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.
An inverter is a device that converts DC or Direct Current power (the type of electricity stored in batteries) into AC or Alternating Current power (the type of power we use at home).n inverter is a device that converts DC or Direct Current power (the type of electricity stored in batteries) into AC or Alternating Current power (the type of power we use at home).