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My off grid camp in Maine is surrounded by trees with the ridge of roof directly across the path of the sun through the trees.. so.. I have to put panels on both sides of the peak enabling them each to get sun for 1/2 of the available daylight. So .. my question is... how electrically do I wire these panels to a charge controller... since half of them will be in the shade for 1/2 of each day.
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Last edited by sgtsaunders69; 09-03-2022, 05:08 PM. -
On the Winter Solstice [when th esuns arc is at its lowest] will sunlight even hit your North-facing slope?
I am also in Maine.
4400w, Midnite Classic 150 charge-controller. -
NStrench.jpg That is how my panels are set up. Wire the panels facing east
in parallel with the panels facing west. Each side will deliver
whatever energy it can at any time. Bruce RoeLast edited by bcroe; 09-03-2022, 07:53 PM.Comment
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Don't know.... we are only there in the summer... in fact.. heading home to Washington State today, September 3rd. We'll be back for the summer some time in late May.... so we really only need the panels to function from May to September while we and our grandkids and kids are there for the summer fun!Comment
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If the panels are set north and south, or any other arrangement,
identical panels or strings of panels still will work in parallel. Do
not put panels with different orientation in series, unless you are
using optimizers. Bruce RoeComment
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A bit off topic but FWIW, the specific output of Bruce's system - that is in terms of annual kWh production per installed STC kW - would be greater if all panels were oriented at the optimum orientation for annual production. Or, put another way, a smaller single array, optimally oriented in such a way that annual production per installed STC kW will produce the same or greater annual output.
Bruce and I have been at one another for years about that very thing. Without speaking (writing) for him, I believe he's acknowledged that his orientations do not lead to the most effective production, but apparently system cost optimization is not one of his project goals, but I certainly and wholeheartedly support his right to make his own choices.
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Ideally put in two smaller MPPT charge controllers feeding to the same battery bank. MPPT charge controllers do not work well with panels in different orientations, so you need to split up the strings into two that have the same relative orientation. BTW if you do not know what a MPPT charge controller is compared to a PWM controller time to get educated, MPTTs put out a lot more power from the same string but cost more money.
BTW, sad to say but at an unattended seasonal camp in rural Maine, solar panels and equipment is fair game to low lifes even out in the woods due to snowmobile traffic. There is a good cash market for the solar gear and buyers on Uncle Henry's, facebook and craigslist do not ask a lot of questions.
Panels should be engraved with identifying ID (like a street address) and mounted securely so that it takes time to remove them and preferably expensive stuff like charge controllers should be removed ad serial numbers recorded and preferably engraved with ID. Many camp owners have a locked gangbox or equivalent hidden under the floor that they lock up valuables in. If an extension ladder is needed to access the panels (even with 4 or 5 feet of snow on the ground, make sure the ladder is locked up preferably out of sight. This is not Maine specific issue but there are rural drug issues all over and seasonal camps sadly are regarded as easy picking. Just make sure your batteries are disconnected and fully charged prior to leaving them for the winter, preferably in a basement corner or a hole in the ground in a waterproof container so they can survive winter temps.Comment
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I'm sure Bruce is tired of explaining his unique orientations but he has limitations downstream that make that setup better that the optimum orientation. When you're already running a 2 to 1 DC to AC ratio his two string inverters are screaming for relief in the midday sun.Comment
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Is is there a charge controller that is capable of handling 2 or more arrays that are oriented differently and electrically separate?Comment
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That is right when wired in parallel. The shaded panels put out essentially
the same voltage at a smaller current, so they may be in parallel but not
series. This setup is good when you suffer a lot of clouds, or want to avoid
or are not allowed a much bigger inverter plant, or cannot optimally locate
panels.
That array has served very well for 9 years, details due to luck as much as
great planning. When the south facing performance fell flat on it face under
clouds here, this was thrown up in a month using panels already on hand,
in parallel with the south facing. It keeps the limited size inverter plant
very busy in all weather, avoiding doubling the plant while sacrificing some
panel capability. I did some measurements in 2016 to chose a more optimum
angle, but have not yet built the ground support needed for more than 2 of
my 12 strings.
Test3dir.jpg
This is the only way to get a daily power curve like this.
NScurJn17.jpg
Bruce RoeComment
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