The state's power generators have had a number of unit failures this month, but are confident they can operate through the hot weather without a hitch.

Victoria is forecast to hit highs of 38 and 37 degrees Celsius on Thursday and Friday, while South Australia can expect to see every day this week hit 30 degrees or above, spiking to 38 degrees Celsius on Thursday, pushing state power systems to their limits.

The states' energy systems have come under fire over the last two months as a number of coal-fired power station generator unit trips have raised concerns of critical failure ahead of this heatwave. A trip or a short is when the generator experiences an outage due to an overload or failure of the system.

Over the last four weeks, AGL's Loy Yang A power station has had at least six failures, while one of its units remains down.

Two units at Energy Australia's Yallourn power station have also recently tripped, and suffered a false start on Monday morning.

An industry insider said Victoria's coal-fired power stations were likely to operate well, but the real test would come if the wind was not blowing in South Australia.

"It will be an interesting test into this week, and it will depend on what happens in South Australia, as there is low wind forecast," he said.

This means South Australia could potentially be an importer, rather than exporter, of excess energy, and as New South Wales will be nearing its capacity, very little energy will be sent to Victoria, which almost matches energy generation with demand and leaves very little headroom for increases or stress to the system.

This means Victoria has a thin line between a well-functioning grid and failure.

"The system is like an old car that has lost its spare tyre, if everything is running well then the system is ok, but if any big generators go down then there are going to be big issues," he said.

Dylan McConnell, a researcher at Melbourne University's Climate & Energy College said despite the heatwave, Victoria's energy system is likely to hold up.

"However, it looks like there will be a challenge if Yallourn remains out of action," Mr McConnell said.

"Victoria will rely heavily on excess energy from New South and Tasmania towards the end of this week."

While the Australian Energy Market Operator has the potential to call on the Reliability and Emergency Reserve Trader (RERT) mechanism to draw down power from major energy users, Mr McConnell believes AEMO is unlikely to utilise it.

However, AEMO has issued a Level One Lack of Reserve notice for Victoria on Thursday.

This means a likely reduction in pre-determined electricity reserve levels and is released as an indicator to the market to increase generation. At this stage, it does not indicate there will be an impact on energy reliability or security.

There are three major coal-fired power stations still operating in Victoria, following the closure of the Hazelwood power station in March, last year.

The owners of both Loy Yang A - AGL - and Loy Yang B - Alinta Energy - are confident their power stations have the capacity for the heatwave.

"There are no issues expected ahead with the forecast hot weather," Alinta chief executive Jeff Dimery said.

"Loy Yang B has contingency plans in place in the event of any unit trips and fails."

An Alinta spokeswoman added, "Every effort has been made by the operations and maintenance team to ensure that performance is reliable during the peak loads associated with hot weather."

AGL is also confident over the operation of Loy Yang A, a spokesman said planned maintenance had been carried out on the plant last weekend.

The operator of Yallourn, Energy Australia, believes it has prepared for hot weather and higher demand.

"All of our units are ready to go by the time the hot weather comes on Wednesday and Thursday," an Energy Australia spokesman said.

The spokesman added that there are no planned outages or maintenance which will impact generation.