How long would you go without your refrigerator? How about your stove, lights, coffee maker, microwave, television? In May 2022, Joshua Spodek disconnected his Greenwich Village apartment from the electrical grid to see if he could live unplugged for a year.

Two and a half years later, he is still off the grid, and has a new book that he bills, in its understated subtitle, as a guide to “Solving All (Yes, All) Our Environmental Problems.”

Going off the grid has long been an appealing fantasy: Plant some solar panels in your backyard next to the hot tub and the organic vegetable garden, and let the energy flow.

Doing it in a studio apartment in New York City is something different.

Mr. Spodek, 53, an executive coach and former adjunct professor of leadership and entrepreneurship at New York University, is easy enough to spot in the neighborhood. On a sunny October afternoon in Washington Square Park, a few blocks from his apartment, he was the guy with four solar panels spread out on the lawn behind him.

Nearly every day for the past 30 months, Mr. Spodek has lugged solar panels and a 17-pound battery up and down 11 flights of stairs to his roof to charge them. (Taking the elevator would be cheating, electricity-wise.) With four hours of sunshine, the setup provides enough juice to power his laptop, cellphone and Instant Pot pressure cooker for the day. The gear cost him about $700 on Craigslist.