The ESRI says electricity generators that were ordered simply haven't shown up.
Muireann Lynch, senior research officer, was speaking after Eirgrid issued a system alert.
It says while there is enough electricity to meet demand, there's possibly not enough in reserve if something goes wrong.
It says the buffer between demand and supply is currently smaller than optimum.
Ms Lynch told Pat Kenny it's an extraordinary situation.
"The balance between demand and supply - we just don't quite have the buffer on the supply side that we'd like to see, and that's the reason for these alerts.
"We don't generally see an awful lot of wind generation in the middle of the summer.
"And now for what we call a winter peaking system, like Ireland, that's not necessarily a huge issue.
"When we have those really high wind levels, they tend to correspond with those really high demand levels in the middle of winter.
"But one of the things I'd be very keen to point out here is that this is not wind or solar's fault."
'Never relying on wind or solar'
She says the back-up systems are simply not there.
"We're meant to set up the system and the market so that we have enough electricity supply even when demand is very high, and there's no wind at all - and also not to rely on the interconnectors.
"The market doesn't seem to have delivered: there were generators that were contracted to be up and running by now, but they just didn't show up.
"So I think we certainly need to have a look at our capacity market to see why is it the case that we're seeing these alerts?
"Why didn't we get the generators we expected to have?
"But it was never the case that we were relying on wind or solar to keep the lights on.
"I want to make sure that's really clear".
And she says we need to look at our forward planning.
"We tend to try to contract years out - so we run an auction four years in advance saying 'Who wants to build a plan in four years' time?', and then three years' time and then two years' time.
"This was all supposed to be taken care of, and it clearly hasn't worked.
"I think we need to go back and take a look at our market design and say 'What is it about these contracts for capacity that haven't worked' - and why are we scrambling around trying to get emergency generation for this winter and next?"