These solar cells turned brown from a solar concentrator experiment.

This is probably what would happen if you put a lens in front of each cell for a while.

Even the tab wires turned brown.

At least that's what it looks like they did. I didn't see the experiment setup. I got these cheap at a swapmeet years ago and they are labeled "low output" but they still give me power every day.

Each one is 6V and the last one on the right was added to bring them up to a good voltage, I am using them on a 24V system. I get about 40W into the grid from the set on a good day.

The front is what looks like normal clear glass, nothing special and the backs are just like any other panel with a white plastic backing material.

The interesting thing about these panels is that they react to clouds very well, I get almost full power on partly cloudy days when the other "normal" ones go lower.

They also start to put out more power earlier than the others (off angle) and I am not sure why. They may be made of a special type of crystal.

In the closeup pic you can see how the cells used to be normal blue looking cells.

I don't know anything else about these, there is no information sticker on who made them and the guy who was selling them only said they were part of a concentrator experiment.