# Small Off and On Grid ICE system



## john10001 (Mar 20, 2013)

A battery a small solar panel, a charge controller, a small grid tie micro inverter.

The solar panel tops up the battery during the day and feeds excess back to the grid through the plug-in grid tie inverter.

Until such a time as there really is a SHTF situation and I'm totally off grid I'd also like to use the battery power to put back small amount during night time. 

How would you hook this up and control the flow so that you don't deplete your battery by more than half?

Would the charge controller handle all this? Would it be able to take from battery power, to load, to grid tie inverter, at night time when nothing is coming from the panels? How could I control the drain from the battery so that it doesn't lose more than 50% of its capacity then it waits until the next morning to start topping up off the panels again?

In the middle of summer I might only need it to put back to the grid at night time for a few hours, but in Winter over several. Can you vary the rate or will it not make any difference?

Apologies if these are dumb questions, I have zero experience with this sort of system other than what I have read so far.


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## paraquack (Mar 1, 2013)

An easy way to control the usage of the battery is to do the math, figure out what 50% of battery capacity is. The figure out how many lights, TV, etc. would consume that 50% over the number of hours you want to use it. Example: battery is 2700 watts, 50% = 1350 watts, TV set consumes 100 watts/hr for 3 hours =300, lighting consumes 120 watts/hr for 3 hours = 360, this is 660 watts so far, fridge consumes 600 watts/hr while running (but lets say it runs only 15 minutes/hour so it's really 150 watts) so it really consumes 450 watts for 3 hours so you still have 300 watts to spare before you hit the 50% limit for extras or if you open the fridge a lot to get the beer out. If you go to LED bulbs you can save a lot of power in the battery for more hours of use. I've converted a big chunk of my house to LED and saw a big change on my electric bill. Waiting for more styles (bases and shape) to come out so I can change them all.
Hope this helps.


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## john10001 (Mar 20, 2013)

So when I am putting back into the system via grid-tie micro inverter you're saying it will drain at the rate of all the appliances currently switched on? 

There is no way to prevent such a fast drain so that it for example only puts back 5 amps an hour regardless of appliance drain, the rest which would come from the grid anyway?

My appliance drain is likely to be more than what I put back so in essence I would only be preventing the meter from going forward as quickly. In the daytime when solar connected, just preventing it from going forward.

Would a grid tie inverter draw power until the battery is flat? I don't understand completely how it would work and if there is a way of controlling it?


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## paraquack (Mar 1, 2013)

Nope, sorry to have mislead you. I thought you were talking about how to use for yourself, only 1/2 the battery capacity. What I described has nothing to do with limiting flow out of battery into the grid. Once your batteries are charged, you could send everything from the panels into the grid. Just have a nice big disconnect switch at the batteries. Battery Switches by Discount Marine Supplies Or you could use big diodes to prevent batteries from draining.


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## budgetprepp-n (Apr 7, 2013)

How many watts of solar panel are you talking about?


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## Prepadoodle (May 28, 2013)

You might want to consider setting up a straight grid tie system without batteries. In effect, you would be using the grid as your battery bank.

You could have some batteries on hand, stored dry, and not hooked into the system. If the grid goes down, it would be easy to add the electrolyte and wire them into the system.

Such a system would be less expensive, simpler, and still let you produce your own power if needed.


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## john10001 (Mar 20, 2013)

Am I correct in understanding that a Solar Charge Controller will top up and battery connected to it and once that battery is fully charged it will switch automatically to "load" and start powering whatever is connected on the load? E.g. a light bulb, or grid tie inverter connected to the mains?

If so, am I also correct that a Solar Charge Controller once it is no longer getting enough power from the Solar Panels after sunset it will then switch to take power from the topped up battery if anything is connected on the load and using power? E.g. that light bulb, or, grid tie inverter?


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## budgetprepp-n (Apr 7, 2013)

In Readneckaknees, Sorry I can't speak teckanees,
Mine goes like this,, On a sunny day it stops charring at about 13.5 - 13.7 
And if I flip on a light it doesn't change so yea,, I would say it's running right off the panels. 

And after sunset I'm sure The same lights must be running off the batteries it has nowhere else 
to get any electric. My system is not tied to the grid. 

And to the other 1/2 of your question about tie converters,, I don't know anything about it.
I'm watching myself to see what the correct answer is to your questions 

If an EMP were to hit everything tied to the grid may become toast
I try and stay away from that monster it may bite you hard.


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