[pmrid (Peter)]

I'm gradually weaning myself off the grid. But because I don't have an electrical or electronics background, I have to be quite frank about what I don't know. I suspect I'm not alone either in wanting to be more off-grid and lacking that sort of background. So I thought I might propose a sticky thread to deal with all things renewable as it applies to our hobby (obsession).

To kick it off: I've had a grid-connected system for 6 or 7 years now and still have the benefit of the early and bigger rebates that were offered. So my domestic power bills are currently fairly negligible. That will change with time since the unit prices are always going up and new connectivity fees and charges are being added and are also on the way up. And the rebates are not indexed. In time I may have to go fully off-grid.

But for the moment, the next area I have targeted for a full conversion to renewables is my observatory. But I'm struggling to get my head around the various equations that determine the sizing of the system I need.

I have recently made an impulse buy of a small wind-solar system (1 x 400 watt turbine and 200 watts of panels with a controller but no inverter). I also already have 3 x 105 AH deep cycles 12 VDC batteries I can connect.

My existing 500 watt Sine-wave inverter will be way too small so I am reconciled to having to replace that among other things.

In my obs I have several scopes on their own piers. It is not unusual for me to have at least 2 of them working at any given time (night-time only of course) and there are various internal lights etc in the warm room, a separate little IBM linux-based micro system running some music. All computers and mounts/scopes/cameras are currently sitting behind their own UPS. In a wholly offline system those UPSs may no longer be necessary (I suppose).

An important reality to keep in mind these days is that there is often (usually) a fair time between imaging opportunities. That is fairly seasonal of course. Over recent years, I've not had much imaging between about November and April. And even in winter, I usually only image a week either side of the new moon. So there are often long periods during which the system is not consuming much if any electricity. When I am using it, however, it will often run 4-6 hours at a time. And in winter, add some extra demand for running dewstraps etc.

Has anyone already been down this road? I'd sure be grateful for some guidance.

Peter
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