Timed solar array switching

Bluetti needs to make a time programmable switcher connecting to multiple solar arrays to take advantage of different panel locations and arrangements at different times of day. My house location and position robs me of half a day of sun, but if I had 2 panel arrays that would automatically switch for morning and pre noon I could maximize solar input cheaper than a sun tracking system. This would also strengthen the system with panel redundancy.

I don’t believe Bluetti or any solar panel vendor has such a device. I can suggest getting two Christmas light timers and modify the internal switches to open and close for each solar array instead of the original 120 VAC lights. Since these timers are designed for one rotation every 24 hours, and you can set the on and off times, they can solve your need and cost less too. Just get a handyman to modify them.

Instead of switching between 2 sets of panels, can you wire both sets in parallel and connect both in that way? Assuming they are the same voltage. As long as one set is not in complete shade and can still “see the sky”, it would produce close to the same voltage even when not in full sun. So the parallel voltage won’t drop much and you get the benefit of total current no matter which way the sun is shinning.

If you connect both sets in parallel, the set getting the least Sun will pull down the volage outputs. You can prevent that if you insert a diode in series for each set, so the set with lesser Sun will be isolated until it generates more voltage output than the other set. You can lose about 7 watts (10 A X 0.7 V forward voltage drop per diode).

True, but the depression in voltage might be a made up with the added current and ease of use. It depends how deep the shade is. Generally, the current potential drops with shade a lot faster than voltage. A typical data sheet for a full sized panel suggest that even at 20% sun, current potential is close about 20% but voltage is still nearly the same. Now, if it is really shaded and gets no view of the sky, then that’s a different story. If wiring is easy, you can give it a try and measure the results.

Interesting. This would also allow for overlap when the time is optimal for both panel arrays.

In my situation, the panel array (I don’t have 2 yet) would be shaded by the house until the sun comes around about 11:00 - 11:30 am, but it would face the sky. In my current testing, it drips about 5 watts periodically until the sun hits the panels. I’m disappointed in my system though because I can’t even expect my AC200P to fully charge in a single day cycle. To be fair, my panels are not optimally positioned, but since I planed to mount them on a van roof. I figured it was good to test this way since flat on a van roof isn’t optimally placed either. I’m only getting a little over 25% charge with 2 24V 210Watt panels connected in series from a whole day of perfectly blue sky. I expected way more than that. Even with the morning hours I’m losing, I could only expect about another 20% charge.

I must be doing something wrong.

2x24v 210W panel should make around 300w on a good sunny day. With no other loads, it should make the equivalent of 5hr x 300w = 1500wh a day. Now charging is maybe 80% efficient so say 1200wh, about 60% of an AC200p. If you are only getting 20% charge for an whole day from that, something is wrong.

Are the panels in the sun the whole day?
Are there loads on the AC200P?
Is the AC or DC output turned on? They can drain power even if no loads are connected.
When panels connected, what is the power input meter say?

I noticed my 120W 18v panels would still produce around 10-15W in the shade with almost the full voltage as long as it can see the sky. The scattered light still has energy. When it is in the max full sun, it will make 90W or so.

I get 5-10 watts in shade and I don’t get full sun till some time between 11 - 11:30 am. I also have a tree line that interferes by 3pm but it seems that any angle of the sun drops watts significantly. I saw 26-30 watts after 3pm. I knew alignment was important but I didn’t think it would kill that much power. Also, my tree line has no leaves this time of year.
I have seen as much as 380 watts but that doesn’t last for hours. Seems the panels have to point exactly at the sun. Temps are around 40 degrees right now, and I thought power increased in cooler temperatures and decreased in hotter temps.

Turns out shade is the power killer. Any shade on cells no matter how small kills output. With less than 1 square footage of shade on one panel out of two run in series, I had 70 watts of power angled at 36 degrees at 12:45 pm. Laying the panels flat with absolutely no shade immediately jumped the power to 240 watts. That’s a huge difference. I can’t wait to see what a full day charges now.

I guess mounted on a van roof will work after all.

Oh yeah, due to how the panels are laid out, even a panel 10% shades may cut power by 80%. And if that is in series, it lowers the current, forcing the other panel to lower its current too. Some panels have various bypass diodes that makes this a little bit less bad.

Instesd of in series, put both in parallel with a diode on each, and the set with shade will not pull down the power output of the other with more Sun.

My concern there is that the panels could fall under voltage in the heat of the sun. But I’m not sure what that limit is now. I thought the AC200P required 35v minimum input, but I just experimented with an unregulated DC output from a generator and was able to register 18 watts of charge with 30v input on the PV connection.
Based on the panel specs, the voltage drops under 35v between 120 -130 degrees Fahrenheit. I’ve read panels can reach surface temps of 149 in direct sunlight during the summer.