Storing water in a cistern or tank has many advantages. It's less expensive and more efficient than storing power in batteries. Since water is always a critical issue, we recommend the tank should be able to store a minimum 3 to 6 days worth of water or whatever you think your needs may be during cloudy weather or in case of a system failure. Generally speaking, animals, plants and humans use less water on cloudy days. Conversely, the sunniest days are when we consume the most water and when the solar modules are providing the pump with the most power.
At the very least a pressure tank should be installed however be aware that most 80 gallon pressure tanks will only provide approx 50 gallons of water back up. the Grundfos SQ flex pumps are the only submersible pumps that can be used in conjunction with a pressure switch. The pressure switch used on the Grundfos SQflex system is a reverse action type. In our house we pump water from our well into a 3000 gallon cistern and then have a Dankoff Surface Pump to pressurize the water in our house in conjunction with a 80 gallon pressure tank.
Do I need a water storage tank or cistern?
