Monroe’s explanation only applies to optical systems, ie reflecting and focusing light, which is a thermodynamically reversible process (yes, even with dust. Du

Monroe’s explanation only applies to optical systems, ie reflecting and focusing light, which is a thermodynamically reversible process (yes, even with dust. Dust doesn’t make the lens thermodynamically irreversible, it just scatters and absorbs some of the light so it doesn’t reach the lens. The irreversibility is a property of the lens). Solar panels are converting light energy into electrical energy, which is not an irreversible process - it creates entropy, and therefore the rules are different.