For this week, let’s take a break to examine the hardware I’m using for my solar install.
The core bits of the hardware involved are ITEK 295SE panels, Sunny Boy inverters, and Midnite combiners/fuse boxes, in various configurations.
(Comments from Blogger)
2020-09-24 by Unknown
The black insulation in your boxes might be there in order to meet open air spacing requirements. Above 150 volts line to ground you need around 1" between conductors or between conductors and ground (depending on standards and other things). At the electrical products factory I work out of we place this material (factory people call it “fish paper”) under fuse blocks mounted on grounded steel barriers. Not because it is required by the fuse block manufacturer, but because there just isn’t enough clearance between the terminals and the steel at 480VAC.
hi, just came across your blog a few months back. Trying to catch up on older posts (maybe if I started at Part 1 this would be answered…)
I haven’t kept up on solar panel equipment, so I was surprised to see the tidbit “the benefit of some limited backup capacity if the grid is down”. Hmmm, what could that be? You don’t seem to mention that more, but I read about the Sunny Boy and found the SPS feature. Fantastic, I was looking for something like that ten years ago.
I’m shaky on how functional your system currently is … are you using the SPS feature? This seems like a great reason to have multiple inverters, just to get 2000W AC from each one. I glanced at the manual, didn’t seem like 240V was possible, so the water heater and pump are still problematic. Also, it seemed the SPS circuit doesn’t work until you flip a switch, so you couldn’t just leave the fridge & freezer plugged into it all the time?
Damn, was looking at pricing on the 3.8 version, under $1000. I’ll keep reading…
@JohnV - Welcome! Thank you for testing the signup flow! 
Honestly, my solar posts are a little bit scattered. They’ve been delayed by Blogger deciding to use an interface that doesn’t work, then Lent, so… eh. I may have missed some stuff, and the whole process was frustrating enough that I’ve failed to document all of it.
My system is currently fully operational, grid tied, and has exported around 700kWh this billing cycle (remains to see exactly what it works out to, somewhere in that range) after having pulled 3100kWh net since the system was put online back in the late fall (winter heat on electrons, plus basically all our transport miles).
I do have the SPS feature available, for about 5kW usable (each of the “big” arrays will hold 2kW sustained in most conditions, the small south facing array is closer to 1kW stable in the sun). It is single phase, 120V only, so you can’t run a split phase load on it. I have some solutions for this in the works, but haven’t posted anything about them yet.
And, yes, you need to flip the switch every time the sun comes up to enable the SPS feature. It requires the grid side being down (power outage or disconnect flipped) and then the switch. I’m not actually sure what happens if the switch is toggled while the grid is up - haven’t tried that. But it is an emergency supply, not a “leave it on and run grid down on whatever solar can provide” sort of thing.
If you’re doing roof mount, be aware that you can use SPS with optimizers now - you just have to provide 18V or so to the switch terminals. There’s a tech note on it, I’ve linked it somewhere else on this forum.
Easter is this weekend, so I’ll be resuming posts next weekend, with a few left on solar, and then plenty of other weird stuff I’ve been playing around with.