What you should look out for when installing a back up system.
Make sure that you can one day if you wish to upgrdae the system that it can be done.
How to know what size or type of system should my house require.
Its alwasy best to consider a systedm that has a battery and a few solar panels, because just having a inverter and batteries, its still putting straing on th enetwork and costing you now money to fill again, but by having panels to bsicaly chrage the batteries and keep the house on is always the best option.
If its to cheap then you know that there is something someone is not telling you.
Make sure as to what you are installing is a credited and has all the documents in place to register and make sure the warranty and guarantee is in place, make sure surge protectors and fuse housings and fuses are installed between the Inverter and the Grid and the Inverter and the batteries thsi is a must.