Accurately Assess the Integrity of Solar Power Systems

Nagano, Japan

Hioki E.E. Corporation is pleased to announce the launch of the PV Power Verifier LR8400-92 and LR8400-93.

*PV refers to “photovoltaic,” a type of solar power system.

Currently, the creation of feed-in tariff mechanisms worldwide is fueling growth in the installed base of photovoltaic solar power systems, and with it demand for products aiding in the maintenance and management of connected equipment. Hioki developed the LR8400-92 and LR8400-93 founded on the anticipated growth in demand for measuring instruments capable of assessing and verifying the amount of electricity generated by photovoltaic systems such as solar cells.

In addition to estimating optimal electricity generation for photovoltaic solar power systems, the PV Power Verifiers measure actual generation. By comparing expected power with actual power, energy auditors and maintenance technicians can assess whether solar power generating systems are operating properly. If an equipment failure is suspected, the instruments can also be used to pinpoint its location. Hioki test and measurement products simplify maintenance and management compared to what is possible with older instruments, dramatically increasing the level of convenience for customers.

The PV Power Verifier LR8400-92 includes a 200 A AC/DC clamp on current sensor, while the LR8400-93 includes a 2000A AC/DC clamp on current sensor.

Development Background
Globally, local authorities are implementing feed-in tariff mechanisms for renewable energy, which often require power companies to enter into electricity supply contracts with stipulated purchase prices and timeframes when so requested by renewable energy producers. Since companies and other entities that see the feed-in tariff mechanism as a business opportunity to enter into the renewable energy business, numerous new photovoltaic installations are being built.

Hioki developed the PV Power Verifiers LR8400-92 and LR8400-93 based on its projection of growing demand for measuring instruments capable of assessing whether photovoltaic solar power systems are producing the proper amount of electricity. Growth in the installed base of such systems is expected to bolster the need for maintenance and management products.

Product Architecture
The LR8400-92 and LR8400-93 use channels 1 and 2 to measure actual electricity generation and channels 3 and 4 to estimate optimal generation based on the following architecture:
Channel 1: Differential probe, used to measure voltage
Channel 2: Clamp sensor, used to measure current
Channel 3: Pyranometer, used to measure solar irradiance
Channel 4: Thermocouple, used to measure solar panel temperature

Hioki is in the process of patenting this approach to measuring photovoltaic solar power system performance, which is the first of its kind in the industry.


1. Easy assessment of whether photovoltaic systems are generating the proper amount of electricity

The PV Power Verifier estimates the amount of electricity that the photovoltaic system should be able to generate based on solar irradiance as measured with a pyranometer and the temperature of the solar panel. It then measures the amount of electricity actually being generated at the system’s junction box*. By comparing estimated and actual electric energy data, the energy auditor or technician can assess whether the solar power generation system is performing properly.

Under the conventional approach to maintain and manage photovoltaic systems, which relies on a measuring instrument known as an I-V curve tracer, the solar power generation system has to be shut down for testing. Hioki instruments can be used to measure system performance while it is online, making the maintenance process significantly more convenient and efficient.

The Hioki PV Power Verifiers also differ from the conventional approach of checking generation status by examining I-V curves in that in they rely on a comparison of estimated and actual electric energy that requires no specialized knowledge on the part of operators.

*Junction box: Equipment that brings together multiple wires from solar panels and connects them to a power conditioner.

2. Identification of failed solar strings
Photovoltaic systems group together solar panels in series into units known as strings in order to produce the desired level of electric energy. Consequently, when a system is affected by a failure or other problem, it is necessary to identify the string in which the issue has occurred. The LR8400-92 and LR8400-93 be used to identify the location of problematic strings by measuring the voltage and current at individual wires inside the system’s junction box.

The Hioki PV Power Verifiers can assist the following customers:

* Maintenance departments at photovoltaic system manufacturers
* Electrical equipment maintenance companies       
* Photovoltaic system operators, etc.

Established in 1935, HIOKI E.E. CORPORATION (TSE: 6866) has grown to become a world leader in providing consistent delivery of test and measuring instruments through advanced design, manufacturing, and sales and services. By offering over 200 main products characterized by safety and quality while meeting an expansive range of applications, we aim to contribute to the efficiency and value of our customers’ work in research and development, production and electrical maintenance. HIOKI products and services are available around the world through our extensive network of subsidiaries and distributors. Information about HIOKI is available at