Shelley was a key member of a close circle of visionary poets and writers that included Lord Byron; Leigh Hunt; Thomas Love Peacock; and his own second wife, Mary Shelley, the author of Frankenstein.
If the 900 watts means the input power, then 1000 w inverter would be ok. If the microwave produces 900 w of cooking power, you will need a bit more, maybe 1200-1400 w if you don't know what the input power rating of the microwave is.
You are here. How To Determine What Size of Inverter to Use. All inverters are rated in watts and most electrical appliances have a wattage rating. Use our online Calculator Tool to ensure the wattage rating of the largest load is within the wattage rating of the inverter you select. Pure sine wave inverters can run any of the modified sine wave inverter loads, as long as they meet the same operating and surge requirements of the load.