Solar Power Systems with Battery Storage: What Co-Location Means for Return on Investment, Self-Consumption, and Cost-Effectiveness

Market Analysis

March 20

Written by the Logic Energy Editorial Team

Co-location connects a photovoltaic system and a battery storage system behind a shared grid connection and increases the project's IRR by approximately 29%—through shared infrastructure costs, not through additional revenue.

The short answer

A co-located battery storage system connects the PV system and the storage unit behind a shared grid connection point—unlike a stand-alone storage system, which has its own connection. A white paper by 8Energies, enspired, and GOLDBECK SOLAR (February 2026) shows a relative increase in the project IRR of about 29% for new installations—rising from 8% to about 10% in the calculation example. The benefit stems primarily from shared infrastructure costs, not from additional revenue generated by the storage system. For businesses, the storage system reduces electricity costs through 60–80% self-consumption; for investors, it opens up additional sources of revenue.

A co-located battery storage system—the combination of a photovoltaic system and battery storage at the same location—has become a key differentiator in the German solar market by 2026. This article is aimed at companies seeking to reduce their electricity costs by installing their own PV system with storage, as well as investors who want to maximize the return potential of a combined PV-storage project—featuring concrete figures, up-to-date market data, and a clear overview of the regulatory window from 2026 to 2028.

A photovoltaic system without storage leaves money on the table today: Electricity fed into the grid at noon generates lower revenues than electricity that can be drawn during peak demand periods. While standalone PV systems will struggle with a declining solar capture rate and 573 hours of negative electricity prices in 2025, an integrated energy storage system turns precisely these market conditions into a structural advantage.

1. Market Data: 25.5 GWh Installed—and That's Just the Beginning

In short: By the end of 2025, Germany had approximately 2.22 million battery storage systems with a capacity of 25.5 GWh (MaStR / BSW-Solar). New installations in 2025 totaled 6.57 GWh (+8%). Large-scale storage systems are the growth segment—their share rose from 13% to 31%.

The German market for PV storage is growing faster than any other sector of the energy industry. Installed storage capacity has increased fivefold in five years. At the same time, more than 80% of all newly installed photovoltaic systems on single-family homes are already combined with solar storage—a clear sign that the market is mature.

The structural shift in new construction shows where things are headed (RWTH Aachen / ISEA, January 2026):

Segment	Expansion 2025	Change from 2024
Residential Storage (≤30 kW)	4.19 GWh	−6,4 %
Large-scale storage (>1 MW)	2.02 GWh	more than doubled
Commercial Storage (30–1,000 kW)	0.36 GWh	+47 %

This is due to a historical investment backlog. In November 2025, the Federal Network Agency reported approximately 400 GW / 661 GWh in grid connection requests for large-scale storage systems from transmission system operators alone; according to a BDEW survey, which includes distribution system operators, the figure exceeds 720 GW. In contrast, only 2.4 GW are currently in operation.

This bottleneck points to the real issue: grid connection. Available grid connection points are scarce, the grid connection approval process is protracted, and connections are often available to new projects only for a limited time. This is exactly where co-location comes in—it makes use of an existing grid connection for the generation facility. BSW-Solar estimates that the required storage capacity by 2030 will be around 100 GWh—four times the current level.

2. Co-location: Where the 29% project IRR comes from

In short: Co-location connects a PV system and a battery storage system behind a shared grid connection point. A white paper by 8Energies, enspired, and GOLDBECK SOLAR (February 2026) models a 20 MWp PV system with 10 MW / 20 MWh of storage and shows a relative increase in the project’s IRR of about 29%—from 8% to approximately 10% in the calculation example.

For new installations, the IRR advantage does not stem from additional revenue generated by the storage system, but rather from the shared infrastructure: grid connection, cable route, and substation are jointly funded through a cable-pooling model. With a design ratio of 1:1:0.5 (grid connection point to PV to storage), the PV project theoretically bears only about two-thirds of these costs. Self-consumption optimization and peak shaving are not included in the model: The modeled storage system is a “gray electricity” storage system that charges exclusively from the grid and is accounted for separately. The storage system also generates its own revenue from balancing energy and arbitrage trading between low- and high-price periods. We discuss the mechanics of arbitrage trading in detail in our analysis of PV-storage arbitrage returns.

