There was a major blackout on Friday before the scheduled protest.
President Nicolás Maduro and the US-backed opposition trying to oust him blamed each other for the failure.
Hospitals struggled to cope, and at least one hospital patient died when their respirator stopped working Power outages that began on Thursday were caused by problems in a large hydropower plant.
Venezuela depends on its huge hydropower infrastructure and not on its oil reserves for its domestic electricity supply. But decades of underinvestment have damaged the large dams and sporadic power outages are commonplace.
Electricity has been restored in some parts of Caracas and the rest of the country, and Venezuelans are now preparing for a weekend of protests against the government and against the government.
What's going on?
On Friday and Friday Vice President Delcy Rodriguez said the school had been shut down to support the restoration of electricity.
Some hospitals saw chaotic scenes as relatives tried to transfer patients in the dark to other medical facilities with emergency generators.
The 25-year-old patient Marielsi Aray died at the University Hospital of Caracas after her breathing apparatus stopped working.
"The doctors tried to help her by manual pumping, they did everything they could but without electricity to do them?" Said her uncle Jose Lugo.
Generators in a Caracas pediatric hospital failed, and the staff reportedly worked overnight with their cell phones for light.
"The children were very scared," said Emilse Arellano, whose child's dialysis had to be canceled, AFP news agency said.
Does the blackout affect the protests?
Mr. Maduro has accused the opposition of sabotage, which he calls "a new attack by enemies of the Fatherland," while his deputy Rodriguez condemned a "Imperial Electro War."
Mr Guaidó struck back and urged the Venezuelans to "demonstrate Saturday against the usurping, corrupt and incompetent regime that has brought our country into the darkness".
He said the blackout was the result of years of underinvestment and told a gathering marking International Women's Day that it could not be normal for "50% of the country's hospitals to have no electrical system." [1
The BBC's Will Grant in Caracas, however, says the blackout has affected public transport and mobility in the capital, and could possibly have an impact on turnout.
Why are power outages occurring in Venezuela?
Power outages are nothing new in Venezuela. Critics say that they have deteriorated since the nationalization of the power grid in 2007. In 2016, the problem reached such critical levels that the government declared 60 days nationwide state of emergency.
In an attempt to combat the country's chronic blackout, the government has regularly enforced controlled power outages that would shut off electricity for up to six hours at a time.
Critics say that this is far from helpful, that perishable foods have become bad and crime has taken over. And when unplanned power outages – such as the recent one – have occurred, officials have accused a number of outside forces, including animals such as iguanas that go into hydroelectric power plants.
What is the background of the political crisis?
Mr. Maduro Assumed Venezuela has experienced an economic collapse in recent years, with severe food shortages and inflation reaching at least 800,000% last year.
The Maduro government becomes more and more isolated More countries blame it for the economic crisis, which has left more than three million people in Venezuela.
Mr. Guaidó, who heads the opposition-controlled National Assembly, declared himself interim president on January 23 and is on a quarrel since then is he associated with President Maduro.
Recognized as Interim President by over 50 countries, Mr. Maduro continues to support his close allies Russia, Cuba and China.