The Enphase battery storage system consists of two components, an energy meter (Envoy-S) that monitors energy consumption and production and a lithium ion battery pack or packs with an integrated battery management system and inverter.
The Envoy S Energy meter is a mini computer that measures the energy production from a solar array and the energy consumption of the building. Energy production and consumption is measured via current transformer clamps which are connected to the AC output circuit of the solar array inverter and the AC inbound circuit of the mains supply to the building. The current transformer clamps are wired back to the Envoy-S which monitors the flow of energy into and out of the building. If the building is exporting energy to the grid the Envoy S signals the Enphase batteries to start charging in order to use up the surplus energy. If the building is importing energy from the grid the Envoy-S signals the Enphase batteries to start discharging in order to reduce the amount of energy imported from the grid.
The Envoy S is three phase compatible. A current transformer clamp can be connected to each phase of the AC output circuit of a three phase solar array inverter and to each phase of a three phase AC inbound mains circuit. Up to six current transformer clamps can be connected to the Envoy S.
The Envoy S communicates with the Enphase batteries using Powerline IP communication. The Envoys S itself is powered from one of the existing AC circuits in the building and will detect any Enphase batteries installed on AC circuits in the building.
The Envoy S can be configured not to discharge the Enphase battery packs until after a certain time such as five pm in the evening.
Data Sheet Installation Guide
Each Enphase battery pack is a self contained module consisting of battery cells, battery management system and integrated AC/DC inverter. Mutiple Enphase battery packs can be daisy chained together and installed at various locations around the building. The battery packs are connected to an existing AC circuit. The battery packs will draw power from the AC circuit and start recharging when signaled by the Envoy S that the building is producing surplus energy and exporting to the grid. The batteries will discharge power into the AC circuit when signaled by the Envoy S that the building is importing energy from the grid. The building draws from the external grid when the batteries reach their reserve.
Each Envoy battery pack has a usable capacity of 1.14 kWh and a discharge rate of 260 watts continuous. A cluster of 5 battery packs will provide 5.7 kWh of battery capacity and 1.3 kW of power. Up to 13 Enphase battery packs can be installed in a cluster giving a total output of 14.8 kWh and 3.38 kW of power.
Enphase battery packs have a 10 year warranty.
Data Sheet Installation Instructions
The Enphase battery system is particularly appropriate for electric car owners who wish to charge their vehicles in the evening from solar power generated during the day. An electric car uses an average of 1 kWh of power per 5 km of travel at freeway speeds. An electric car owner who travels 50 km per day uses around 10 kWh of power. In Perth a 5 kW solar array generates around 21 kWh per day. A cluster of 9 Enphase batteries will deliver 10 kWh of power at 2.34 kW continuous. An electric car pulling at 3 kW will get most of its power from the battery pack. The rest will come from the grid.
An electric car owner who wishes to re-charge an electric car entirely from the battery needs a pack that is sized to re-charge the car and provide power to the house overnight. Otherwise an electric car which starts charging in the evening will quickly deplete the battery pack and the building will cut back to the grid.