Eskom had planned to sign the agreements on Tuesday.
In the ruling, the court says: "The respondents will have circumvented the process which is now pending before court; and the applicants will have no choice but to institute applications to review and set aside the awarding of the contracts".
The North Gauteng High Court, based in Pretoria, will hold a full hearing into the matter on March 27, the union said.
After arguments were concluded, the court refused to grant an interim interdict against Eskom or the Minister but instead postponed the matter to 27 March 2018, with the responding parties to file their answering papers by 20 March 2018 and the applicants' parties to file their replying papers by 22 March 2018.
The NUMSA injunction forced Radebe to agree that the renewable PPAs would not be signed until the issues raised had been subject to a full hearing by the court, according to a statement from the union.
This is a victory for NUMSA.
The protesting trade union believes that the inking of the contracts "would be detrimental for the working class of Mpumalanga and the country as a whole".
Numsa, which represents thousands of workers in the industry, fears the signing of the agreements would lead to Eskom needing less coal-powered electricity and ultimately result in the closure of power plants and job losses. The ANC government clearly wants to make the working class and the poor suffer even more than they do now.
"Electricity prices will skyrocket because of the IPP roll-out; while at the same time that Value-Added Tax and the fuel price are going up, workers are being paid slave wages of R20/hour and less".
Nonetheless, this is despite a recent report by the CSIR stating renewables are way cheaper than fossil fuels. The 27 projects include wind, solar photovoltaic (PV) and concentrated solar power (CSP) technologies. Moreover, the union says that renewable energy would boost electricity prices.
Numsa and Transform RSA launched a late night high court bid yesterday to urgently interdict Eskom from signing the 27 (IPP) contracts on Tuesday. The utility favored a nuclear-build program at the time and maintained a standoff on what was once a successful program by the Department of Energy to diversify South Africa's power mix and bring in billions in foreign investment.
"This initiative will enable R56 billion of new investment in the economy over the next 2 to 3 years‚ which will immediately contribute to growth in the economy".
Eskom argued previously that renewable energy is more expensive than the energy it generates from its own coal-fired power stations and tried to impose a cap on the tariffs previously negotiated between the department of energy and the independents.
"The government of South Africa reconfirms its commitment to a solid public-private partnership as we pursue our energy transition objectives of the future as well as a better life for all", he said.
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The order leaves out Canada and Mexico but applies to every other nation, according to the White House . Liddell was born in Matamata and was chairman of Xero before he joined the Trump administration.