May 18, 2023

Audio: Data-Driven Design of Off-Grid Solar Home Systems

Experts in solar energy system design guide us through a case study of off-grid systems in communities in the Navajo Nation, the Native American reservation in the mountains and deserts of the American West. The study examines the characteristics of electricity consumption in 150 off-grid Navajo Nation solar homes, focusing on daily energy usage and its implications for off-grid system design.

This presentation took place in a webinar in April 2023, led by Dr. Henry Louis, professor of electrical and computer engineering at Seattle University, Derrick Terry, a Renewable Energy Specialist for Navajo Tribal Utility Authority, and Mohammed Ba-Aoum, a former Senior Fellow at Engineering for Change and a Ph.D. candidate in Industrial and Systems Engineering at Virginia Tech.

We now present an audio transcript of the webinar with slides. Find a time-annotated summary below the embedded audio-text file.

Discover more expert presentations in our Off-Grid Energy Webinar Series

Data-Driven Design for Off-Grid Systems: Electricity in the Navajo Nation


  • Introduction to today’s webinar. 0:02
    • Welcome to the webinar.
    • About engineering for change and its mission.
  • Intro to the webinar. 2:28
    • Get familiar with the critical functions, including chat.
    • Welcome to the webinar.
    • Introduction of the guests and the topic.
    • Introductions of the guest speakers.
  • What Is energy poverty? 7:12
    • Access to electricity is a form of energy poverty.
    • 70% of the people without access to electricity live in
    • Rural electrification in the United States and off-grid electrification on the navajo nation.
    • The challenges and opportunities.
  • Derek’s introduction. 12:39
    • Renewable energy specialists for the navajo nation.
    • 31% of homes lack complete plumbing and water.
    • The navajo nation and the hopi reservation.
    • The importance of renewable energy.
  • How much does it cost to run a solar home? 17:17
    • Average household income is above $8,000, not per month.
    • Energy efficiency and sustainability.
    • The challenges of traveling on navajo.
    • The main importance of solar is light.
    • Three days of autonomy for the system.
    • The importance of family reliable electricity.
  • The off-grid systems themselves. 23:53
    • The off-grid systems themselves.
    • Data going to the homes exceeds the power going to homes.
    • Diversity in energy consumption in the navajo nation.
    • Energy consumption over the two-year period.
  • How much energy are homes consuming? 30:15
    • Energy consumption on the ac side of the system.
    • Energy on the dc side.
  • Daily energy consumption for homes. 33:29
    • Homes consumed a wide variety of energy.
    • Load profiles of 25 homes.
    • Consistency of load from one season to the next.
    • Design of the arrays.
  • Battery bank sizing and autonomy. 39:34
    • Battery bank size and days of autonomy.
    • Service costs and maintenance costs.
    • Analyzing battery voltage profiles for reliability of the system.
    • Time series analysis for battery.
  • What’s next for this work? 46:11
    • Average daily consumption of electricity in sub-Saharan Africa.
    • Next steps for the study.
    • Contact informations and Q and a.
    • Who finances the MTU and revenue model.
    • Designing standalone systems for some households.
    • Understanding distribution of energy consumption.
  • Batteries and maintenance. 52:26
    • The lifespan of the batteries, especially maintenance-free batteries.
    • Maintenance-free battery agm.
    • Two questions from the audience.
    • Tools and resources for designing systems without historical data.
  • Load estimation and load estimation tools. 58:15
    • Webinar series for engineering for change, load estimation.
    • Data flows before the monitoring system.
    • 50 fields of data for each unit of data.
    • 20 more questions left unanswered.

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