SONNWINN
Drone image of a ground-mounted PV plant with battery storage containers, transformer stations and inverters between the module rows

Technical inspection of PV plants and battery storage

Independent experts for photovoltaics and battery energy storage systems (BESS) in Germany: acceptance, measurement, due diligence and warranty – from construction to operation.

Photo: DroneWize

Services at a glance

Acceptance and commissioning inspection

Inspection of the PV plant and storage system before acceptance or commissioning, based on DIN EN IEC 62446‑1 (VDE 0126‑23‑1) and DIN EN IEC 62933‑2‑1.

Technical due diligence

Technical project review when a plant or a portfolio is acquired.

Inspection by measurement

String measurement, thermography and aerial images, insulation resistance, testing according to DIN EN IEC 62446‑1 (VDE 0126‑23‑1).

Construction progress monitoring

Inspection of construction progress to identify defects and deviations from the contract early.

End-of-warranty inspection

Making hidden defects visible while remedial work can still be demanded.

Technical asset management

Regular, independent inspection and evaluation during operation.

Acceptance and commissioning inspection

A thorough inspection is essential so that no defects or faults are overlooked at acceptance or commissioning. We inspect the PV plant and, where present, the battery storage system.

Scope of inspection, PV plant

based on DIN EN IEC 62446‑1 (VDE 0126‑23‑1)

  • visual inspection of the installation
  • safety review of the plant
  • inspection of the mounting structure
  • measurement of the string currents
  • thermography
  • drone survey
  • comparison with the design documents
  • review of the commissioning documentation
  • check of the function of the plant monitoring
  • further inspection items by agreement

Scope of inspection, battery storage (BESS)

based on DIN EN IEC 62933‑2‑1

  • documentation and commissioning records
  • system status of the BESS
  • effectiveness of protective devices and switchgear
  • execution of the test cases developed with the client
  • evaluation of the BMS logs

For storage systems we have been trained by several manufacturers, e.g. Commeo, ABB, Tesvolt, Varta and Kostal.

Inspectors in high-visibility vests in front of an open inverter and medium-voltage station on a construction site
Acceptance inspection of a station
String inverter on the mounting structure of a ground-mounted PV plant, module rows behind
Inverter in the module field
Open battery cabinet of a storage system with stacked battery modules and power connections
Battery cabinet of a storage system
Folding rule between the lower edge of a module and the ground to measure the ground clearance
Measuring the ground clearance

Technical due diligence (technical project review)

If a PV plant or an entire portfolio is to be acquired, we review the technical aspects down to the plant documentation. We identify defects and assess the technical risks.

Aerial image of a ground-mounted photovoltaic plant with a substation, a motorway alongside
Ground-mounted plant with substation, drone image

Inspection by measurement

Measurements reveal defects and faults.

  • string measurement
  • thermography and aerial images
  • insulation resistance measurement
  • testing according to DIN EN IEC 62446‑1 (VDE 0126‑23‑1)
Drone in front of a PV module field during a survey flight
Drone survey of a module field
Thermal image from a drone: one module with a clearly warmer spot (hotspot)
Thermography: hotspot on a module
Drone image of a damaged module: broken glass with a foreign object on the module surface
Drone photo: broken glass
Measuring the string current with a clamp meter on a cable below the mounting structure
Measuring the string current
Thermal image of the string connections below an inverter with temperature readings
Thermography of the string connections

Construction progress monitoring

During construction we inspect the progress of the works. Defects and deviations from the contract are thus identified early, and countermeasures can be taken.

Construction site of a ground-mounted PV plant: installed mounting structure without modules, open cable trench and excavated soil
Mounting structure and cable trench during construction
Digital inclinometer on a module showing 9.60 degrees
Checking the module tilt
Thermal image from a drone over several module rows with an even temperature distribution
Thermography from the drone over several module rows

End-of-warranty inspection

Until the warranty period ends, hidden defects can be reported and remedial work can be demanded. We make hidden defects visible and advise you on the possible steps.

Close-up of a module clamp at the edge of a PV module on a trapezoidal sheet metal roof
Module fixing on a trapezoidal sheet metal roof
Close-up of a module clamp with screw on the module frame
Module clamp on the frame
DC connector on a module in the hand of an inspector
Checking the connectors
Thermal image of a rooftop plant from a drone, individual modules stand out in colour
Thermography of a rooftop plant

Technical asset management (TAM)

For an unbiased condition report, it is advisable to have plants inspected from time to time by an independent party.

  • regular and on-request inspections
  • assessment of defects and their rectification by the O&M operator
  • monitoring and evaluation of the plant yields
  • preparation of reports
  • advice on measures to increase yield
Aerial image of an industrial building roof with several module fields between skylights
Rooftop plant on an industrial building, drone image
Inverter on a wall with connected string cables
Inverter with string connections

Frequently asked questions

What does the acceptance inspection of a PV plant cover?

The inspection is based on DIN EN IEC 62446‑1 (VDE 0126‑23-1): visual inspection of the installation, safety review, inspection of the mounting structure, measurement of the string currents, thermography and drone survey, comparison with the design documents, review of the commissioning documentation and of the function of the plant monitoring. Further inspection items are added by agreement.

Do you also inspect battery storage systems?

Yes. We inspect battery energy storage systems (BESS) based on DIN EN IEC 62933‑2-1: documentation and commissioning records, system status, effectiveness of protective devices and switchgear, test cases developed with the client and evaluation of the BMS logs. For storage systems we have been trained by several manufacturers, e.g. Commeo, ABB, Tesvolt, Varta and Kostal.

Which measurements do you carry out on existing plants?

String measurements, thermography and aerial images, insulation resistance measurements and tests according to DIN EN IEC 62446‑1 (VDE 0126‑23-1). These reveal defects and faults.

Why inspect before the end of the warranty period?

Until the warranty period ends, hidden defects can be reported and remedial work can be demanded. We make hidden defects visible and advise on the possible steps.

What is checked in a technical due diligence?

When a PV plant or a portfolio is acquired, we review the technical aspects down to the plant documentation, identify defects and assess the technical risks.

What does technical asset management provide?

An independent party inspects the plant regularly or on request, assesses defects and their rectification by the O&M operator, monitors and evaluates the yields and prepares reports. This gives an unbiased picture of the condition of the plant.

How long does a technical inspection take?

Usually two to three weeks after the order is placed. If it is urgent, please contact us.

Enquiry

Use the form, call us on +49 4103 121 4221 or write to kontakt@sonnwinn.de – whichever suits you best.

You do not need to attach documents to your enquiry – once we have received it, we will help you put together the documents required.

Which documents are helpful
  • Type and size of the plant, location and preferred inspection date
  • Design documents of the plant as built
  • Commissioning documentation, for storage systems also commissioning records
  • If available: access to the plant monitoring
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