Robust fixed effects regression coefficients for project impact on food security indicators. Column 1 shows the difference in outcome variables across all villages and households between November 2008 and 2007 (the overall time trend). Column 2 shows the effect difference for households in treatment villages versus households in control villages over time (the simple effect of living in a project village); column 3 shows effect difference for households with a member in a women’s agricultural group versus non-group-member households across both treatment and control villages over time (the simple effect of being in a women’s agricultural group). Finally, column 4 gives the difference-in-difference coefficient for project impact—the difference in each outcome variable between women’s group member households in treatment villages and the rest of the sample—over the first year of the project. All consumption and purchase data account are given in per capita daily USD at purchasing power parity (PPP), accounting for inflation and allowing for comparison between metrics. Red and blue values are average values for the entire year; green and yellow markers show breakdown for rainy and dry seasons, respectively. [Error bars indicate 95% confidence range; significance: ^p < 0.1 *p < 0.05 **p < 0.01 ***p < .001]

(A) Cartoon schematic of a PVDI system. A PV array powers a water pump, which fills a large concrete reservoir; water is then gravity-distributed at a pressure of 1–3.5 m head through drip irrigation lines. (B) Passive regulation of PVDI systems shown for January 2008–January 2009. Maximum evapotranspiration (ET) need calculated from local weather data (assuming clear sky and no rainfall) is plotted in black. Any shortfalls for expected pump output for average annual weather patterns (Red) and actual pump output (Blue) are met by actual precipitation (Green).

NPV of comparable solar- and liquid-fuel-powered drip irrigation systems across discount rates for a range of photovoltaic system and fuel costs (n = 15 yr).