I'm sure there is, but what is the cost and how much heat would it produce? Can you just hook something up to your EKO 25? There is one place that I did some electrical work for about 7 years ago that had solar collectors for heating water. They ran the system all year long. They had a large warehouse that they had put about 8' of sand below the concrete slab. They used this sand as their heat sink during the summer to draw off from during the winter. The solar did produce heat during the winter, but I think it was more supplementing the heat that was stored in the sand. I never heard how well this system worked for them.