Adapt solar panels for off grid power in Queensland floods

An acquaintance in Brisbane, while not flooded has had power cut. They have solar panels on the roof, but these are mains interconnected and so not working. I was going to suggest they adapt one panel for an off-grid supply. Will this work and is it safe (they are reasonably proficient with cabling). These instructions are cryptic, as they have no Internet access and I have to send this by SMS:

To get some mains power from your solar cells. Assuming Dick Smith or similar is open. Three steps follow:

1. Buy a $20 multimeter from Dick Smith. Unplug a solar panel and check for 10.5 to 15 volts.

2. Buy a Dick Smith 300W Power Inverter $79.98, POWERWARE 700VA Uninterruptible Power Supply $149, 12VDC inline Fuse Holder, 35 Amp fuse and 12V cable to reach from roof.

3. Cable panel to fuse to indoors. Connect multimeter inline in Amps mode and connect to the inverter. Plug Inverter into UPS. Plug appliances into the UPS.

On sunlight will run up to 300 Watts (check meter: amps x 12 volts = Watts). UPS battery run your ADSL modem and a phone charger for few hours.