New investments: relative increase in the project IRR of approximately 29%—from 8% to about 10% in the example calculation
Existing systems with retrofitted energy storage: +6–24% relative, depending on investment cost and revenue assumptions; based on 15%, this corresponds to approximately 16 to 19%
Unfavorable revenue scenario: only the infrastructure benefit of about 6% remains; under very unfavorable assumptions, the additional benefit disappears entirely
Revenue reduction due to the shared grid connection point: approximately 3.5–4%—this applies to the storage system compared to stand-alone operation, not to the PV system

The authors explicitly state that their figures are indicative. 8Energies, enspired, and GOLDBECK SOLAR are themselves active in the market for co-location projects: a primary source, but not an independent one.

3. Co-Location vs. Stand-Alone Battery Storage: Models and Use Cases

In short: A co-location storage facility shares its grid connection with a generation plant; a stand-alone storage facility has its own connection and operates solely on the market. Co-location saves on grid connections, space, and permits; stand-alone is more flexible but requires its own grid connection, which is in short supply.

Feature	Co-location storage	Standalone Storage
Power Connection	shared with the power plant	a close call of their own
Power source	Combined PV/wind power (green electricity)	Grid + Market (also Multi-Use)
Main Revenues	Self-Consumption, Peak Shaving, Arbitrage	Arbitrage, Balancing Power, System Services
Approval / Costs	bundled, more affordable	independently
Flexibility	linked to production	maximum

Stand-alone storage: Operated solely on the market

A stand-alone battery storage system does not feed its own solar or wind power into the grid, but rather generates revenue through battery trading: arbitrage on the day-ahead and intraday markets, as well as balancing energy (FCR, aFRR, and—increasingly important starting in 2026—the minute reserve). Stand-alone operation offers maximum flexibility but requires its own grid connection—and that is precisely where the bottleneck lies. As demand for grid-stabilizing system services continues to rise starting in 2026, the market environment remains attractive; however, revenues in individual markets fluctuate significantly and require active cross-market optimization by an experienced marketer.

Co-location Facilities: Storage for Solar or Wind Power

In co-location systems, the storage unit shares the grid connection with a generation facility—such as a PV system or wind turbines. The storage unit buffers excess electricity that would otherwise be fed into the grid at low or negative prices or curtailed, thereby avoiding curtailment losses. Sharing the grid connection optimizes its utilization and smooths out feed-in peaks—which stabilizes the local distribution grid. At the same time, the physical bundling of generation and storage reduces infrastructure and construction costs and minimizes the regulatory approval process. Where grid connection capacity is scarce, co-location is therefore often the most practical solution.

Green Energy Storage vs. Multi-Use: What the Storage System Is Allowed to Charge

The regulatory framework plays a key role in determining how flexibly a storage system can be used. A green electricity storage system may only draw electricity from renewable sources—it remains tied to the connected renewable energy generation facility, but in return ensures that facility’s eligibility for subsidies. Since the amendment to the Energy Economy Act (EnWG) (in effect since December 23, 2025), a multi-use or mixed-energy storage system may also draw a proportionate amount of grid electricity and assume additional market roles. This distinction is central to revenue planning: it determines which use cases and marketing channels are available.

Use Cases: When to Use Which Model

On-site consumption and peak shaving: Storage at the business premises (co-located with the rooftop or ground-mounted system)—for companies with high, consistent electricity demand.
Yield Optimization for Large Solar or Wind Farms: Co-location optimizes the marketing of the green electricity generated and boosts the IRR—for investor projects in the MW range.
Pure market and system services operation: Stand-alone storage—when a dedicated grid connection is available and no generation is to be integrated.

The choice of model is not purely a technical issue, but rather one of site selection and marketing. Site planning for co-located storage facilities takes into account not only the grid connection situation but also the accessibility of the site and environmental risks. Logic Energy, as a corporate group, provides all the necessary expertise—from site acquisition and grid connection planning to cross-market optimization—from a single source.

4. Six sources of revenue instead of one

In short: While a stand-alone PV system relies on one or two sources of revenue, a battery storage system opens up as many as six: self-consumption, peak shaving, and savings on grid fees as system revenues, as well as day-ahead arbitrage, balancing energy, and intraday trading as market revenues.

