Solar sales in Kenya are among the highest per capita among developing countries. While this commercial success makes the Kenya market a global leader, product quality problems have been a persistent concern. In this paper, we report performance test results from 2004 to 2005 for five brands of amorphous silicon (a-Si) photovoltaic (PV) modules sold in the Kenya market. Three of the five brands performed well, but two performed well below their advertised levels. These results support previous work indicating that high-quality aSi PV modules are a good economic value. The presence of the low performing brands, however, confirms a need for market institutions that ensure the quality of all products sold in the market. Prior work from 1999 indicated a similar quality pattern among brands. This confirms the persistent nature of the problem, and the need for vigilant, long-term approaches to quality assurance for solar markets in Kenya and elsewhere. Following the release of our 2004/2005 test results in Kenya, the Kenya Bureau of Standards moved to implement and enforce performance standards for both amorphous and crystalline silicon PV modules. This appears to represent a positive step towards the institutionalization of quality assurance for products in the Kenya solar market. (c) 2006 Elsevier Ltd. All rights reserved.