Could I just keep adding panels to compensate for overcast skies?
I am learning the basics from a 75-watt solar panel from Harbor Freight and the charge controller that comes with the kit which looks like this:
I have other equipment too but for now am just focusing on this old kit.
These 2 pages say...
...that on overcast days, solar panels produce about 10-25% as much as on sunny days. I noticed that myself today - that even when it's raining my charge controller still says about 3-4 V. That's about a quarter of what it says on sunny days when it says 14 -15 V.
I tried searching online but couldn't find anything specifically answering this. Is there a way to compensate for cloudy conditions by adding panels until you have enough power? It seems like it should work as long as the panels aren't producing 0% of what they produce on sunny days.
I currently have a 75-watt panel. If I added panels in an array, in a series, would that work? Or would it perhaps need to be in parallel for some reason, instead of series? If I quadrupled my current wattage by adding 225 watts of similar panels (300 W total. 4 * 75 = 300) would that compensate for this 25%-of-normal output I'm experiencing due to cloudiness and allow me to charge up my stuff just as much as on sunny days?
I'm confused about some basics. If I wired the quadrupled array in a series to increase the volts to 14-15 V from 3-4 V then the system voltage would no longer be 12V. It would be a 48V system if I wired four 12V panels in a series. That means the charge controller automatically stops charging (according to the manual) at some cut-off point way above 11.1 V, which is the low-voltage cut-off point for a 12V system. For a 24V system, for example, the manual of one of my other charge controllers (not pictured) says the cut-off point would be 2 times 11.1 V which is 22.2 V. So, doing it that way wouldn't be making it any easier for me to get enough voltage on a cloudy day. Is there any way around that? Like perhaps by setting the charge controller to 12V somehow (if possible) despite it being a 48V system or does it automatically detect that it's a 48V system?
If you wired it in series instead would that work? I assume I need the charge controller to no longer say that only 3-4 V are coming through. Is that right? Does it absolutely have to say about 14-15V for me to go back to being able to charge my phone by plugging it into the USB plug that you see in that picture I linked to above on the Thunderbolt charge controller?
Right now, I only want to power (by usb cords) a phone, hotspot, and a 20,000 mAh power bank. The batteries of these small devices say "3.8 V lithium ion..." Why do I need the charge controller to say 14-15 V? I'm not charging a 12V battery so I was hoping that even with only 4 V coming through on the charge controller, that it'd still be enough to charge my phone. When I plug in when it's saying 4 V, however, it doesn't charge. The phone will only charge when it says about 14-15 V. When it says anything below that, it won't charge my phone.
Thank you for any guidance.
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