Sources of Investment Income

Self-consumption —a storage system increases the self-consumption rate from 20–35% to 60–80%. Every kWh consumed on-site saves the commercial electricity rate of 16–31 ct/kWh (BDEW / wattline, February 2026)—roughly 2–4 times more valuable than the EEG feed-in tariff of 7.70 ct/kWh (partial feed-in up to 10 kWp, effective August 1, 2026).
Peak shaving —with a power price of 80–200 EUR/kW/year and a peak reduction of 300 kW, this results in annual savings of 24,000–60,000 EUR. Typical payback period: 3–5 years.
Grid Fee Exemption (Section 118(6) of the Energy Industry Act (EnWG))—Storage systems commissioned by August 2029 are exempt from grid fees on purchased electricity for 20 years. This exemption applies under current law; the Federal Network Agency may adopt different regulations (Section 118(6), sentence 12, of the Energy Industry Act (EnWG)).

Revenue Sources from Trading and Balancing Energy

Day-Ahead Arbitrage —the ISEA Battery Revenue Index (RWTH Aachen) does not report arbitrage separately but includes it in the cross-market result; for a 2-hour system with two cycles per day, this stood at approximately 215,400 EUR/MW/year based on a rolling 365-day average (as of August 18, 2026).
Balancing energy (FCR + aFRR) — combined: approximately 179,000 EUR/MW/year (enervis BESS Index / pv magazine, 2025/2026).
Intraday trading and instantaneous reserve —the cross-market result of the ISEA Battery Revenue Index (FCR + aFRR + arbitrage) stood at approximately 215,400 EUR/MW/year as of August 18, 2026; the index is updated daily, and there is no fixed annual value.

5. Technology: LFP, Efficiency, and Battery Management System

In short: Commercial energy storage systems rely almost exclusively on LFP cells: high safety, >10,000 charge cycles, system prices around 108 USD/kWh (BNEF, December 2025), and 92–95% round-trip efficiency. A battery management system monitors each cell and controls charging, discharging, and balancing power.

LFP vs. NMC: Which cell chemistry is best for commercial storage systems?

Lithium iron phosphate (LFP) is the industry standard for stationary commercial applications: no thermal runaway (high safety), >6,000 to >10,000 charge cycles at 80% remaining capacity, stable operation between −20 °C and +60 °C, lower-cost raw materials (no cobalt), and a round-trip efficiency of 92–95%. BNEF reports system prices of $108/kWh (December 2025)—a 45% decrease compared to 2024.

NMC (Lithium-Nickel-Mangan-Kobalt) bietet höhere Energiedichte, hat aber geringere Zyklenlebensdauer (~3.000-5.000) und höhere Kosten durch Kobalt - in Großspeichern kaum noch relevant. Blei-Säure-Batterien spielen mit ~80 % Wirkungsgrad und <1.000 Zyklen keine wirtschaftliche Rolle mehr.

Efficiency: What is lost during charging and discharging

In modern LFP systems, the round-trip efficiency is 92–95%—out of every 100 kWh of solar power charged, 92–95 kWh are available again. With 365 charging cycles per year and a capacity of 1,000 kWh, annual losses amount to approximately 18,000–29,000 kWh. The inverter’s DC/AC efficiency is 97–99%; thermal management can reduce efficiency by 2–5 percentage points in warm environments.

Battery Management System (BMS): The brain of the storage system

The BMS monitors the voltage, current, and temperature of each cell and protects against overcharging, deep discharge, and short circuits; thermal management and fire protection are key safety factors in the operating concept. It handles cell balancing, state-of-charge (SoC) and state-of-health (SoH) estimation, and communication via CAN bus, Modbus, and SunSpec. Integrated into the higher-level energy management system (EMS), it controls charging and discharging. EERA Consulting (October 2025) documented that active cross-market optimization resulted in revenues up to 243% higher than with passive systems.

Smart Meters and Communication

As of June 1, 2026, all new PV systems with a capacity of 7 kW or more are required to have a smart meter (Solar Peak Act, in effect since February 25, 2025)—previously, the threshold was 25 kWp. The smart meter enables remote power curtailment (Section 14a of the Energy Industry Act), dynamic grid fees, and a transparent billing basis. For investors, it serves as an enabler for dynamic tariff models that can increase storage revenue by an estimated 3–8%.

