How has Solar Efficiency Changed Over the Years?

Is now the time to buy a solar panel system, or is the rate of increase of solar efficiency going up fast and I should wait.

I want to know how solar panel efficiency has changed. If you are like me watching your two year old computer become antiquated after spending $1,000 on it is not fun, I don’t want to see this happen to a solar system I might pay $35K for.

Solar panel efficiency is the transfer rate from the sun’s energy turned into electricity. Or if you like Wikipedia’s definition:

“A solar cell’s energy conversion efficiency, is the percentage of power converted (from absorbed light to electrical energy) and collected, when a solar cell is connected to an electrical circuit.”

So I figure I need to see a chart of the efficiency over the last twenties years to see what the trend is like. If I find that the efficiency is doubling every two years I know that solar panel I purchase today will not be worth much in a few years.

I found a chart on Wikipeadia below.

efficiency solar chart

From what I can tell the most common solar panels are the Cyrstalline Si Cells. I can see that the trend is not to double every two years, at least not lately. So this confirms if I purchase solar panels now, I can feel pretty good that they will not become obsolete like my computer in 2 years.

Update: Looks like solar panels can be like computers, 40% efficiency might have been reached.