Sizing Off-Grid Systems And Using Gen Support

Thanks for a very interesting thread....it was enough to get me to register.

I live on an island off southern Tasmania with a system that I would recommend to anybody.

I run a system by a company called SMA.

The main product in the room is called a Sunny Island inverter/charge controller.

Some of it's features are full generator control, user programmable to load share and charge as per the original thread topic.

It does this absolutely comprehensively.

But...the best feature is that it can interact with standard grid tie inverters fooling them into thinking they are connected to a utility grid.

This makes it scaleable to almost any depth, utilising cheap grid tie MPPT inverters which the Sunny Island then uses to keep the batteries maintained.

Battery charge controllers and the array connectivity here is 15kw to 48 volts...done cheaply...

It does this by phase shifting (or mis-matching) to keep the input load under control.

Absolutely bullet proof and state of the art.....worth a look for anyone contemplating a new setup.


My setup:-

Sunny Island 8.0H controller
Sunny Island SB5000TL 5kw grid tie inverters in off grid mode X3
BP monocrystalline 190W panels x 72
200AH 12v AGM lead acid batteries organized as 8 banks of 4 in series/parallel 48V strings...1600AH in total @ 48v
Auto start 5kw diesel generator.

I run a seawater desalination unit and stock standard resistive element hot water system, clothes dryer, microwave ovens etc.

Desal uses 3kw and produces 300L an hour....or 10w/Litre to make drinking water from seawater with reverse osmosis.

The Sunny island can be user programmed to charge batteries, when batteries full hea tthe hot water, when water hot desalinate seawater....etc etc

Our aim was to make living as close to being on grid as possible.

We consume around 25kw a day, with washing etc done when the sun is shining to keep battery DOD to around 10-20% maximum.

I cannot remember the last time the generator kicked in.

Panels are so cheap now we sized our arrays for worst case conditions...winter/overcast....so most days by 10am batteries are charged to 100%.


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Long, thorough discussion about generators and loads. Even a section on LED light quality (color & intensity) Done by a movie company rental site.
in the old days, generators ran lighting which was all resistive loads. Now CFL and LED's use weird ballasts that muck up the power factor and that messes up the generators
http://www.screenlightandgrip.com/ht...enerators.html

some great charts and links to videos in there.

Ok this is all so new to me it is making my head spin, I am trying to run my TV, internet modem and cable box. I have one 100 watt renogy panel and a 175 ah 12v battery with a 1500 watt inverter, I live in the san luis valley of Colorado and get some of the best solar sun in the US at 7800 ft. I have 3 more batteries and 2 more panels. I am trying to use the other two panels and the other two batteries for some greenhouse applications. Is my setup for my TV and internet adequate? I really only need to use the internet and tv at night for about 4 hours max. Sorry for the newbie question but this is sooooooooo far above my level of knowledge it is scary

ChrisOlson, you mentioned that you use a very small air cooled Diesel Gen for you small prime gen, can you give us some detail on your generator and possibly some of the selection criteria you used?

You are talking to ghost. Chris has not been here for 2 years. So do not hold your breath. Well you can hold your breath. If you die, then you can talk to Chris.