This is a uninterupted power supply. This unit has a storage of 8 batterys, 2 transformers and a hole lotta watts. This unit you charge up by ether a 120 outlet or hook it to your solar, wind, or any other power source you can think of. Then it will run what ever you have for a long time. In a criss situation it would run your fridge for probably 6 months or your house for 2 weeks. Very good to have. Very very very heavy.