DERpass · Use Cases

Life-cycle events
that need good data.

Every PV system will be inherited, sold, repowered, handed over, or taken on by a new operator. Each of these moments fails without a complete, portable asset record. DERpass makes them work.

End-to-End Walkthrough Inheritance System Sale Repowering Commissioning Handover Maintenance Takeover
End-to-End 10 kWp Residential

One file, the full life of the asset.

A single .derpass follows a 10 kWp rooftop system from commissioning day through the first maintenance visit to a property sale two years later. Every party — installer, O&M provider, insurer — works from the same file without re-keying a single field.

Installers O&M Providers Insurers Lawyers & Notaries
Day 1
Installer
Draft passport generated from commissioning report

The installer uses the AI prompt to convert the commissioning report PDF into a draft DER Passport. Hardware specs, inverter serial numbers, MaStR number, and feed-in tariff rate are extracted and mapped to the correct schema fields. The process takes about 30 seconds.

Use the AI prompt →
Day 1
Installer
Validated in the viewer

The installer drops the file into the DERpass Viewer. Every chapter renders: components match the datasheet, grid connection shows the correct DSO, the feed-in tariff matches the contract. The file is saved as musterstrasse-12.derpass.

Open Viewer →
Day 1
Installer → Homeowner
Single file handed over

The installer attaches the .derpass to the handover email. The homeowner receives one structured file instead of a folder of scanned PDFs, datasheet printouts, and grid approval letters. The file travels with the property from this point forward.

+6 months
O&M Provider
Maintenance event appended

The O&M provider receives the same file from the owner. After the first scheduled service visit, they append an event to the events array — date, technician name, work performed. The content-hash chain records the revision, making any subsequent tampering detectable. The updated file goes back to the owner.

+2 years
Buyer's insurer
Due diligence completed in minutes

The homeowner sells the property. The buyer's insurer validates the file against the JSON Schema — component ages, maintenance cadence, and existing insurance coverage are all machine-readable. There is no questionnaire. No phone calls chasing missing certificates. The underwriting assessment takes minutes, not weeks.

View the schema →
Try it yourself
Generate with AI 10 kWp Example Open in Viewer
Life event Estate & Succession #inheritance

Inheritance

A homeowner with a 12 kWp PV system dies. Their heirs have no technical background — they do not know who installed the system, whether it is insured, what feed-in tariff contract exists, or when the next maintenance is due. Without a structured record, every answer requires a separate investigation.

Lawyers & Notaries Installers O&M Providers Insurers
Without DERpass
1

Heirs search filing cabinets and email for an installer invoice. The installer may have changed name or gone out of business.

2

The DSO is contacted to identify the grid connection. The process to retrieve account details from a deceased person's estate can take weeks.

3

Insurance policy is found in a paper folder — or not found at all. Coverage lapse risk is high during the estate settlement period.

4

An O&M provider is asked to take over maintenance but has no record of what is installed, requiring a paid site survey before they can begin.

With DERpass
1

The .derpass, stored with the property documents, contains the installer name, contact, and certification number. One file, found once.

2

The grid connection chapter contains the GCP ID, EAN/MaStR number, and DSO contact. The compensation chapter shows the FiT rate and contract expiry.

3

The insurance chapter lists the active policy, insurer, and expiry — visible immediately. The heirs notify the insurer with accurate data the same day.

4

The O&M provider receives the .derpass. They validate it, see the full component list and event history, and can begin scheduled maintenance without a site survey.

Related example
10 kWp Home System Legal Player
Transaction Property & Asset Sale #system-sale

Sell the System

A homeowner sells their house. The buyer wants to know: what PV system is installed, does the feed-in tariff contract transfer with the property, are there open warranty claims, and what is the historical yield? Without structured data, the seller cannot answer these questions, and the buyer cannot verify the answers they receive.

Lawyers & Notaries Investors Installers Grid Operators
Without DERpass
1

Seller requests commissioning documents from the installer — often no longer available five to ten years later. Buyer has no independent way to verify specifications.

2

FiT contract transferability must be confirmed with the grid operator. The process requires submitting forms and waiting for written confirmation — adding weeks to the transaction.

3

Yield data lives in a monitoring platform account owned by the seller. There is no standard format to export and hand it over. The buyer cannot independently verify performance claims.

4

The buyer's solicitor cannot establish an independent chain of title for the PV system component of the property — it is treated as an unverifiable fixture.

With DERpass
1

The seller hands over the .derpass with the property deed. The buyer validates it against the schema — components, commissioning date, and installer certification are immediately verifiable.

2

The compensation chapter shows the FiT rate, contract reference, and expiry date. The grid connection chapter contains the GCP ID and MaStR number for the transfer notification.

