How much efficiency do they lose? What else reduces efficiency, and is the trade off to moving them to a different location worse? On the first one: let's look

How much efficiency do they lose? What else reduces efficiency, and is the trade off to moving them to a different location worse? On the first one: let's look at a high end model like https://www.energysage.com/solar-panels/sunpower-corporation/774/spr-e19-320/ https://www.energysage.com/solar-panels/sunpower-corporation.... You will see the temperature coefficient of PMax and Voc in the specs. The PMax in this case is -.38. You can predict a panel's loss of efficiency by multiplying the difference in degrees Celsius from standard testing conditions. Standard testing conditions for a solar panel is at 25 Celsius. A hot panel in summer will get up to 65 C. So 40 x -.38 in this case, or just a bit over a 15% loss. That is not great, but 85% of max efficiency is not ridiculous. Panel orientation, angle, and shading can easily add up to more than that. The second question is a much harder one. What's ridiculous is not having solar panels.