this scientific fact of emissivity to solar panel reduction of heat, or it simply make so little difference that a light or dark undersiders make no difference in real world usage.
It would be interesting to do an actual side by side temperature measurement of the same panel's output, one with 1 inch spacers and one with 2 inch.
I hypothesise any difference, would be small, and could likely be made up for in thicker wire to solar controller.
I'll not be performing the test.
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