6. Components of a Photovoltaic System with Storage

In short: A PV storage system consists of battery cells, a storage inverter, and a battery management system, along with wiring and an energy management system. Together, these components form an integrated system that generates, stores, and delivers solar power as needed.

Lithium-ion batteries: The heart of energy storage

The battery cells are the most expensive component. Key specifications for commercial LFP systems: typical storage capacity per module of 50–250 kWh, >10,000 charge cycles at 80% residual capacity, service life of 10–15 years, system price of $108/kWh at the cell pack level (BNEF, December 2025). For most co-located PV projects (2-hour systems, C-rate 0.5), lithium-ion batteries are the superior choice; turnkey system prices per kWh decrease significantly as system capacity increases.

Battery-backed inverters: Connecting the PV system to the power grid

The storage inverter serves as the interface between the PV system, the battery storage, and the grid, handling AC/DC conversion, MPPT, grid forming (off-grid operation), and grid connection. Bidirectional inverters are predominantly used for commercial systems; their DC/AC efficiency ranges from 97% to 99%. Costs range from 50,000 to 200,000 EUR per power class (100 kW to 5 MW); in co-location projects starting at 1 MWp, inverters account for approximately 10–15% of the total investment.

Solar panels: Generating solar power

PV modules convert sunlight into electricity. High-efficiency monocrystalline modules are the most common choice for commercial systems: efficiency 21–23%, rated power 550–700 Wp, service life 25–30 years (80% of rated power after 25 years), degradation of ~0.3–0.5% per year, system costs (ground-mounted) 750–1,000 EUR/kWp. Bifacial modules generate 10–25% more energy on light-colored surfaces. For more on this specific system type, see our page on agri-PV.

Installation and Commissioning

The installation includes foundation work, module installation and DC cabling, setup of the storage containers, AC-side installation (grid connection, protective devices in accordance with VDE 0100), commissioning and parameterization (EMS/BMS, smart meter gateway), as well as handover of the grid connection and MaStR registration. The installation time for a 500 kWp + 400 kWh system is 4–8 weeks after approval; for multi-MWp ground-mounted systems, a construction period of 3–6 months should be planned.

7. Sizing: How large does a commercial PV storage system need to be?

In short: System sizing is based on the following targets: 0.8–1.2 kWh per kWp of PV for self-consumption, 20–40% of the peak load for peak shaving, and a C-rate of 0.5–1.0 for arbitrage. A site-specific design based on the actual load profile is always required.

Guidelines for Commercial PV Storage Systems

Self-consumption: 0.8–1.2 kWh per kWp—500 kWp PV → 400–600 kWh of storage; self-consumption rate 60–80%.
Peak Shaving: Storage capacity = 20–40% of the peak load to be shaved; capacity = power × duration (15–60 min.).
Arbitrage / Revenue Stacking: C-rate 0.5–1.0 – 10 MW → 10–20 MWh (reference model from the 8Energies white paper).

Typical system sizes and investment costs by segment

Commercial PV system with storage (200–1,000 kWp): Annual generation ~180,000–900,000 kWh; recommended storage capacity 160–1,000 kWh; PV system costs (rooftop) 750–950 EUR/kWp; total investment for a rooftop system with storage 300,000 EUR–1.5 million EUR.

Industrial / ground-mounted PV with co-located storage (1–20 MWp): Storage capacity 1–20 MWh; total investment in PV + storage starting at ~5 million EUR. The specific system costs per kWh depend heavily on size and configuration and decrease significantly as the system size increases.

Which C-rate for which purpose?

C-Rate 0.25 (4h): Day-Ahead Arbitrage, Long Load Shifting.
C-Rate 0.5 (2h): Market standard for co-location—a balance between arbitrage and FCR.
C-Rate 1.0 (1h): FCR and short-term intraday peaks.
C-Rate 4.0 (15 min.): FCR prequalification.

Retrofitting vs. Redesign

A storage system planned from the outset is significantly more cost-effective than a retrofit: joint grid connection planning saves 50,000–150,000 EUR, inverter sizing can be optimized, permitting processes run in parallel, and the building code exemption (Section 35(1)(11) of the German Building Code (BauGB)) applies only if there is a spatial and functional connection. For existing systems with connection reserve capacity, the 8Energies white paper nevertheless estimates the IRR uplift at +6–24%.

