The best bang for the buck in a small system is Sound Wisdom’s SG-EU, which offers 5,000 watts of 220-volt Australian current, two 120-watt solar panels, 230-amphours of battery, and a 40-amp charger. Unlike all the other small backup systems out there, Sound Wisdom’s systems are indefinitely expandable: you can add as many solar panels and batteries as you like, as you get the money. You can even add panels and batteries from other companies; it’s open architecture. You can also take the output from a windmill, water wheel, bicycle generator, gas generator, whatever, and feed it straight into the battery bank to be stored for when you need it back as household current.

You won’t find a better system unless you need milspec, you won’t find a more cost-effective system anywhere, and there is no other system below milspec that is indefinitely expandable. And, your purchase helps support charity work; always a good thing.
References :
http://www.sound-wisdom.com