I wonder if these would do well in the wild? If so there is a huge ethical issue here.

I think a more likely possibility is that they might be like like most domesticated photosynthesizers. Loose populations would revert to more natural traits and become less useful to humans and barely struggling for survival.

Consider what happens when farm grown tomatoes or corn go wild. The vast majority die off because their fruit wastes a ton of energy becoming huge and visually appealing. Those with just enough fruit to entice animals to spread it, those that grow faster and those with the best resistances will succeed in the wild.

Can these bacteria benefit from these solar cells without the help of humans feeding them? If they could then natural selection will reinforce our decisions and we could have a real threat.

I agree the risk reward part of this needs careful analysis, I don't think we need to go straight to doom and gloom.

EDIT - Speeling, and grammar.

[1] gives example how simple selection for better use in agriculture gives big problems a few years later when the plant mutates in wild into a nasty pest. Situation is especially sad in poor regions of Russia North where lack of money in local budgets allowed the plant to spread everywhere. Driving there is like watching illustration for "The Day of the Triffids" by John Wyndham [2].

[1] - https://en.m.wikipedia.org/wiki/Heracleum_sosnowskyi

[2] - https://en.m.wikipedia.org/wiki/The_Day_of_the_Triffids

Just don't let them near the oceans - although that does sound like an 'ice-9' situation from a terrorism or MAD point of view.