In the heyday of Northern Colorado’s solar industry, Charlie Bacorn’s company installed an average of four solar systems a day. That was in the early 1980s. He has installed only four systems so far this year.

So, when Bacorn says “sales are down,” you know he’s understating matters.

Indeed, solar-energy companies here and nationwide are in the midst of one of the worst downturns in their industry, beset by excess manufacturing capacity, which has led to oversupply, a nearly 50 percent decline in wholesale prices and intense competition from the Chinese.

U.S. manufacturers of solar panels brought a trade case against their Chinese rivals last year, claiming the Chinese government had improperly subsidized them, allowing those companies to sell at prices below the cost of production. In response, Congress this spring imposed substantial tariffs on the Chinese firms.

But it hasn’t been enough.

Shyam Mehta, a senior analyst at GTM Research in Boston, doesn’t think the situation will improve any time soon in what he describes as an “overcrowded and cutthroat PV landscape.”

“Over the past year and a half, the photo-voltaic