In the past month, Petaluma-based Enphase Energy stock soared 27 percent from $1.50 on Valentine’s Day to $1.90 a share on Feb. 27. Then the stock plunged 40 percent to $1.14 on March 9. This week Enphase edged back up 19 percent to $1.36 in recent trading.

North Bay Business Journal published an in-depth story on Enphase Energy on Feb. 13. The company makes micro-inverters that attach to individual solar panels to change direct current into alternating current — the kind used in households and businesses for lighting, computing and manufacturing.

Enphase, which had a peak stock price near $17 a share in Sept. 2014, struggles in a solar-energy market flooded with cheap panels made in Asia. On Feb. 28 the company reported revenue of $90.6 million for the fourth quarter of 2016, disappointing some analysts and up just 2 percent from third-quarter revenue. In its fourth quarter, Enphase sold 815,000 micro-inverters and lost $13.2 million.

Total revenue for 2016 was $323 million on shipments of 3.1 million micro-inverters.

At the end of January, Enphase Energy laid off nearly 18 percent of its workforce, including 75 full-time employees plus another dozen contractors. There were hints of investor confidence, as Enphase reported a $5 million investment by John Doerr, chairman of venture-capital giant Kleiner Perkins Caulfield & Byers, and another $5 million by Thurman John Rodgers, former CEO of Cypress Semiconductor.

“They didn’t make it conditional on the layoff,” said Paul Nahi, CEO of Enphase, of the $10 million from Rodgers and Doerr, who got their shares at a discount — about $1. But “it was very important for them that we achieve profitability as quickly as possible. That was one of the elements.”

In August 2016, Enphase launched measures to survive near-term challenges then reenergize the company long term. It began shipping batteries to solar-array customers in Australia and New Zealand as a new trickle of revenue to augment sales of micro-inverters.

Enphase Enphase’s new storage units, touted as “AC batteries,” rely on lithium iron phosphate cells, a battery technology with safer chemistry than many. Like other batteries, they store electricity as direct current. The 1.2 kilowatt-hour batteries sell for about $2,200, weigh 53 pounds, and can be discharged up to about 7,300 cycles and down to zero percent of capacity without damage. Modular design allows expansion to optimize energy use in relation to system cost.

Enphase expects first-quarter 2017 revenue at $60 million to $65 million.

James Dunn covers technology, biotech, law, the food industry, and banking and finance. Reach him at: or 707-521-4257