Expert Guides
In-depth analysis authored by our renewable energy specialists.
Agrivoltaics: the expert guide to combining farming and solar generation
Agrivoltaics is rewriting the relationship between energy and farming. Codified by France's APER law of March 2023 and the implementing decree of 8 April 2024, it lets farmers generate solar electricity while improving — not displacing — their agricultural output. This guide covers the regulatory definition, technology families (raised fixed canopies, single-axis trackers, retractable greenhouses), economics, CDPENAF procedures, and VoltWatt's field experience on vineyards, livestock farms and arable land.
Read guideCorporate PPA: the expert guide for buyers and developers
The Corporate Power Purchase Agreement has become the cornerstone of European corporate energy strategy. Faced with the end of regulated tariffs, GHG Protocol Scope 2 pressure and spot-market volatility, the buyer locks in a 10- to 20-year predictable price while securing Guarantees of Origin. For developers, a PPA underpins project bankability and cuts the cost of capital by 100–200 bps. This guide compares structures (physical, virtual, sleeved), gives 2026 reference prices and explains IFRS 16 / IFRS 9 treatment.
Read guideBESS: the expert guide to battery energy storage
Battery Energy Storage System became Europe's most-deployed flexibility technology in 2025, with 18 GW commissioned and a 65 GW cumulative projection by 2027. France's regulatory framework matured in 2024 with adjusted capacity market, fast aFRR market integration and the hybridisation tender. This guide covers technologies (LFP vs NMC, AC vs DC-coupled), revenue stacks, NFPA 855 fire safety, and standalone vs PV-hybrid economics.
Read guideHybrid plants: pairing PV, wind and storage to deliver dispatchable power
Hybridisation is the industrial answer to a brutal fact: peak renewable production rarely matches peak demand. Pairing PV, wind and BESS at a single point of connection turns an intermittent plant into a dispatchable asset capable of signing baseload PPAs, capturing capacity premium and avoiding price cannibalisation. France's CRE launched a dedicated tender in 2024; Germany and Spain followed. This guide explains why hybridisation became the 2026 standard, the architecture choices, and the economics versus standalone.
Read guideSolar project financing: the expert guide to bankability
A solar project becomes bankable only when its future cash flows convince lenders to fund 70–80% of CAPEX. This bankability rests on a handful of technical (DSCR, LLCR, debt sculpting), legal (EPC wrap, lender's technical advisor) and tax levers (tax equity, partial flip). This guide breaks down each, gives the 2026 European market ratios, and lays out VoltWatt's playbook for projects from 50 to 250 MW, greenfield to commissioning.
Read guideRepowering: extending and upgrading wind and solar assets
Repowering modernises a renewable plant reaching the end of its economic cycle. In wind, it replaces older turbines (1–2 MW, 70–80 m hubs) with modern ones (4–6 MW, 130–160 m hubs), often halving the count while doubling capacity and tripling output. In PV, repowering replaces degraded modules and inverters and restarts a 25-year cycle with PR up by 8–12%. This guide covers the technical, economic and regulatory options for 2026 operators.
Read guideSolar self-consumption: the expert guide for businesses and communities
Self-consumption is now the leading connection mode for new rooftop PV in France and Europe. Driven by sustained TURPE grid-fee increases, the end of feed-in tariffs on residential >9 kWp, and the 2024 decree extending the collective self-consumption perimeter to 20 km in rural areas, it is reshaping site-direct PV economics. This guide covers individual and collective self-consumption, the PMO role, surplus calculations and VoltWatt's industrial-site case studies.
Read guideTypes of solar panels: the 2026 technical comparison
In 2026, the PV module market consolidated around a few dominant technologies — TOPCon, HJT and a planned phase-out of PERC. Choosing the right module for a utility, agrivoltaic or industrial project is no longer a price-per-Wp question but a joint optimisation of efficiency, bifaciality, temperature coefficient and calendar degradation. This guide compares the four dominant families, gives 2026 efficiencies and explains VoltWatt's choices.
Read guideCRE tariffs: French open window and auctions explained for 2026
France's energy regulator CRE has run the tariff mechanisms underpinning PV economics since 2009. In 2026, the system rests on two pillars: the open window (S21 tariff revised quarterly) for small projects and the CRE auctions (PPE2 ground, rooftop, hybridisation, innovation, self-consumption) for projects above 500 kWp. This guide unpacks operations, 2026 prices, eligibility and VoltWatt's strategy by project size.
Read guideSolar ROI calculator: the expert method to value profitability
Computing solar project ROI rigorously needs more than a simple Wp/m² ratio. Profitability depends on a constellation: P50/P90 yield, calendar degradation, temperature coefficient, performance ratio, realistic OPEX, debt leverage, CPI indexation, sale or self-consumption tariff, and tax regime. This guide lays out VoltWatt's method used across 600+ MW of projects, gives 2026 assumptions by segment, and exposes pitfalls in DIY simulations.
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