This might be doing something for your greenhouse, but it doesn't appear to do anything for the batteries. They are not subjected to direct sunlight anyhow, and this contraption would have to be three times the size to help if they were.
Car Umbrella from Reliancer
Since there is no covered parking where I work. They won't let me plug in and I know it helps with keeping the batteries cooler when it is plugged in. I went out and bought a Car Umbrella. Last Friday It was 120 degrees inside my car. When I got to work Monday morning I installed it on my car. When I left work it was only 100 inside. I figure this thing will help with keeping the batteries cooler.
