Energy-as-a-service in Bulgaria: A techno-economic model of industrial PV + BESS contracts under the Post-RED III framework

Energy-as-a-Service (EaaS) shifts capital, operational, and performance risk for distributed energy resources from the consumer to a specialized provider, in exchange for a long-term fee indexed to delivered energy or to a measured outcome. In Bulgaria, the rapid deployment of photovoltaic (PV) plants and battery energy storage systems (BESS), together with the post-2023 regulatory reset (the Energy Act storage amendments, Ordinance No. 6/2024 on grid connection, transposition of RED III and the recast Energy Efficiency Directive), has opened space for EaaS structures behind the meter of industrial consumers. This paper builds a techno-economic model of a PV + BESS-as-a-Service contract for a mid-size Bulgarian manufacturer (5 MW peak load, 22 GWh annual consumption) served by a 4 MWp PV plant and a 2 MW / 4 MWh lithium-iron-phosphate battery. An hourly dispatch of PV generation against a three-shift industrial load feeds a 15-year cash-flow model at a 130 €/MWh service tariff. Under base-case assumptions (capex 4.18 M€, 8% discount rate, 150 €/MWh grid counterfactual), the provider earns a project IRR of 9.6% with an NPV of +0.44 M€, while the off-taker saves approximately 82 k€ per year at zero capex and books the fee as operating expense under IFRS 16. The outcome is most exposed to the service tariff, the discount rate, and capex: provider NPV turns negative below a 117 €/MWh tariff or above a 9.6% discount rate, and the off-taker's saving disappears if its all-in grid price falls to 130 €/MWh. EaaS is economically feasible in Bulgaria today, but the margin is thin, and the contractual and accounting infrastructure has not yet caught up with the technology.