Pros
you can learn a good deal of how the energy sector operates
Cons
The company is a very small player in the industry. It struggles to make profits and the growth of the company is mediocre at best compared to other companies. The management will try to convince you the opposite, but in the last 5-6 years the size has stayed the same. The profitability has improved only because they have learned to manage the workforce differently, meaning - every time the numbers are dissatisfying to managers and investors, the company sheds bunch of employees.
The opportunity to grow within the company is low - you can move one level up if you are entry level or one level above the entry level, but for higher positions - they hire from outside. Because of all that, the moral is very low and there is a clear divide between the higher position and the lower ones. There is absolutely no respect of the executives and the higher positions towards the lower level employees.
My advise to everybody considering starting with Prenova is do it only if there is no other alternative and if you start with the company, keep looking for another job.