Should You Use Your Batteries to go Off Grid?
If you are thinking of getting solar and batteries for your home, then you are probably excited by the prospect of cutting the cord to the grid, and never paying a power bill again.
But is that a realistic proposition?
In theory, you can go 100% off the grid with enough batteries, a special off grid inverter and a generator to provide emergency power in extended periods of low sun.
However there are 3 big problems with taking this off-grid route:
1) Your system will be 2 to 3 times more expensive because you need to buy:
a. A shed load of batteries
b. A second inverter called a 'battery inverter' to ensure the batteries charge and discharge correctly and to balance the loads and generation (because there is no grid to mop up your excess solar).
c. A secure shed to store those batteries.
d. Lots of time from an off-grid expert to design the system so you won't run out of electricity too often.
2) Every so often you will run out of electricity.
3) An off grid system is not a case of install-and-forget. They need a lot of maintenance. Expect to perform 10x the maintenance compared to a plain-vanilla grid connect system!
So having said that, why would any one be crazy enough to plump for an off grid system?
Here are 4 reasons you might choose to go off grid:
1) There is no electricity grid where you live. Perhaps you live in the middle of the Simpson Desert like my Uncle Dave (seriously, he does!) or somewhere else equally remote. Hey, there's no shortage of places like that in this big ol' country of ours!
2) The nearest grid connection is a long way from your home and your local
gougers electricity network wants to charge you an arm and a leg to connect you. In this case it may actually be cheaper to go off grid - but be aware that a decent sized off grid system is going to start at approx. $25,000.
3) You are connected to the grid but you suffer frequent blackouts that really cause you grief. You want a system that can run when the grid is down and you understand that a standard grid connect solar system cannot operate when there is a power cut - unless it is a hybrid solar system with battery backup capability.
4) You're crazy. Your house is already connected to the grid. Blackouts aren't a problem, but you just like the sound of going off grid. You think it makes you more "independent" and protects you from the forthcoming apocalypse.
In fact, you've already got a big shed to put the batteries in. It's the same one where you stored all the canned food in readiness for the Y2K bug / end of the world last time round - and you don't mind spending $25k on an off grid system that would only cost $8k if it was grid connected. Or maintaining it 10 times more frequently than a grid-connect system. Or buying new batteries every few years. Because you are much closer to nature now you have cut that grid connection. . . Yeah - right on man! Peace!
I guess what I am trying to say is that unless 1) or 2) or 3) above applies, then it is kind of economically and environmentally insane to insist on an off grid solution.
Economically insane due to the cost being 3x higher.
Environmentally insane due to all those batteries you need to buy (and replace periodically) which contain a lot of really nasty chemicals.
For that reason, the rest of this guide is going to assume that you are thinking of buying a grid connect (hybrid) system for your home.