adding solar panels, pt 2
{I actually started this yesterday but the terrible Wordpress block editor ate it}
The previous adding more solar post was top of mind yesterday, but the overall idea has been kicking around ever since my solar harvest fiasco in the Oregon NF. I was in a relatively open area but so surrounded by tall conifers that I was getting a few hours of direct sun a day.
Since then I’ve been mulling adding a couple portable panels (framed but not mounted on the vehicle). My thinking is that the panels can be used for:
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FOREST: the ability to move panels around would have resulted in another hour or so of sunlight capture
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TILT: the panels could be propped against the van for tilt, increasing yield in winter or at higher latitudes
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SHADE: in the unlikely situation I find myself somewhere hot I could park in shade and put panels in the sun.
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ABSORPTION: more panel should get me into Absorption earlier in the day, allowing for longer absorption duration
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LOANERS: I could move the panels over to a struggling neighbor
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EXPERIMENTS: there are some ideas I’d like to test with a couple panels and a small battery. Parallel v. Serial in certain conditions, for example.
The panels would increase the wattage from 570w to 770w when deployed, a 35% increase. Wouldn’t make much of a difference under poor insolation as we calculated yesterday.
So the idea was there, then the price of 100w poly panels at Home Depot and similar box stores has made it irresistable; 100w is $73 at HD. I picked the panel with the lowest Vmp as I’ll probably be running them on a shunt controller.
So I ordered the following and will pick up in Lake Havasu, AZ:
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2x 100w Grape Solar poly panels, Vmp 18.0v
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1x 15’ mc4 extension to be cut in half (connection to controller)
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2x mc4 parallel connectors, in case I need them
The converter’s primary use would be to step down voltage from the panels in case I run them in serial to minimize voltage drop. It has both current and voltage pots so it should also be possible to get the panels running somewhere near their Vmp. Or maybe I run them in parallel straight to the shunt.
I have a spare 10A shunt, spare 20A shunt, and a theoretically-in-use 10A mppt I could repurpose. It was installed as part of the DIY converter project but I haven’t been hooked up to shore power. My thinking is I’ll run both into the 20A shunt, using the buck if the panels are in serial. We’ll see.