Recent content by hex4def6

Maybe... But that could also be dealt with using some sort of over temperature foldback. Reduce the available maximum power generation ability when the device gets hotter than (say) 80 degC. Continue to derate to 0% when it reaches (say) 100 degC. Throw some fan speed control in there, and...

Hmm. That makes sense to me. If you're not relying on the MCU + algo for OCP, then I agree. Even something simple like a shunt resistor and comparator controlling the gates would be pretty darn quick. But then, where does the idea these limits come from? Is it purely from an abundance of caution?

For sure. That brings up another question of mine -- I've noticed a lot of installs use those "solar skirts". I question how good they are for panel efficiency. Seems like they would severely cut down on air circulation.

I agree its reducing the actual energy as well - that 20% panel efficiency is stopping that energy from becoming heat. That's worth 200W/sq meter alone, which is substantial! I think what also would help is that the back of the solar panel is white (PVF is 0.8-0.9), whereas shingles are...

First, I think you're assuming a sealed attic -- wouldn't that boundary layer still be hotter than the bulk ambient, and thus want to move up (to the ridge vent)? This would result in a convective movement, increasing effective thermal conductivity / transfer to the air. Regardless, however...

So I've seen some debate / discussion on why there are practical limits on overpaneling. I've seen SolarEdge recommend 135% / 150% / 175% depending on model, for example. What I haven't found is "why" they have these limits, but I have some theories. They are concerned about the inverter...

Just wanted to add: Got my AHJ signoff today, passed on the first try. He was pretty complimentary about, which was good for the ego :p It's always good to be a good ambassador for DIYers -- I feel like the pros often have a level of contempt for us. It's good to change their mind, so they...

I was assuming heat flow into the ambient air in the attic which I guestimated at ~80degF right now. In both cases that would be the heat sink. The outside roof temperature I think is immaterial (eg, the temperature of the shingles themselves). I definitely should measure that properly, and I...

Thanks! Unfortunately I've not taken any videos with the panels, but here's one with it empty: This version could have had a shorter link between the sled and pulley, to allow it to got higher up on the rails. I was helping my dad with solar on his house, and he made a quick and dirty...

Here's a thermal camera video in my attic showing the difference in temperature between underneath the panels vs exposed deck.

One interesting side effect of mounting solar panels on the roof has been looking at attic temperatures. Measuring the underside of the deck it seems like there's a pretty clear difference between underneath the panels, and roof that's exposed to the sun. Just measuring right now (outside...

(Cross posted on /r/diysolar) Just thought I'd present my project. This is in California, Bay Area, on PG&E (boo, hiss). It's 30x 315w Canadian Solar panels (9.45kW), on Ironridge XR10 rails, with their HUG quickmount feet. I'm using IQ8+ for these panels, in three sets of 10. The Q-cables are...

I've gone through the IQ8 commissioning training (had to do that to bring up the current system), and I'm about halfway through the power stuff (mainly for fun). In theory, you if you don't care about backup power, you can run their IQ Battery 5P without the system controller. But, you'd lose...

I'm guessing that would come down to the ATS-- "make before break" vs "break before make". It would be a bit of a nuisance to have the latter, but not insurmountable.

Yeah, I'm pretty sure they consider DC Inverter increases or CEC AC increases to be NEM deal breakers. Hence the "off-grid" addition idea. What I hadn't realized (based on the NGOM comment), (which brought up this article...