3

The generation data chapter carries annual yield, monthly breakdown, and performance ratio — structured, queryable, and independent of the monitoring platform account.

4

The revision history shows the complete ownership chain with dates and document references. The new ownership event is appended to the file at transaction close — the record is continuous.

Related example
10 kWp Home System Legal Player Open in Viewer
Life cycle Component Replacement #repowering

Repowering

An 18-year-old system needs new inverters. A technician visits, replaces them, and adds a battery. Without a structured record, the component history breaks: the original inverter data is gone, the new equipment is undocumented, and the next party to interact with the system — an insurer, investor, or new owner — inherits a gap.

Installers O&M Providers Investors Insurers
Without DERpass
1

The technician arrives on site. There is no commissioning record from 18 years ago. They photograph the existing inverter nameplate on their phone.

2

The old inverter is removed. The photo on the technician's phone is the only record of the original component — serial number, model, and installation date are lost.

3

The new inverter and battery are installed. The installer issues a new commissioning report as a PDF. It does not reference the previous system state.

4

An investor or insurer reviewing the system sees a commissioning date of this year — and a gap where the previous 18 years of history should be. The full asset value cannot be assessed.

With DERpass
1

The existing .derpass is opened on the technician's device. The original commissioning data — inverter model, serial, installation date — is visible and available.

2

A component_removal event is appended to the event log: original inverter serial, date of removal, reason (end of life), and technician. The history is complete.

3

The inverters and battery chapters are updated with the new component data. A component_addition event is appended for the battery. The file carries the full before/after picture.

4

The revision history records the repowering as a named file version. Any subsequent party — insurer, investor, buyer — sees the complete asset history from original commissioning to present.

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Workflow EPC to O&M #commissioning-handover

Passing Documentation After Commissioning

An EPC contractor finishes installing a 250 kWp commercial plant. The asset is acquired by an infrastructure fund. O&M goes to a third-party operator. Three parties need the same data — in formats their systems can actually consume. Today, this results in three diverging records within months.

Installers O&M Providers Investors Grid Operators
Without DERpass
1

EPC sends a ZIP archive to the asset owner: commissioning report PDF, datasheet scans, inverter config exports, and a grid approval letter in different formats.

2

The fund's asset manager extracts key data into their own Excel template. The O&M provider builds their own spreadsheet from the same ZIP. Both records diverge from day one.

3

Six months later, the fund and O&M provider have different DC capacities recorded, different inverter serial numbers, and different commissioning dates — all from the same original ZIP.

4

When the DSO requests updated metering data, each party provides a different answer. Resolving the discrepancy requires a site visit and weeks of reconciliation.

With DERpass
1

A single .derpass is created at commissioning sign-off — all components, metering concept, grid connection, and the installer's JWS-signed commissioning event included.

2

All three parties — fund, O&M provider, DSO — receive the same file. Each validates it against the schema and imports it into their platform. One source, three consumers.

3

The O&M provider appends events to the file from their own system. The fund and O&M provider always have the same canonical component data — it cannot diverge because there is only one file.

4

When the DSO requests updated metering data, the O&M provider exports the metering chapter of the current .derpass. There is one version of the truth, and it is always current.

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Operations Undocumented Fleet #maintenance-takeover

Offer Maintenance for Existing Projects

An O&M provider is asked to take over maintenance of 30 residential systems commissioned five to eight years ago. There is no structured documentation — just folders of PDFs from several different installers. Before any productive work can begin, the operator must reconstruct the asset register from scratch.

O&M Providers Installers Insurers
Without DERpass
1

The O&M provider requests documentation from each of three different original installers. Two respond with PDFs; one does not respond at all.

2

A technician visits every system to photograph nameplates and read meter IDs. Ten systems have been partially repowered — the components no longer match the original PDF. Both versions go into the register.

3

After four weeks, the O&M provider has a partially complete asset register in their own spreadsheet format. Yield history is missing — it lives in the original owners' monitoring accounts.

4

The first maintenance visit is scheduled. The technician arrives and finds a different inverter model than the register shows — the photograph was of the wrong unit. The register is updated manually, again.

With DERpass
1

The O&M provider creates a baseline .derpass for each system by visiting and reading the current nameplate data. Partial data is valid against the schema — the file can be completed over time.

2

For the ten systems with existing documentation, any PDF data is entered into the structured file. The event log records "baseline documentation created" as the first event — the history starts here.

3

From this point forward, every maintenance visit is logged in the event chapter. The asset register and maintenance history are the same file — there is no divergence between systems.

4

After two years, each system has a complete event log from takeover date. When an owner asks for a portfolio report, it is generated from 30 structured files — not assembled from 30 spreadsheets.

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