Concerns have been raised over a £3.3 million solar panel project at the under-pressure Grange Hospital.
The project, initiated by Aneurin Bevan University Health Board and funded by a grant, involves installing a solar panel canopy at the Cwmbran hospital.
However, there are worries that it may offer a poor financial return and exacerbate existing parking issues in the short term.
Figures, revealed under the Freedom of Information Act, indicate that the solar canopy will generate around 645,000 kWh of electricity annually.
The health board claims the scheme will pay for itself in 19.7 years.
But a local Senedd member thinks it could take longer.
Natasha Asghar, MS for South Wales East in the Senedd, said: "The Aneurin Bevan Health Board should be concentrating on sorting out A&E waiting times -- not investing millions of pounds into renewable energy schemes which may not provide a realistic financial return.
"I've done some quick research on electricity prices and seen that large commercial users are paying around 21.7 pence per kWh.
"On that basis, the project won't pay for itself for almost 24 years, by which time the solar panels will be nearing the end of their life.
"That feels like a really bad use of public money which could have been better spent on much-needed improvements to facilities at The Grange."
She also highlighted the impact on parking, stating that the project will cause "temporary, but serious, parking disruption".
Ms Asghar has written to the Senedd's Public Accounts and Public Administration Committee, urging them to assess whether this project offers value for money for Welsh taxpayers.
She has also written to the chief executive of the health board, raising this matter.
A spokesperson for Aneurin Bevan University Health Board defended the project, stating: "The solar canopy at The Grange University Hospital is part of a wider Welsh Government-funded Invest to Save programme, designed to deliver both financial savings and carbon reduction across our estate.
"The canopy will cost £3.3 million and is expected to generate around 645,000 kWh of electricity each year - the same amount as around 180 households' energy use.
"While the solar canopy element has a longer payback period of 19.7 years, the full programme of our energy-saving projects is projected to pay back within 11 years, with ongoing financial savings beyond that which will be used to support frontline NHS services."
"We are hugely grateful to Welsh Government for their investment in our energy-saving projects, which help the Health Board save money, reduce our carbon footprint, and continue focusing on delivering high-quality patient care."
The controversy surrounding this project highlights the ongoing debate about the best use of public funds, particularly in the context of a healthcare system already under significant pressure.