The steam dynamo, when using the steam generated by a steam solar boiler, doesn't produce as much RF at it should produce, and consumes all the steam incoming, whereas the steam produce by another steam dynamo with the augment is consumed properly and works fine

I'm not certain which version you're playing because you did not use our bug submission form, but given that you made a steam solar boiler it sounds like you're possibly playing the unofficial CEu port. This repository is for Nomifactory. Issues targeting Nomi-CEu should be filed on its repository: https://github.com/tracer4b/nomi-ceu.

If you are in fact playing an official version of the pack, my recommendation is to do what the quest book indicates and use a set of 1x boiler/ 2x turbine augmented steam dynamos, all at the same upgrade tier.

No I'm not using the unofficial and I did what the quest book recommanded but it uses solid fuel and I wanted to make a passive generation of power and I think it should work (some friends are playing the CEu and it works as intended)
Btw I'm playing on 1.2.2.1

Steam dynamos can be powered basically for free using sugar canes; as they have a burn duration they can also be used for furnace fuel. If you follow the quest line through LV a bit you will unlock a quest called "Snad" which gives advice on how to set up a fast sugarcane farm safely to avoid crashing your world with runaway item drops.

It should be noted that in 1.2.2.1, simply wrenching a redstone conduit onto a Snad block will cause it to rapidly grow any sand-based plant. In the development snapshots which use a newer version of EnderIO, this bug was fixed and you have to add a Sensor filter to reproduce the same behavior. In either case, the Snad quest suggests using a Timer from the mod DarkUtils for creating the redstone pulse that causes the plant growth effect. Anything that produces fast redstone pulses works, really.