Some questions on pv basics

[jvnn]

- Can I run an off-grid system with no battery - just collectors and an inverter?
-What happens to your collectors when your inverter is not drawing?
-Is it possible to run collectors to a grid-tie and then manually switch to a standalone off-grid inverter when the grid goes down?

I'll think of some more eventually...
Thanks guys  -Joel

[DamonHD]

Off-grid generally needs battery for a variety of reasons of which

(a) how do you run loads when the sun goes down or behind a cloud and

(b) voltage regulation

are amongst the main ones.

Rgds

Damon

[jvnn]

Ok, thanks.

When the batteries in an off-grid system are depleted (eg too many cloudy days) do the inverters shut down cleanly?
ie protect the batteries, not cycle on and off due to hysteresis?
Another way of asking, is it possible to run a solar system that is grid-tied, but switchable to off-grid and using a smallish battery bank?

-Joel

[DamonHD]

Yes, most inverters should shut down when the batteries are low, but usually too low to be good for the batteries.

Yes, "grid interactive" systems exist, though sometimes with slightly different targets such as to act as a whole-house UPS for short grid outages.

Look at SMA, Outback, Xantrex for example, IIRC.

Rgds

Damon