Second-Life Energy Plants: What Happens to PV, Biogas, and Wind Assets After EEG Support Ends?
Every PV, biogas, and wind plant that came online under Germany's EEG eventually faces the same moment: the 20-year remuneration period ends. From that point on, continuing to feed in at the market price alone is often below breakeven, and dismantling a working plant is expensive and wasteful. But an expiring subsidy isn't a dead end — it's a decision point, and plants that plan for it ahead of time keep far more options open than plants that wait.
Three ways to keep a plant's grid connection working for you
Across PV, biogas, and wind, the technical toolkit for a plant reaching this point comes down to the same three structural models. The difference between them is how storage and generation share, or don't share, the site and the grid connection.
Hybrid power plant — generation and storage are integrated and optimized together as one system, typically built in from the start or added through a deep retrofit.
Co-location — storage and generation share site synergies, above all the grid connection, but operate independently of each other. This is usually the fastest, least disruptive path for an existing plant, since it reuses a connection point that's already approved rather than requiring a new one.
Stand-alone — an independent storage system, not coupled to any generation asset. This fits when a site's generation equipment is being retired but the location and connection still have value on their own.
For most PV and biogas sites approaching EEG expiry, co-location is the natural starting point. It works with the plant you already have, keeps the existing connection in use, and adds a second, storage-driven revenue stream without touching the generation asset itself. We covered exactly how that works for PV plants, including the revenue mechanics, in our post on turning a PV plant's existing grid connection into a second revenue stream. The same co-location logic applies directly to biogas sites too, with one added advantage.
Biogas plants have an extra lever: flexible generation
Unlike solar or wind, biogas generation is already dispatchable: a biogas plant can ramp its output up or down to follow demand rather than being at the mercy of the weather. Pairing that flexibility with battery storage adds a second lever on top of the first. The plant can shift when it generates, and the battery can shift when it exports, giving a biogas site more ways to capture value from swings in the power price than a purely weather-dependent asset has. That's also why getting the most out of a biogas site is often less about a single fix and more about combining flexible generation with the right storage configuration for that site, using the same hybrid, co-location, and stand-alone models described above.
Grid balancing value is rising as renewable share grows
There's a broader trend behind why this matters now. As wind and solar make up a larger share of the grid, the value of dispatchable flexibility, meaning plants and storage systems that can shift output to match demand, tends to rise with it. A plant that can flex, whether through storage, flexible generation, or both, is positioned to capture more of that value than one that can only run at the mercy of the weather or a fixed feed-in schedule.
Timing is the real decision, not the technology
The three models above are all viable. What actually determines the outcome is when a plant operator starts planning. Sorting out role allocation, engineering, and permitting for a co-location or hybrid system takes time, and a plant that waits until its EEG support has already lapsed risks a period where its grid connection sits idle and revenue drops to bare market-price feed-in with nothing to offset it. Plants that start the conversation before expiry keep every option on the table, including which structural model fits and who takes on which role in the partnership.
Is this a fit for your plant?
If your PV, biogas, or wind plant is approaching the end of its EEG remuneration, the earlier you start planning its second life, the more options you keep. Get in touch with Greenbox Energy Solutions, or go directly to the page for your asset type: PV plant operators can find storage options on our PV Co-Location page, and biogas plant operators on our battery storage for biogas plants page.
Stay in the loop: follow Greenbox Energy Solutions on LinkedIn for updates on new projects and offerings, or connect with our CEO, Dr. Henning Heppner, on LinkedIn.
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