The cable overload protection the standard requires — tested, high-performance, available for licensing today.

For manufacturers of plug-in storage systems

Your devices promise maximum self-consumption. The bottleneck is not the size of your battery, it is the interface to the customer’s house wiring. ready2plugin opens that interface — the only technology tested by the Fraunhofer Institute for Solar Energy Systems ISE within the DKE standardisation project.

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Understand the blind zone

1,075 → 22,770 kWh / year

Usable feed-in corridor

with dynamic cable overload protection1

up to 80 %

Self-consumption

single-family home, up to 7,000 kWh annual demand1

up to 10,000 Wp

through a domestic socket

equivalent to 20 modules / 10 kWp

until 2038

patented in eight countries

DE · FR · UK · CH · USA · BR · CN · IN3

Why this requirement has been overlooked

The gap does not appear in any of your certification procedures.

No single requirement is missing. What is missing is the consolidation of the distributed requirements into one product standard against which you could have your plug-in storage device certified.

Cable overload protection under DIN VDE V 0100-551-1 (protection equation Iz ≥ In + Ig) applies to plug-in storage systems and to installations above 960 Wp. But it is not part of any closed certification procedure — and therefore not part of the one document your engineers work through for the declaration of conformity.

The product standard for plug-in storage systems is expected to take another two to three years. Until then there is no procedure to certify against, and without a harmonised standard there is no presumption of conformity. The full safety analysis for cable overload protection rests with you: your own risk assessment, your own evidence, your own liability.

Against this background, it is understandable that the requirement was overlooked in the first generation of devices.

The mechanism in one paragraph

The critical heating does not occur at the plug contact. It occurs in the conductor.

A standard circuit breaker only measures the current coming from the distribution board — not the additional current fed in within the same circuit. When a storage system feeds in continuously, the breaker sees the difference between load and feed-in, while the conductor carries the full sum. We call this the blind zone; internationally it is known as breaker masking.

Within this zone the breaker loses its protective function: the conductor can be operated above its permissible continuous temperature of 70 °C without the breaker tripping. PVC insulation then ages in fast motion — statistically from around 20 years at 70 °C down to roughly one year.

Iz ≥ In + Ig

Iz = current-carrying capacity of the conductor · In = rated current of the protective device · Ig = rated output current of the storage system (DIN VDE V 0100-551-1)

The issue is not the device in isolation. It arises in the customer’s final circuit — exactly where your product testing ends and the house installation begins.

The full derivation — measurement series, calibrated temperature model and normative references — is set out in our article Cable protection explained: the blind zone in socket feed-in (German) →

What ready2plugin delivers

One technology that closes exactly this gap — independently tested by the Fraunhofer ISE.

Once you have understood the problem of socket feed-in, you will see that ready2plugin is the best way to deliver the maximum amount of energy to your customers.

Because every time you feed in energy, you also create a potential cable hazard — without protection you would have to shut down at precisely the moment when the circuit is under heavy load. The ready2plugin thermal model resolves this conflict: it keeps serving high load demands over long periods instead of throttling as a precaution.

A real-time thermal model, not simple current limiting

ready2plugin converts the measured currents in the final circuit into a thermal model of the cable. It is this temperature model — exploiting the thermal inertia of the house wiring — that makes it possible to transmit this level of power through an ordinary domestic socket at all, while keeping the conductor within its permissible 70 °C. The protection equation Iz ≥ In + Ig is satisfied. This conversion is the patented core of the ready2plugin technology.

Independently tested

Developed on the basis of more than 300 measurements taken in real installations. Function and fail-safe behaviour were tested by the Fraunhofer Institute for Solar Energy Systems ISE within the DKE standardisation project, which confirmed the system was „praxisnah erfolgreich getestet“ — successfully tested under realistic conditions.2

Patent-protected, but open to you

Our algorithms are patented in eight countries (DE, FR, UK, CH, USA, BR, CN, IN). The underlying task — cable overload protection for storage systems feeding in through a socket — is not. A licence gives you the tested solution instead of funding an in-house development that carries patent risk. Outside those eight countries you are free to use the indielux technology.3

Three routes to integration

Into your product line without hardware redesign.