8. For Businesses: Self-Consumption, Self-Sufficiency, and a 3-5 Year Payback Period

In short: A PV storage system increases the self-consumption rate from 20–35% to 60–80% and reduces grid fees through peak shaving. Payback periods of 3–5 years are realistic with peak shaving, compared to 6–10 years for PV systems without storage.

Total PV self-consumption in Germany rose from 3.55 TWh (2020) to 12.28 TWh (2024)—17% of net PV generation (Fraunhofer ISE, December 2025). Achievable figures: Self-consumption rate from ~25% to 60–80%; grid procurement can be reduced by 35–55 percentage points; electricity costs (16–31 ct/kWh for commercial electricity) can be reduced by thousands to hundreds of thousands of euros annually; self-sufficiency of 40–60% of annual electricity demand.

Peak Shaving: The Underestimated Lever

Companies pay a capacity charge based on their annual peak load—typically 80–200 EUR/kW/year. A manufacturing facility (800 kW → 500 kW) saves approximately 24,000 EUR/year at 80 EUR/kW; for a large consumer (2,000 kW peak load, 200 EUR/kW), grid fee savings of up to 400,000 EUR/year are possible.

Payback Periods Compared

Constellation	Payback period
Commercial - PV Storage with Peak Shaving	3–5 years
Commercial - PV + Storage (without peak shaving)	5–8 years
Commercial - PV only (without storage)	6–10 years

Businesses planning to install their own PV system with integrated energy storage can find more information about project and financing models on the page " Your Own PV System for Your Business."

9. The Regulatory Window: 2026–2028

In short: Three factors define this timeframe: The grid fee exemption (Section 118(6) of the Energy Industry Act (EnWG)) runs through August 2029; the declining depreciation rate of 30% for storage systems ends on December 31, 2027; and the 2027 EEG reform continues to put pressure on standalone PV systems without storage.

Exemption from grid fees (Section 118(6) of the Energy Industry Act)

The incentive applies to storage facilities that become operational within 18 years of August 4, 2011; the deadline is in August 2029. “Commissioning” is defined as the first draw of electricity for trial operation (Section 118(6), sentence 6, of the Energy Industry Act (EnWG)).

The exemption applies only to grid fees in the narrow sense, i.e., the transmission and capacity charges. It does not apply to statutory surcharges, the concession fee, metering point operation and billing, the electricity tax, or the construction cost subsidy (Federal Court of Justice, decision of June 20, 2017—EnVR 24/16). The value of the exemption in individual cases depends on the voltage level, grid area, and duration of use, and cannot be quantified on a flat-rate basis.

Regulatory reservation. The 20-year exemption is stipulated in the law, but does not constitute a guaranteed basis for calculation over the entire term. Pursuant to Section 118(6), sentence 12 of the Energy Industry Act (EnWG), the Federal Network Agency may adopt provisions that deviate from sentences 1 through 11—including, expressly, with respect to the temporal scope of application. This requires a determination procedure under Section 29(1) of the Energy Economy Act (EnWG); such a procedure is currently underway under file number GBK-25-01-1#3 (AgNes). In this proceeding, the Federal Network Agency has characterized the full exemption as not cost-reflective. There is no statutory grandfather clause, nor is there any case law on the issue of protection of legitimate expectations; in any case, the specialized literature considers it difficult to justify a legitimate expectation, at least for new installations . Treat the exemption as a bonus, not as a planning basis guaranteed for the entire term.

The exact deadline has not been uniformly specified: According to the calculation of the deadline under Sections 187(2) and 188(2) of the German Civil Code (BGB), the deadline ends at the close of business on August 3, 2029; documents from the Federal Network Agency cite August 4, 2029. There is no judicial clarification on this matter—those planning down to the exact day should use the earlier date.

KraftNAV Exemption and Grid Integration

Since December 2025, battery storage systems have been exempt from the complex KraftNAV procedure; co-located storage systems benefit from the priority connection granted to renewable energy installations under Section 8 of the EEG. Conversely, systems with a capacity of 100 kW or more—both generation facilities and storage systems—are integrated into the grid operators’ congestion management system via Redispatch 2.0. For co-location, this means that the storage system can smooth out feed-in peaks and actively contribute to system stability and to relieving the load on the distribution grid.

