Onyx Photo-voltaic Glass, High Voltage - Low Power

[JPearson]

Dear Solar Panel Talk,

I purchased a non-traditional solar panel for a small hobby setup in my backyard. I wanted to have it isolated from the grid and the house and simply tied into a battery and a couple of small loads.

I am finding that this is much more complex than I had imagined. The solar panel is 190 Voc, 0.79 Amp nominal, 104 W nominal peak power. I have a 12V battery I'd like to link this up with.

It appears there aren't easily accessible off-the-shelf charge controllers that can handle such an application. I have spoken to Radio Shack and some professional electricians and engineers with no luck finding out how to go about linking all of this together. The electrician suggested a forum. I am interested in the easiest/cheapest approach, even if it results in significant losses in efficiency. I would imagine it could just be a matter of reducing the voltage from say 190V to 40V and purchasing a typical 40V charge controller designed for a 12V battery, but without a strong electrical background, even if that approach is very simple I do not know how to go about doing it. Perhaps something with inverters? I could convert back to DC for the battery and the DC loads. That may sound silly, but if it ends up being the cheaper option, it would be preferred.

I can follow instructions, so even if the solution is something that needs to be hand built I can work with that,

Thanks!
Jeremy

[littleharbor]

You'd be better off starting fresh with a basic 12 volt panel and an inexpensive PWM charge controller.

[Mike90250]

200V charge controllers start at $500. Abandon the panel, or re-home it on craigslist.

And start over with a panel with about 21Volts open circuit, that will work with any of the plethora of 10A $20 PWM charge controllers

[woswasi]

there are some MPPT charge controllers from EPEVER that can handle up to 200V, i.e.:

Tracer 5420AN (50A @ 200V)
Tracer 6420AN (60A @ 200V)

according to offers on ebay, the 5420AN is about 220 USD.

kind of overkill for a 100W panel, but lot of spare power for future extensions.

[littleharbor]

there are some MPPT charge controllers from EPEVER that can handle up to 200V, i.e.:

Tracer 5420AN (50A @ 200V)
Tracer 6420AN (60A @ 200V)

according to offers on ebay, the 5420AN is about 220 USD.

kind of overkill for a 100W panel, but lot of spare power for future extensions.

For that matter they have 80 and 100 amp 200 Voc. controllers too.

https://www.ebay.com/itm/100A-80A-60A-50A-Epever-MPPT-Solar-Charge-Controller-12V-24V-36V-48V-Tracer-AN/143227986907?hash=item21590da3db:m:m-RGBA---nqKd0ihfx14sqQ

[Tecnodave]

A 190 volt panel will go over the 200 volt rating of that controller on a freezing morning, destroying it, a 250 volt controller will be required

[PNPmacnab]

Most electronic wall warts (no heavy transformers) will work directly off DC of that voltage so you can charge cell phones and many laptops. Go to ebay a 12V 10A DC supply for about $11 shipped from US included. It will only go up to 13.5V without modification. It will throw the panel voltage into a death spiral at low voltage but can be modified. I use a system like this with a $5 pwm controller. And unfortunately, no one can follow simple instructions. All this is at your own risk.

[JPearson]

PNPmacnab, thanks for the tip. I bought a $20 PWM 10A controller on Amazon (<55V input). I found that I could drop the voltage prior to the controller by linking some light bulbs in series. Although if I took those out and only had the controller in the loop, I'm inclined to think that the the voltage would likely still never get up above 55 V since the short-circuit current of the panel is only 0.97 A and the resistance of the controller is probably relatively small. I'd like to still get as much power out of the panel as I can. Perhaps I could but a second controller in series and add a second battery. Any thoughts? Could you elaborate on what you meant by the death spiral at low voltage?

[PNPmacnab]

You have been lucky so far, maybe. Typical FET in these charge controllers is 55V. At about 63V the FET will start to conduct by itself acting as a zener. In other words the device will be dissipating 60V X .5A or 30W that you have no control of and that can lead to failure. Light bulbs don't help very much. It may be already destroyed and not even know it. I told you a switching power supply can be used on this panel. Under very light load that could produce 12V of some use to you. A panel is a current device and that current varies with light intensity. Intensity does not control voltage. That changes with how much load is placed on the panel. Switching supplies substitute voltage for current. s you try to draw more current the panel drops even more. With that lower voltage it tries to draw even more current. It keeps spiraling down that way. If you had bought the power supply it probably could have supplied 30W @12V reliably most of the day without overloading the panel.

[JPearson]

Thanks PNPmacnab, I just purchased a 12V 10A DC power supply. I just didn't fully understand your original post at first, and came back to it later, and it made sense. So if I use the power supply, I assume I would still want to hook it up to the charge controller rather than directly to the battery, or can it go directly to the battery and leave the charge controller out?

[PNPmacnab]

You can run 12V devices off this power supply, but you can never charge a battery without it being modified. I think this supply is adjustable up to about 13.1V. A flooded battery takes 13.8V just to get to float and higher to get to full charge. It is in range for lithium cells. The range can be altered by changing a resistor if you are up to that.