I will like to use 26 micro-inverters with 26 300W-PVs in an array to deliver AC to a string inverters AC input. The string inverter will have a battery bank attached to it so that the AC source will treat the batteries as a backup for charging whilst there is daylight and with excess power delivered to the house. In the evening when the sun is no more the string inverter will sense low AC and then switch to invert power from the battery to serve the house. Can this work beyond theoretical view? What inverters will be best recommended for this arrangement?
Comments
The system described above would be categorized as an offgrid AC-coupled PV system. In these systems there are two types of inverters utilized: grid-tied and battery based. From your description, the micro inverters woud be the grid-tied inverter and the 'string inverter' would be the battery-based inverter. The battery-based inverters act as the AC source in this architecture providing the microinverters an AC waveform to sync with. When the sun is shining, the energy harvested by the PV array and delivered by the micro inverters is sent to the site's AC loads. Excess energy is delivered to the batteries. If the PV system doesn't have enough energy to power the AC loads the battery-based inverter will supplement with stored battery power. When the sun isn't shining, the battery-based inverter provides energy to all of the loads. Many times a generator is used in parallel to ensure power is available at all times. When a generator is present, a system must be in place to disconnect the grid-tied inverter form the electrical system.
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