1. You can harvest current-cycle solar, as captured or availed by PV, solar thermal, wind, hydro, (pipe dream / ineffective) wave energy, or biomass.
2. You can draw down an existing store of solar energy input deposited, with some inefficiency, as hydrocarbon fuels: coal, oil, gas (including methane hydrates, should you choose to go there).[2]
The difference is that in 1) you're deriving value from a continuing series of deposits, of approximately 84 terawatts,[3] or roughly 2,000 TWh (170 billion mtoe, 1 billion barrels of oil equivalent), an allowance shared with all other life-forms, and ecological / biospheric processes on the planet (we might care to consider those requirements before hiving of yet more for ourselves). The practical value derived remains a small fraction of the influx.
In the case of 2), you're spending down what is effectively an inheritance, at the rate of approximately 5 million times its initial rate of accumulation. This suggests that the spending-down is not particularly sustainable, even barring consideration of any other issues presented.
Of which I'm informed there are several.
The point remains that as you process that energy chain, each stage of the process leaves less useful or usable energy going out than came in, the balance being waste energy (entropy).
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Notes:
1. There's a very small contribution from non-solar sources, principally geothermal energy, a roughly 50-50 mix of gravitational potential energy of formation and radioactive decay, which could be considered sourced from the supernovae which enabled formation of the Solar System.
That's the 2nd law of thermodynamics.
Corollary: accounting of costs, prices, and values is badly flawed.