Q:
Sean,
Per the Week 4 video for off-grid setup PV - DC disconnect - Charge Controller -Batteries - Off-grid inverter
Is using micro-inverter with off-grid possible? With off grid systems there is nowhere for excess energy to go. Is this where diversion loads are utilized.
thanks
A:
I have heard rumors of an off-grid microinverter, but have never seen one, they are as common as unicorns. It would be difficult to connect to a battery.
That being said, Enphase (the biggest microinverter company) has plans for what they are calling an ac battery. It will be a battery inverter that is connected to the ac side of a microinverter system.
https://enphase.com/en-us/products-and-services/storage/our-system
There are also other ways to connect any grid-tied/interactive inverters, including microinverters to ac coupled networks.
An ac coupled system will use a battery inverter to make a micro-grid that you can connect microinverters to. This is expensive.
Here is an example of an ac coupled system with microinverters:
http://www2.enphase.com/global/files/Enphase_Application-Note_AC-Coupled-Battery-Based-Systems.pdf
With off-grid systems, diversion loads are a good way to make use of the array's potential when the grid is down, however you still have to have the ability to turn the PV off if the diversion load breaks by Code according to 690.72(B)(1)
Thanks!
Sean White