Energy Minister Fortune Chasi today said Unit 5 broke down yesterday but Unit 4 is likely to come back online this afternoon reducing the deficit to 670MW.
He could not say when Unit 5 will be back in service.
Zimbabwe has been experiencing power shortages because of low dam levels at Kariba and lack of foreign currency to import enough power.
Harare has, however, resumed power imports from South Africa’s Eskom and is negotiating more imports with Mozambique and Zambia.
The power shortages are also being worsened by thefts and vandalizing of transformers which have prompted the government to ask for stiffer sentences of those who vandalise or steal transformers
Chasi said some 927 transformers were stolen or vandalised in Mashonaland provinces, 625 in Matebeleland and 575 in Harare.