The Self-Powered Harvester Kit is a No Trade deed that can be obtained from the
PAAS. Possessing this deed enables a 'convert harvester' option on a deployed harvester, which will remove the power(but not credit) maintenance need of that specific harvester. Re-deeding or destroying the harvester will refund this deed.
Three of these can be combined into an Self-Powered Elite Harvester Kit to be used on an Elite Harvester.
An alternate, and generally more successful, method of apply the deed is to: put it on your toolbar, mouse-over the harvester, and use the kit via the hotkey.