Special Provisions Under Building Law (Section 35(1)(11) of the German Building Code (BauGB))

Co-located storage facilities that are spatially and functionally connected to an existing renewable energy plant are granted special status under building codes for outdoor areas—no zoning plan is required. This significantly speeds up the permitting process for open-space facilities.

EEG 2027: Fixed feed-in tariff no longer applies to new installations

On July 29, 2026, the Federal Cabinet approved the government’s draft of the EEG 2027 along with the grid connection package. For new photovoltaic systems, the fixed feed-in tariff is to be eliminated and replaced by a time-limited transitional payment; direct marketing will become the norm. The draft is not yet legally binding—the Bundestag and Bundesrat will deliberate on it after the summer recess, and it is scheduled to take effect on January 1, 2027. Systems that go into operation by the end of 2026 will retain their guaranteed 20-year feed-in tariff. For pure PV systems without storage, this increases the risk of revenue loss and curtailment—a further incentive to integrate solar storage from the outset. Details can be found in the guide to EEG feed-in tariffs for 2026.

10. Tax Benefits: 30% declining-balance depreciation for battery storage systems

In short: As of July 1, 2025, a declining balance depreciation rate of 30% (three times the straight-line rate) applies to battery storage systems, effective through December 31, 2027. With the IAB and special depreciation, a significant portion of the investment can be claimed in the first one to two years.

The Act to Strengthen Germany as a Business Location (approved by the Bundesrat in July 2025) raised the declining-balance depreciation rate under Section 7(2) of the Income Tax Act (EStG) to three times the straight-line rate, up to a maximum of 30 percent.

Battery storage (useful life: 10 years): declining-balance depreciation of 30% (3 x 10%), valid from July 1, 2025, through December 31, 2027.
Solar power system (useful life of 20 years): declining-balance depreciation of 15% (3 × 5%, Section 7(2) of the German Income Tax Act (EStG)).

The investment deduction (50%, Section 7g(1) of the Income Tax Act), special depreciation (40%, Section 7g(5) of the Income Tax Act), and declining-balance depreciation may be combined. Depreciation on a declining-balance basis is calculated in the year of acquisition on the full tax base reduced by the investment deduction; the special depreciation reduces the remaining book value only in subsequent years. This results in a large block of expenses in the first one to two years—the exact amount depends on the individual situation. See the article on “Saving on Photovoltaic Taxes in 2026” for details.

Note: The tax implications depend on your individual tax situation. You should consult a tax advisor to determine whether this applies to you.

11. Are there any incentive programs for PV storage systems?

In short: Yes—the KfW 270 loan (up to 150 million EUR, with an effective interest rate starting at around 3.8%), state incentive programs, the EEG market premium, innovation grants, as well as grid fee exemptions and tax depreciation. Applications for several of these programs must be submitted before purchasing the system.

KfW Loan 270: Financing for PV Systems and Storage

The KfW program “Renewable Energies – Standard” (270) is the most important financing instrument for commercial PV systems. Loan amounts of up to 150 million euros per project, terms of 5 to 30 years with grace periods, interest rates starting at approximately 3.8% effective, depending on creditworthiness and term (best credit rating; KfW publishes daily updated terms as of August 2026), with a financing ratio of up to 100% of eligible costs. Eligible costs include solar systems, battery storage, inverters, installation, and grid connection. Applications must be submitted through the borrower’s primary bank before construction begins.

State-level incentive programs for energy storage systems

Several federal states offer subsidies for the purchase and installation of energy storage systems: Bavaria (BayernLabo and regional programs), Baden-Württemberg (L-Bank Environmental Loan Program), Thuringia, Saxony, and Brandenburg (investment grants from state development agencies). The grants can range from several hundred to several thousand euros; most programs require an application to be submitted before the purchase, and funds are often exhausted quickly.

Compensation, Market Premium, and Bids

EEG Market Premium: Solar systems of 100 kW or more receive a sliding-scale market premium through their direct marketing partner. The EEG feed-in tariff for systems up to 100 kW is 7.70 ct/kWh (partial feed-in up to 10 kWp, effective August 1, 2026, valid through January 31, 2027). Read more in the article on the 2026 EEG feed-in tariff.
The Federal Network Agency's innovation tenders specifically promote combinations of renewable generation and storage facilities—which is relevant for co-location projects in the tender segment.
Declining-balance depreciation and IAB: A significant portion of the investment in storage is tax-deductible in the first few years.

