Post #9548

A couple of weeks ago, I set up a sand battery to provide stable heat and humidity to an indoor greenhouse. It is a 60v commercial heating element directly connected to two 310 watt solar panels (series). The container is an obnoxious red thing I found at the thrift store. The sand mixture is 50# of playground sand and 5# of aluminum shavings from eBay. There's a bowl of water on top of the sand that adds humidity when the sand is warm. Ever since I installed it, the greenhouse has maintained 75 to 80 degrees f and 50 to 65% humidity. I installed a cheap shunt into the system this weekend and measured about 2kwh of energy into the sand, stored as heat.