How justified it is to use a 0.5 KV inverter to light up 10 W CFL? Can any body suggest a beter option? Please?

I have 0.5 KV inveter and as the electrical supply is available for very short duration hardly for 5 Hours in a day in random manner. I have to preserve the power for Night lightening, using Few 10Watt CFLs. I think that the running of the inverter may itself be consuming more than 10Watts (I do not know exactly , will some body let me know ?). Will it be better option to use separate 10Watt kits to light the CFLs from the battery instead of through the inverter. Pleas Guide.