Sini Numminen, M.Sc.(Tech.)

I am a PhD student at the School of Science at Aalto University, Finland. In 2009 I graduated from Helsinki University of Technology in Electrical Engineering with a minor in Development Studies at the Department of Social Sciences in Helsinki University. After graduation I worked in Germany as a researcher in a European association Distributed Energy Resources Laboratories (DERlab) where I gained a strong insight on the potential of renewable and distributed power units and the smart grids concept. My PhD work is supported by a research grant from the Tiina and Antti Herlin Foundation, Finland.

Personal Data

Nationality: Finnish
Country: Finland
Research Group: New Energy Technologies Group in the School of Science at Aalto University
PhD supervisor: Professor Peter D. Lund
PhD Grant: 2016 - 2019 from Tiina ja Antti Herlin Foundation
Master’s Degree (major): Electrical Engineering at Helsinki University of Technology
Master’s Degree (minor): Development Studies at the Department of Social Sciences at Helsinki University
Email: sini.numminen[a ]
Website: LinkedIn


  • Evaluation of the reliability of solar micro-grids in emerging markets – Issues and solutions - Numminen, S., Lund, PD. (2019). Energy for Sustainable Development, vol 48, pages 34-42. doi:10.1016/j.esd.2018.10.006. Abstract: One of the most important technical features of a power system is its ability to deliver electricity reliably to the customers. Based on interviews with 12 energy service companies (ESCO) currently operating solar micro-grids in northern rural India, this study identified important factors related to technical design, customer behaviour and operations and management (O&M) that may result in contingencies in service. In addition, the study presents companies’ innovative solutions to overcome these problems. Initially, the interview method allowed only a rough qualitative comparison of different reliability levels as the availability of comparable data was limited. We found that a more descriptive method for reliability assessment would create equally valuable information on renewable off-grid energy projects. We propose a simple framework for assessing reliability that highlights the particular features of off-grid areas in developing countries.

  • Power availability and reliability of solar pico-grids in rural areas: a case study from northern India - Numminen, S., Lund, PD., Yoon, S., Urpelainen, J. (2018). Sustainable Energy Technologies and Assessments, vol 29, pages 147-154. doi:10.1016/j.seta.2018.08.005. Abstract: Solar micro-grids are receiving increasing interest in the electrification in emerging economies. On-site performance studies of these systems have become more important as the global market is being supplied with an ever-greater variety of solar power equipment with inconsistent quality. We studied the reliability of seven small identical low-power DC solar grids installed in real settings in villages in rural northern India. A detailed analysis of measurement data, interviews and field visits over a whole year showed that solar electricity was available to the households for 87% of the time. Along with technical problems, a share of the power shortages was an indirect cause of an illegal behaviour of users. The study draws attention to quality recommendations for energy access for consumers with modest energy needs.

  • An Evaluation of Dynamic Electricity Pricing for Solar Micro-Grids in Rural India - Numminen, S., Yoon, S., Urpelainen, J., Lund, P.D. (2018). Energy Strategy Reviews vol 21, pages 130-136. doi:10.1016/j.esr.2018.05.007. Abstract: Stand-alone photovoltaic systems provide a potentially sustainable option for rural electrification, but the design and management of these systems is a challenge. Here we examine the ability of dynamic (real-time) pricing in off-grid systems to improve the durability of the batteries used to store power. In a randomized controlled trial with a pre-paid solar micro-grid in rural India, we found that dynamic pricing did not improve technical performance or customer satisfaction. The best explanation for the null finding is that, for various reasons, households minimized their power consumption and there was thus little need for demand management. These findings suggest that the low demand for power is a key challenge for the profitability of pre-paid off-grid systems.

  • Frugal energy innovations for developing countries – a framework - Numminen, S., Lund, P.D. (2016). Global Challenges. John Wiley & Sons. doi:10.1002/gch2.1012. Abstract (extract): Frugal innovations have recently emerged to feature low-cost technologies and business innovations to serve consumers in emerging markets and improve their quality of life. Although the concept of frugality is well known, the present literature on frugal energy innovations, or energy frugality, is scarce, which could lead to overlooking its true characteristics. Therefore, we propose a framework for defining energy frugality based on a detailed analysis of several low-cost sustainable energy technologies. - - -

  • Implications of frugal innovations on sustainable development: evaluating water and energy innovations - Levänen, J., Hossain, M., Lyytinen, T., Hyvärinen, A., Numminen, S., Halme, M. (2016). Sustainability 2016, 8(1), 4; doi:10.3390/su8010004. Abstract (extract): Frugal innovations are often associated with sustainable development. These connections, however, are based on anecdotal assumptions rather than empirical evidence. This article evaluates sustainability of four frugal innovations from water and energy sectors. For the purposes of the evaluation a set of indicators was developed. Indicators are drawn from sustainable development goals by the United Nations and they encompass central dimensions of sustainability: ecological, social and economic. - - -


  • Finnish - Mother tongue
  • English - Fluent
  • Swedish - Good
  • French - Good
  • German - Basic