Conclusion: Plan for co-location from the very beginning

Today, storage is no longer just an add-on—it’s an integral part of the return-on-investment structure. As a group of companies, Logic Energy designs and builds combined PV-storage systems as a one-stop solution—from site analysis and land acquisition to ongoing operations. Whether you’re an investor interested in a co-location project, a business looking to reduce electricity costs with your own PV system, or interested in the current EEG feed-in tariff or tax incentives: Contact us—we’ll calculate your individual potential free of charge.

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This article is intended solely for general information purposes and does not constitute investment, tax, or legal advice. Return figures are based on historical data from the Helm Group and on cited third-party market studies; they are not a guarantee of future results. Technical specifications are approximate and depend on the product, operation, and location. For your specific situation, please consult a licensed financial or tax advisor. Legal provisions and procedures are current as of August 2026 and are subject to change; ongoing regulatory proceedings, such as AgNes (Federal Network Agency), may alter the framework conditions described. All information is provided without warranty. As of August 2026.

FAQ

What does "co-location" mean in the context of battery storage systems?

Co-location refers to the shared use of a grid connection by a battery storage system and a generation facility downstream of a grid connection point. According to a white paper by 8Energies, enspired, and GOLDBECK SOLAR (February 2026), this increases the project IRR of a new facility by approximately 29%—primarily because both systems share the connection infrastructure.

What is the difference between colocation and stand-alone storage?

A co-location storage system shares its grid connection with a solar or wind power plant and buffers the electricity generated by it. A stand-alone storage system has its own grid connection and is operated solely through the market and via system services, without any coupled generation. Co-location saves on grid connection costs, space, and the effort required to obtain permits; stand-alone systems are more flexible but require their own grid connection, which is in short supply.

Is a solar storage system worth it for a commercial business?

Yes, under the right conditions. A storage system increases the self-consumption rate from 20–35% to 60–80% and reduces expensive peak loads through peak shaving (power price: 80–200 EUR/kW/year). Payback periods of 3–5 years are realistic with peak shaving. The key is to design the system to match the facility’s actual load profile.

What return can a co-located solar storage system generate?

The white paper by 8Energies, enspired, and GOLDBECK SOLAR (February 2026) shows a relative increase in the project IRR of approximately 29% for a new plant—from 8% to about 10% in the sample calculation. This benefit stems from shared infrastructure costs and is described by the authors as indicative. Return figures are based on historical data and are not a guarantee of future results.

Does the grid fee exemption also apply to co-located storage facilities?

Yes. The exemption under Section 118(6) of the Energy Industry Act (EnWG) applies to storage facilities commissioned by August 2029, regardless of whether they are co-located or standalone. The Federal Network Agency is revising the grid fee system as part of the AgNes process: The draft determination dated August 6, 2026, aims to limit the exemption to facilities for which a final investment decision was made before January 1, 2027.

What is the difference between LFP and NMC in PV storage systems?

LFP (lithium iron phosphate) is the standard for commercial storage: >10,000 charge cycles, high safety, lower-cost raw materials, and system prices of around 108 USD/kWh (BNEF, December 2025). NMC offers higher energy density in a smaller footprint but has lower cycle life (~3,000–5,000) and higher costs due to cobalt. For stationary PV storage, LFP is almost always superior.

How many sources of revenue does a solar storage system have in Germany?

Up to six. Three are installation-related: optimization of self-consumption (60–80% rate compared to 16–31 ct/kWh for commercial electricity), peak shaving (80–200 EUR/kW/year), and the grid fee exemption under Section 118(6) of the Energy Industry Act (EnWG). Three are market revenues: day-ahead arbitrage, balancing energy (FCR/aFRR), and intraday/instantaneous reserve.

When does the 30% declining balance depreciation for battery storage systems end?

The 30% declining balance depreciation under Section 7(2) of the Income Tax Act (EStG) is limited in time until December 31, 2027. For investments capitalized after that date, the provision will no longer apply unless extended by law. A tax advisor should verify whether this provision applies in individual cases.

References

All information is provided without guarantee. As of August 2026.

Logic Energy Editorial Team https://www.logicenergy.de/