Solar UPS controller/automatic transfer switch

Power plant in toolbox size: the new UNplug power generator can be carried around easily. This is the fully functional prototype – currently only the H4 solar connectors are still on order. I just got the green side panels but need to find the right screws first.

circuit - Solar UPS controller automatic transfer switch

The new design includes:

1500W pure sine wave inverter, sealed lead acid or lithium type batteries in a sturdy metal case with a total weight of 77 pounds. In full configuration this power generator is able to charge an electric vehicle via a level 1 charger! (with enough solar panels attached)

Capacity of the batteries are 0.8 – 1.2 kWh depending on the type. This is enough energy to power your fridge during the night.

I am using a separate power supply now because creating you own stable power supply for 24VDC from 120-240VAC is not easy or cheap. I am also having my own PWM charger for the solar panels (2 rows of mosfets) now. The inverter in this version will need to be one with a remote power-on function. I am also down to 6 cable lugs to make things lighter.

New and noteworthy items:

  • 30A, 120/240VAC heavy duty relay
  • external 40W switching power supply to charge the battery and power the unit at night
  • 50A, 32V solar PWM charge controller built-in

[UPDATE] Kickstarter campaign, please click here for the project page.

[Original text]

It all started during a stormy winter in 2011 when my power was out for 4 days. I was thinking: if I only had some independent power source available. Maybe I would not have lost all my food in the fridge…


I have developed a small ‘box’ that let you use solar energy in a very small scale. It powers just a few household items that run 24/7 like the refrigerator, internet modem, security system, laptop, etc.

It is modular, scalable, moveable and it connects any inverter, battery, charge controller, solar panel up to 1500W continuous power. It has wifi and hooks into Home Automation. It could also be labeled as Automatic Transfer Switch.

Read More:  Solar UPS controller/automatic transfer switch

This Post / Project can also be found using search terms:

  • arduino ups controller
  • Solar UPS controller
  • arduino transfer switch
  • automatic transfer switch esp32

Leave a Comment

= 5 + 1

(Spamcheck Enabled)

Read previous post:
With the ID3LA RFID module it´s possible to read a tag up to 30cm
With the ID3LA RFID module it´s possible to read a tag up to 30cm

As we know, RFID module range is expressively depending on a size and shape of the RFID antenna (coil). That´s...

Scroll to top