Old Vs New Solar Panels - Tested! 

And I was thinking about discarding old name brand panel from my storage. Old 90w siemens panel, I think it’s deserving a second look. Hardly used as is.

Looks like the chinesium stuff is running approximately 70% "rated", while the Siemens stuff is knocking on the door of 90%. No doubt the chinesium stuff is likely cheaper, but for 20+ years on those Siemens panels that's really impressive. I've no idea if the photovoltaics of the cheaper stuff would live as long or not but I'm certain the fabrics they're mounted in would not.

Has anyone ever told you, you sound exactly like tony stark.

All things being equal, they all lose some of their output potential as they age, but newer panels can start with/give better power density and then as it ages it should remain higher than the older less power dense panels, but it’s unlikely to be worth the cost to replace older panels unless the panels you have are outputting meaningfully less than what you require. The type/manufacturing method also plays a large part in their performance profile. monocrystalline, polycrystalline and thin film all behave differently and have different costs.

We need better panel recycling. They are environmentally nasty.

First!