Nine plants suffered a breakdown and others face gas shortages.
Nigeria suffered an extensive power outage in recent weeks because 18 plants accounting for most of the electricity the country generates had faced operational problems, the government has said.
The Minister of Power, Saleh Mamman, revealed the cause of the blackouts only on Thursday, weeks after many Nigerians had complained of persistent outages.
Mr Mamman said eight plants suffered a "breakdown" while one underwent an annual maintenance.
Seven other integrated power plants were experiencing gas constraints while one hydroelectric power plant has water management issue, he said.
"I sincerely regret the recent Power outages across the Nation and the difficulties it has brought with it. The problem is caused by the breakdown of some National Integrated Power Plants supplying electricity to the national grid," Mr Mamman tweeted Thursday.
"The plants are namely, Sapele, Afam, Olonrunsogo, Omotosho, Ibom, Egbin, Alaoji and Ihovbor. The Jebba Power Plant was shut down for annual maintenance.
"Seven other integrated Power plants, namely Geregu, Sepele, Omotosho, Gbarain, Omuku, Paras and Alaoji are experiencing gas constraints while the Shiroro hydroelectric power plant has water management issue," he said.
The breakdown is significant for a country that has perennially underperformed in power generation, transmission and distribution.
For years, Nigeria has only generated an average of 4,000 megawatts for a population of 200 million.
Malfunctions are common in the sector and often result in extensive blackouts across the country. The government cites gas supply issues despite Nigeria being one the world's largest producers of gas.
Mr Mamman said there are efforts to resolve the power outage in the country as "everyone involved is working assiduously to restore the National grid to its previous historical levels and exceed that."
A statement by the spokesperson Ministry of power, buttressed the position.
"This unfortunate development has drastically affected power generation, thus effectively minimizing the national grid," it said.
"In view of this, the Minister of Power, Engr. Sale Mamman regrets this unfortunate situation and offers his sincere apology to all affected Nigerians on the inconveniences the power shortages are causing."
The minister hopes the national grid will be restored to its previous distribution peak of about 5,600 megawatts of electricity achieved early this year, to help Nigerians battle the prevailing climatic condition while restoring full economic activities.
Earlier Mr Mamman said Nigeria's installed grid power generation capacity had grown from 8,000 MW to 13,000 MW between 2015 and 2020 while the distribution system had the capacity to evacuate 5,500 MW of power having grown from 4,500 MW in 2015.