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">Partnerships for enhanced engagement in research (PEER) SCIENCE
Cycle 3 (2014 Deadline)

PRESSA: Photovoltaic Reliability Evaluation in Sub-Sahara Africa

PI: Gabriel Takyi (, Kwame Nkrumah University of Science & Technology
U.S. Partner: Christiana Honsberg and Mani G. TamizMani, Arizona State University (ASU)
Project Dates: September 2014 to February 2019

Many countries are procuring and installing large numbers of photovoltaic (PV) modules for various grid-tied and stand-alone applications. These modules need to be evaluated to ensure that they will meet the safety requirements (both electrical and mechanical), meet the nameplate rating requirements (rating tolerance shall be minimum), and be reliable and durable for at least 20 years. Because consumers decide to purchase modules based on their "$/watt" ratio as per the nameplate rating, it is critical to ensure that the rating is accurate. In this PEER project, the nameplate rating will be verified by the principal investigator's laboratory in Ghana before procurement decisions are made by investors and the government of Ghana.

The lifetime of PV modules is dictated by failure modes and degradation rates. PV module manufacturers typically provide 20-year warranties, but there are two problems. First, due to the dynamic nature of the investors’ decisions, many manufacturing companies do not last longer than a few years, rendering the 20-year warranty useless. Second, most manufacturers provide a 20-year warranty due to heavy competition in the industry but do not have substantiated evidence to justify these long warranty periods. Based on the experience gained in the U.S. partners' laboratory at ASU, it has been demonstrated that the majority of modules do not meet warranty requirements, and most manufacturers are no longer in business to make good on warranty claims when they are made. Three of the major failure/degradation modes in the climatic conditions prevalent in Ghana are solder-joint degradations/failure; encapsulate browning; and high relative humidity/rain-related degradation. In this PEER project, samples of PV modules will be evaluated for the above failure and degradation modes both in the field and the laboratory.

Two major impacts are expected with regard to purchasing decisions by various stakeholders, including the government of Ghana and Ghanaian investors and consumers. The first impact is related to nameplate rating verification. The stakeholders can purchase the modules based on their independently measured power provided by the Ghanaian researchers rather than their manufacturer rated power. The second impact is related to the lifetime of the modules in the field. An extensive evaluation of PV modules is required to predict module lifetime under various climate conditions. In the proposed limited-budget PEER project, the entire lifetime-related research cannot be performed, but a few key reliability studies will be carried out in the laboratory and in the field to identify the major failure modes using less expensive, non-destructive tests.

Summary of Recent Activities

This project has come to an end. The PI reports that the data collected so far under PRESSA provides compelling evidence that some of the PV modules that are imported into this Ghana do not perform as expected based on the manufacturers’ nameplate ratings. The Ghanaian consumer (including individuals, Government Agencies etc.) and other stakeholders must be aware of this through the demonstration of their research findings. The results of one of the research work packages on risk priority number (RPN) on a 2.5 MW Solar Power Plant in Northern Ghana indicates that after only 5 years of operation the rate of degradation has exceeded the rate that is expected in 25 years. This shows that the panels were not of high quality. These results will be presented to the Volta River authority, the operators of the plant. They have been able to show the performance in terms of prevalent degradation and rate of degradation of different PV modules technologies installed at different climatic zones (Tropical Savannah and Semi-Arid Zones) in Ghana.

The project's potential development impacts include:

1. Prediction of life of PV Modules installed in SSA using accumulated strain energy density from the modelling of solar PV interconnections.
2. The prevalent defect of PV Modules installed in the Tropical Savanna and Semi Arid climatic Zones in Ghana have been identified. This could be of great benefit in product development.
3. The use of climatic condition (temperatures of KNUST) has helped us to generate a temperature profile representative of sub-Sahara Africa. This Information will be useful for manufacturers in the design of robust crystalline silicon PV modules. 

As the project ends, one PhD student is putting his thesis together for final submission. Two Postgraduates (one MSc graduated in February 2019), one MPil student also successfully had his final oral presentation on 26th March 2019 and will graduate in June 2019. Their topics are as follows:

1. MPhil: Assessment of Risk Priority Number of 2.5 MW Solar Power Plant at Navrongo, Ghana in Sub- Saharan Africa
2. MSc: Field Study on the Prevalent Degradation Forms for Photovoltaic Modules Operating Under Various Climatic Conditions in Ghana.

Two groups of BSc students also graduated in July 2018. Their project topics were:

1. Performance evaluation of 11-year old PV modules installed at KNUST
2. The effect of angle of inclination on the power output of solar panels installed at KNUST

The PI and his team will continue to collaborate with the US Partner on both current and new research. KNUST is currently partnering ASU on MasterCard Accelerated Masters Degree Programs (3+1+1) in Mechanical
Engineering, Biomedical Engineering and Business Programs. Under this program, ASU will be training upto150 KNUST students for 5 years. The US partner has agreed to take some of the students to do their projects in his laboratory at ASU Polytechnic

PEER Cycle 3 Grant Recipients