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.

drawing a circuit diagram for the original and the new circuits would be a first step in figuring out what could be wrong. Other things - measuring the current draw for the original vs the new, checking for breaks in the solder, polarity.

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

Thanks so much for the encouragement everyone. I was planning only 10 roses in the backyard before I found this forum. Lol. Now I have I think around 70 in the back yard. But on my own, I had already planted about 60 azaleas in the front yard and maybe 30-40 roses throughout the past 3 years (although a lot are just carpet roses for drought tolerance)... and that was before I found this forum, so obviously I had the pre-existing propensity for this. ;) I didn't really need a lot of arm twisting or convincing to go for more! Everyone here has helped me so much. Please if you're in the Bay Area of northern CA, direct message me and maybe I can invite you over! :)