The report by auditors was to a finance committee meeting at the French senate last week.
It noted the spending on mechanisms to support renewables was estimated at €5.3 billion in 2016 and is set to grow in the future.
The vast majority of this spending (€4.4 billion) backed renewable electricity, while a total of €567 million went to renewable heat, although this sector is key to achieve France’s climate targets, according to the auditors.
The report said without a "clear strategy and stable and coherent support mechanisms, the French industrial fabric has had little benefit from renewables development".
It explained there is a disparity between cost, production volumes and share of different renewable sources in the energy mix.
Recent Eurostat data shows that France, Ireland and the Netherlands are furthest away from their 2020 renewable energy targets.
While the portion of renewables in final energy consumption has increased from 9.2% in 2005 to 15.7% in 2016, France still needs to achieve a 23% national target by 2020 and 32% target by 2030.
Ahead of the updating of France’s multiannual energy programme in 2018, the auditors said there should be a more "concerted and coherent energy strategy", with the calculation of costs associated to the development of an energy mix that meets the country climate targets and support mechanisms designed accordingly.
The parliament should be more involved in the process as well, auditors said.
Speaking at the French senate meeting, Jean-Louis Bal, president of French renewable energy association SER, said past commitments should be seen as an investment rather than just a cost, as they led to lower costs for renewables today and helped create jobs.