[thelastgallon]

Old panels are continuously being replaced with new panels. This is happening now with a few year old panels. So many free old panels available, because new ones are producing 590W/panel. Over 25 years, there will be a lot more advances, panels that will be printed by textiles, or painted on surfaces, or grown by bacteria.

[SlightlyLeftPad]

Wait, where are these free old panels and how do I get some?

[KellyCriterion]

if you are in EU: https://www.secondsol.com/en/index.htm

[ambicapter]

How big is a panel?

[chipsa]

Very much depends on the rating. A residential panel is something like 65”x40”. A commercial sized panel is something like 80”x40”. The cell size is relatively constant, but the bigger panels are 6x12 cells instead of 6x10. Newer panels have more efficient cells, and so higher power.

Panel manufacturers can also do odder sizes as required. Example: q-cell does a 94x51” panel. This is 6x22 cells, but different sized cells as well.

Most panels are 6x, because that results in an open circuit voltage of just shy of 50V, which is convenient for code compliance.