My son got me some for a gift that are on the shepard's hook (which are metal, not plastic). I have had them in the ground for about 7 years. Where we use to live, we had very cold freezing winters and I never brought them in. Now we live in very rainy weather in the spring and warm in the summer, still leave them out year round. Have not changed the batteries yet either. They look old fashion, too. The newer ones he has bought me, with just the stakes with lantern on top (plastic), two have broken already. Hope this helps.

I try to reflect any "excess" light back onto the plants.

Hi chemocurl, thank you for the link. Why didn't I think of that? I checked some of those out and did find some commercial solar flood lights that would be great around the home and garden, although they are quite a bit more expensive, $300 compared to $80 for the domestic models. They are rated at being as bright as 100w to 150w, which is fantastic and way more than the domestic variety. I guess you get what you pay for!

It is not a matter of efficiency. Solar panels generate energy only when there is sufficient light. Batteries are needed to store the energy harvested by the solar panels for use at a later point in time (night). If the lights run on line voltage/ low voltage, you could conceivably use a GoalZero or similar system (Inergy, ...) of panels + battery. Or you could get something like powerpractical's luminoodle and combine it with your solar panel of choice. https://powerpractical.com