here's another 2c to ponder...
I too used to use solar for my early game power, back when it used cables not circuits to build. Then, it was easily the best option in terms of automatic power generation - no furnace stoking, uranium mining, nothing but free power.
That all changed when solar plants upped the resource cost.
Some pros and cons of the Big 4:
Coal/Charcoal
Pros: A basic fuelburner is the cheapest EU generator you can build; fuel is plentiful (and in the case of charcoal renewable)
Cons: very low EU production
Geothermal
Pros: Low resource cost to build, high fuel/EU ratio, fuel is readily available, good source of mobile power
Cons: fuel can be difficult to source at the very beginning, limited EU generation
Solar
Pros: Automatic generation, infinite fuel
Cons: very low individual EU generation, must be visible to surface (and thus visible to other players)
Nuclear
Pros: high output, EU per fuel unit ratio is massive
Cons: extremely expensive to build, difficult to move, potentially incredibly destructive
I tend to build in that order; starting with coalburners til I can find a decent lava source (ie til I build a portal, or find a nearby lake), then using geos almost exclusively for mobile mining operations and remote recharge stations. My workshop/processing I run from geo until I can craft enough solar - I find that for a basic workshop of 2-3 macerators/recycler/compressor/electric furnace that approximately 12 or 14 solar panels feeding a pair of MFU's is quite sufficient. This generally lasts me until such time as I can craft a Nuclear plant, which I then use (for the most part) as a stand-alone power source for Mass Fabricators. I also run a circuit that allows me to use my nuclear plant to automatically top up my workshop power capacity.
We will gloss over my intense desire for the old, stackable IC coal/biofuel system to return - refillable fuel cans just render the whole process a waste of time and energy
Hope someone finds this useful