I recommend you the following literature:

http://www.eurelectric.org/media/180752/hydropower-final-lr-2015-2120-0003-01-e.pdf

Please read; Case study 5: Flexibility – Secure Electricity Supply, One Core Skill of Hydropower.

I hope I have been able to help you

Dear Ivan,

the answer to your question depends on the kind of hydro power system you have in place. Run-of-river only is quite different from a combination of small hydro combined with large hydro including pumped storage.

See also the following remark from a report on Brasil : "Existing reservoirs of hydropower plants are sufficient to balance variations in renewable electricity supply at an optimal mix of around 37% of PV, 9% of wind, and 50% of hydro power generation."

ftp://ftp.boku.ac.at/pub/repecftpg/repecftp/RePEc/sed/wpaper/572014.pdf

or you can have a look at the article :Exploiting existing dams for solar PV system installations (Progress in Photovoltaics Research and Applications 24(2):229-239 · February 2016)

Regards, Arnulf

Dear Ivan,

I agree with Arnulf,

You can investigate the Progress in Photovoltaics:Res.App, 24:229-239, Applied Energy 167:377-384, Renewable Energy 99:410-419.

There was a few publication. You can find it when you read this article.

I expect that these are help to us.

Best regards.