Photo by Tschernjawski Sergej on Unsplash

How a $100 Solar System Charges all my Electronics for Free

One foldable solar panel the size of a sheet of paper charges my iPhone, iPad, Chromebook, and VR.

C.C. Francis
2 min readAug 17, 2022


When people think of home solar, they imagine spending $15,000–25,000 for panels — another $10,000+ on a Tesla Powerwall or the like.

For $100, my iPhone, iPad, Chromebook, and Quest 2 all charge for free.

A foldable 21W solar panel sits in my driveway right now, charging two 25,000 mAh batteries. In two days, both batteries will be full.

  • The 21W panel (about the size of an sheet of paper, folded) was $40.
  • The Li-ion batteries (each about the size of an iPhone) were $30 each.

Both are from Amazon. Both use USB-C for input and output.

In two days, I’ll conservatively net 50,000 mAh (about 250 Wh of power at 5V). That’s 25,000 mAh/day.

Consider the battery capacities of personal electronics:

Combined, these gadgets store 21,445 mAh.

One 21W solar cell adds more power every day than all of my devices combined can store.

Portable batteries rapidly charge from USB-C output. I don’t have to worry about plugging anything into a wall. I don’t worry about whether my devices are charged, and I don’t feel guilty about charging them.

It’s one of the best $100 I ever spent.



C.C. Francis

Author | Attorney (CA) | Stanford ’11