Software update

ready2plugin inside

Integration into existing energy storage systems via firmware, with no change to the hardware. Available to selected, trusted partners only.

★ Recommended

Interface

Cloud SaaS API

Feed-in control through our cloud interface — the recommended route for a fast start with minimal integration effort.

Retrofit

ready2plugin Stromwächter

External hardware for existing devices and inverters. Deployed thousands of times — the technology’s proof of market.

All integration routes are compatible with the 15-minute intervals of common smart meters and their cloud services.

Already in series production: the Maxxicharge CCU V2 all-in-one plug-in storage system by Maxxisun is on the market with ready2plugin inside.4

The bridge to the product standard

Stay on the market until your engineers can certify again.

These two to three years are not a waiting period — they are when your market position is decided. The market for plug-in storage is currently growing around three and a half times faster than fixed installations. Whoever can offer safe, high-performance feed-in during this phase will take the boom market. Whoever waits for the product standard leaves it to others. Whoever ships devices without this protection carries the compliance and liability risk alone.

As long as no closed product standard for plug-in storage exists — expected to be another two to three years — a ready2plugin licence is the way to establish the required cable overload protection and to ensure the safety of socket feed-in. You take on the tested building block for precisely the safety analysis that would otherwise rest entirely with you. Once the standard is published, your engineers can certify against it again — in the meantime, ready2plugin keeps your products capable and marketable.

For the cost of a customary dealer margin — a surcharge of around 5 % on the device price — you get a high-performance, independently tested socket feed-in while avoiding the expensive risks of a gap in cable protection.

A gap in cable overload protection is not only a technical issue. It carries commercial and legal risk that does not stop with you, but reaches your entire distribution channel:

  • injunctions and sales bans in the case of non-compliant devices
  • rework and recall of devices already delivered
  • strict product liability under the German Product Liability Act (ProdHaftG)
  • distributor liability under warranty law (§§ 437, 634 BGB) and for misleading commercial practices (§ 5 UWG)
  • damages for patent infringement in the case of in-house development
Advice at first hand

Advised by the specialist who negotiated socket feed-in into the VDE standards in the first place.

Marcus Vietzke has coordinated the DGS working group PVplug since 2016, is co-author of the product standard DIN VDE V 0126-95 and contributes to DKE committee 373. Over roughly ten years of standardisation work he negotiated the socket connection of solar systems into the VDE standards — from the installation standard through layperson registration to the product standard. That experience is at your side during integration. We negotiated plug-in solar into the standards; with ready2plugin at your side we will bring your plug-in storage systems into the regulated market as well.

A proven building block

A tested solution while the product standard takes shape.

The product standard for plug-in storage is still being developed. ready2plugin already provides the cable overload protection that today’s applicable VDE standards require, as an independently tested solution.

Licensing it means you do not have to build and validate your own protection under time pressure. You adopt a tested building block and keep your focus on your product.

Talk to us about licensing.

We support the implementation — from firmware integration to the cloud API.

Two reasons to license ready2plugin: it unlocks maximum usable energy for your customers, and it is independently tested by the Fraunhofer ISE.

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Notes

  1. 1,075 kWh corresponds to the annual yield of 960 Wp of module capacity at a German location on a multi-year average. 22,770 kWh is the usable feed-in corridor with dynamic cable overload protection. Self-consumption rates of up to 80 % are achievable in households with an annual demand of up to 7,000 kWh.
  2. Function and fail-safe behaviour were assessed by the Fraunhofer Institute for Solar Energy Systems ISE within the DKE standardisation project (funded by the German Federal Ministry for Economic Affairs and Energy). The report states, in the original German: „praxisnah erfolgreich getestet“ (final report, page 35). The more than 300 measurements from real installations are indielux GmbH’s own development work and are to be distinguished from the Fraunhofer ISE assessment.
  3. Patents granted in Germany, France, the United Kingdom, Switzerland, the United States, Brazil, China and India. Protection until at least 2038.
  4. The Maxxicharge CCU V2 by Maxxisun (Maxxihandel GmbH), with integrated ready2plugin technology, is available on the market.
  5. This page provides general information on the applicable standards for plug-in solar devices and does not constitute legal advice. The assessment of individual products or configurations remains subject to case-by-case review.