Small system to charge APC

[engineglue]

Hello.

I'd like to build a small solar panel setup to charge devices such as laptops, cell phones, and rechargeable batteries. I'd like to keep the number of components to a minimum. I currently own a few APC UPS'. Would it be possible to charge an APC with one 100W solar panel? If so, what equipment do I need. Would this work?

- 100W Mono Solar Panel
- 10A Voltage Regulator
- 375W Inverter
- 550VA UPS

I've attached an image to illustrate my idea.

I'm very new at this. My understanding of electronics tells me that this setup won't work because the APC draws 1440 Watts and the Inverter only outputs 375 Watts. However, I don't know if a 1440W inverter would solve the problem.

[engineglue]

I believe I may have answered my own question.

At peak, the panel can output 8A (perhaps closer to 3A on an average day). The APC draws 12A. Therefore, I believe I would need
four 100W solar panels, a solar controller and a 1500W inverter to charge the APC.

Considering the above, I believe it would be cheaper and less complicated to use only the voltage regulator to directly charge components and go without the APC. So, to charge a 19.5V/2.3A laptop, I can just set the voltage regulator output to 19.5V and plug it directly into the laptop. I could also make a 5V USB circuit to charge cellphones and other devices.

[Mike90250]

The APC UPS most likely has only a mod-sine inverter that has limited heat sinking, they are only made to run for 5-10 minutes to safely shut your computer down.

And, it's not enough power as you discovered, the inverter is not likely a efficient one.

[engineglue]

The APC UPS most likely has only a mod-sine inverter that has limited heat sinking, they are only made to run for 5-10 minutes to safely shut your computer down.

And, it's not enough power as you discovered, the inverter is not likely a efficient one.

Thank you. If I were to run multiple panels, I would get some deep cycle batteries and setup a charge system. I thought I could take advantage of the APC's I already happen to have, however, now I see that all that converting of electricity wouldn't be worth it.

[SunEagle]

Thank you. If I were to run multiple panels, I would get some deep cycle batteries and setup a charge system. I thought I could take advantage of the APC's I already happen to have, however, now I see that all that converting of electricity wouldn't be worth it.

You are correct that each time you go from DC to AC to DC and back there are losses. They add up and make a system very inefficient.

Better to use solar pv to directly charge a true "deep cycle" battery system with grid tie panels (200watt) and MPPT type charge controller. Then use a Pure Sine Wave inverter for AC loads that are electronic or have motors like refrigerators.

[Sunking]

I thought I could take advantage of the APC's I already happen to have, however, now I see that all that converting of electricity wouldn't be worth it.

You are right it is not worth it unless you have Mission Critical Application.

I do a lot of data center work and use very large scale UPS up to 2 MW. They use what is known as Dual Conversion technique. That is they take AC power, rectify it to DC battery, and then convert back to AC aka AC-DC-AC. What yu have is what is known as Stand By where the device is on AC all the time. When the power gets interrupted a small MSW inverter turns on and is ran by a small battery which has just enough capacity to allows you to shut down. When power returns the UPS has a small charger that recharges the battery in 24 hours. Not meant for 100% duty cycle.

You can make your own dual conversion Jame Bond UPS. You need an AC Battery Rectifier, a battery, and an inverter. Rectifier has to be sized to carry the full load of the inverter, plus enough to recharge the battery in 8 hours. Batteries are sized to carry the full load for X amount of time, and that is where it gets expensive.

[engineglue]

Better to use solar pv to directly charge a true "deep cycle" battery system with grid tie panels (200watt) and MPPT type charge controller.

I just looked up and read about MPPT. Makes sense. Thank you.