well how much power are you sucking
if you're not running hid's then you could use a UPS (uninterruptible power supply) which can run typically for 5-20 minutes.
they typically come in 200 watt size but the largest i've seen was 6,000 watt capacity, however they were a couple grand
otherwise if you are pulling some heavy wattage it may be more cost effective to purchase a generator for small power outages.
however if this is a daily reoccurring problem i would call an electrician to come check out what is the cause of your daily outages