The Welsh Government is providing funding worth more than £7 million to boost green growth in the country.
Monmouthshire Council has been granted £4.5 million for the Oak Grove Solar Farm, which has the potential to generate enough green power for 1,400 homes.
The project is expected to save more than 2,000 tonnes of carbon emissions a year.
Flintshire Council is receiving £3.13 to upgrade 11,000 street lights to LED equivalents, which it hopes will help save £360,000 as well as more than 1,300 tonnes of emissions annually.
Incomes and savings generated from both projects will be used to repay the investment, support local community projects and leave the councils with a net income.
Welsh Environment and Rural Affairs Secretary Lesly Griffiths said: “Through our Green Growth Wales Initiative, we are supporting the development of public sector energy efficiency and renewable energy projects.
“These projects have huge potential and all public bodies should be developing green growth projects like this to deliver decarbonisation in Wales.”
An environmental permit application for a proposed waste treatment facility in Wales was rejected earlier this year.