Grid fees are a major component of commercial and industrial site's energy costs, and a single quarter-hour peak sets the capacity charge for the entire year. However, a little-known rule in the grid fee rules (StromNEV) can offer significant savings.

Takeaways

1. Sites that stay out of the grid's peak windows can reduce their grid fees by up to 80%: With the atypical network usage scheme the capacity charge of the grid fees is billed on the highest site load inside the peak windows instead of the overall annual peak.

2. The grid operator sets these windows once a year: Each DSO calculates them per voltage level and season based on historic load data and publishes them by 31 October for the subsequent year.

3. Qualifying requires a significant load shift, which an optimised battery delivers: The peak inside the windows must sit at least 20% below the annual peak at medium voltage (30% at low voltage) and have an absolute difference of at least 100 kW.

4. The scheme ends with 2028, but larger sites can temporarily keep it until 2031: Under the current AgNes draft, sites averaging more than 10 GWh a year keep it if they have a valid agreement at the end of 2028 and meet the conditions at least once between 2026–2028.

1. Atypical network usage bills the capacity charge on the site's peak grid pull during the windows with highest network strain, not the overall annual peak

Grids are sized for the moment when all users draw power at the same time. A site whose own peak predictably falls outside that moment adds little to network stress. Under §19(2) sentence 1 StromNEV, the grid operator can offer these sites rebates. This works by changing when the capacity fee is counted. Instead of being charged on their absolute annual peaks, under atypical network usage, you pay only for the peaks during the periods with the highest historic grid stress. 

Every DSO calculates the peak windows (Hochlastzeitfenster) for each voltage level in their area from its historic load data and publishes them online by 31 October for the following year.

The windows only apply on working days. Weekends, public holidays, up to one bridge day per week and 24 December to 1 January never count. A season can have no window at all, and DSOs must cap them at a maximum ten continuous hours a day.

As a result, windows differ widely between grid operators and voltage levels. Their length matters as much as their timing, because it decides how much energy a battery must hold to sufficiently reduce the site's grid pull.

2. Sites only qualify with a significant shift and lose the rebate for any year they miss it

A site qualifies if its highest load inside the windows is sufficiently below its annual peak outside them. The minimum gap between the annual peak versus peak in the high load windows required to qualify depends on the voltage level.

Following steps are required to receive the rebates:

• Agreement: the site and its DSO sign an individual grid fee agreement, which typically takes effect on 1 January and runs open-ended.

• Notification: the site notifies the agreement to the Bundesnetzagentur by 30 September of the first year it applies.

• Annual report: by 30 June of the subsequent year, the site reports that it met the conditions.

The conditions are checked for each full calendar year, and if they are met, the billed peaks are only applied to what was measured during the DSOs peak load windows.

3. Atypical grid usage does more than cut the grid fee bill: it unlocks additional flexibility outside peak windows 

The benefits of atypical network usage go beyond lower grid fees and also changes how a battery can operate outside of peak load windows. Outside them, the site can draw as much as its grid connection allows without raising it, meaning it can use this headroom for:

• Load shifting: with a dynamic electricity tariff, the site moves flexible loads into the hours with the lowest prices, even if that would set a new annual peak. This can be used to discharge to the load and save on electricity procurement costs.

• Arbitrage: a battery charges from the grid when prices are low and discharges when they are high. The MiSpeL rules, finalised on 1 October 2026, let a C&I battery charge from the grid and feed the power back without paying grid fees and levies on the charged electricity. With this exemption, smaller price differences already pay off, so the battery can trade more often.

4. The scheme ends with 2028, but sites above 10 GWh can keep it temporarily until 2031

The StromNEV expires at the end of 2028, and atypical network usage ends with it. From 2029, the Bundesnetzagentur's new grid fee system AgNes applies. Its draft Festlegung keeps the atypical grid usage scheme until the end of 2031 only for sites that meet all three conditions.

The final AgNes decision is planned for the end of 2026, and the Bundesnetzagentur has indicated a separate decision in 2027 on what follows the special grid fees.

5. Now is the time to see what atypical grid usage could mean for your site, before the windows closes

Atypical network usage offers significant savings potential for C&I sites in 2027 and 2028 and will continue to do until 2031 for those above 10 GWh. Beyond this the scheme unlocks flexibility for sites outside the peak windows to reduce procurement costs via load-shifting and additional revenues for arbitrage with the grid fee exemption under MiSpeL rules. 

Capturing and leveraging the fullest potential of typical network usage requires more than just installing a battery. The site's load has to be forecast, charge held back for every window quarter-hour, and trading planned around the windows without breaking a threshold. 

Now is the time to assess the potential, as grid operators publish their 2027 windows by 31 October. 

Flexa optimises C&I batteries across these uses. Get in touch to see what a battery can deliver at your site, starting with your DSO's 2027 windows.