Renewable electricity is now routinely the cheapest source of bulk energy — but bulk energy is not what industrial offtakers, grid operators and electrolyser developers actually buy. They buy power that is there when they need it.
So we asked two questions: which architecture delivers firm power most cheaply, and how does that cost compare with the fossil generation it is meant to displace?
01 / THE HEADLINEWhat firm power costs at this site
Costs are reported as delivered LCOE — lifecycle cost divided by the energy actually delivered to the customer, after curtailment. All designs share the same resource data and financing basis: 12% WACC, 70/30 debt at 8.5%, 30-year life.
02 / THE FINDINGSThree findings stand out
To serve ~90% of a flat 100 MW load, the wind–solar–battery hybrid delivers power at about $80/MWh — roughly 27% below the best wind+battery design ($110) and 55% below the best solar+battery design ($176). The gap widens as the reliability target rises, and only the hybrid can reach effectively complete coverage.
Because solar generates nothing at night, a solar+battery plant must both massively over-build and cycle every delivered evening and overnight megawatt-hour through batteries — paying twice. It cannot economically pass ~99% coverage at all.
The ~90% hybrid at $80/MWh sits below a new combined-cycle gas plant burning imported LNG (~$100–115/MWh), and 2–6× below the open-cycle turbines and diesel gensets currently being built. Fuel is 45–90% of the fossil number and none of the renewable one.
03 / THE SITEWhy this site makes the case
The case-study site is on the Atlantic coast of southern Morocco, in one of the world's premier overlapping wind and solar belts. Two features decide every result that follows.
That six-hour offset does a large share of the firming work batteries would otherwise have to do — and it is the single biggest reason the hybrid beats either single-resource design.
04 / THE CURVEFirmness is a dial, and it has three regimes
Reliability does not get expensive gradually. It gets expensive in steps, as each successive mechanism runs out of road.
Reliability is obtained almost free by letting the natural anti-correlation of wind and solar fill the day. Wind's night-time output carries coverage into the high 80s; a first slice of solar fills the afternoon trough — no battery earns its place yet.
Each additional point of coverage is bought with surplus generation that is increasingly curtailed — 40–60% of everything generated is thrown away on purpose, because over-building cheap wind and solar still beats storing energy for the gap hours.
The residual gaps are long, wind-still, overcast stretches that only deep storage can bridge. Storage utilisation — and therefore value — collapses, and the last fraction of a percent of reliability is effectively unbounded in cost.
"At this site the hybrid serves 90% of a constant industrial load for $80/MWh delivered. The last nine points of reliability cost as much again as the first ninety."
Reliability is a priced product, not a free extra. Sellers should not give firmness away inside an energy-only price — the marginal cost of the last ten points of coverage is real and large. Buyers should not pay for 99% when 90% will do, and should say which they need before the plant is sized.
05 / THE FULL PAPERMethod, model and the numbers behind every chart
The full white paper sets out the resource assessment, the delivered-LCOE method, all three candidate architectures, the complete cost-of-reliability curve, the fossil benchmark on mid-2026 fuel costs, and the required-PPA analysis for bankability.
Converge Hybrid white paper · June 2026 · PDF