Ever since photovoltaic cells started popping up on pocket calculators and building roofs a few decades ago, solar power has faced a key drawback: It’s a nice technology, but there’s simply not enough of it to make a difference. Right now, it’s facing the opposite difficulty.

The tidal wave of investment panels has swelled to the point that it is threatening to overwhelm the global industry. Amid the onslaught of cheap Chinese-made modules, overseas manufacturers have either walled themselves off behind tariff barriers (as in India and the US) or resigned themselves to extinction, as in Europe. Now, even the Chinese companies blamed for the current glut are panicking.