lighting or grid connection. In addition, the study site was also home to a substantial ultra-poor population that could be the main target of solar products. Third, in this study, we randomized the intensity of solar lighting by varying the product amount. Providing multiple solar lanterns reduces the likelihood that other family members exclusively utilize the products and therefore, discourage children’s nighttime use for study.

As the empirical analysis will demonstrate, the treated children who received solar lanterns achieved no significant improvements in academic performance as measured by the school-based annual examination results, regardless of whether they received all three solar products or only one. To detect a possible channel that hindered the effectiveness of solar lanterns, we further explored whether the treated households actually used the solar lanterns, particularly for their children’s nighttime study. We found that the treated students significantly increased their number of study hours, particularly at night and before exams and that they relied more on solar lanterns than on kerosene lamps. Furthermore, their school attendance initially increased for several months after the provision of the solar products; however, this effect disappeared over time. These increased education inputs (i.e., study hours and attendance rates), however, did not translate into improved educational achievements. Based on careful field observations and empirical findings provided by several exercises performed in this study, we provided evidence suggesting that the “no academic performance effects” are not attributable to the possible misuse of the products and spillover effects resulting from the within-grade randomization.

Consequently, an attempt to improve home-study facilities by providing solar lanterns alone did not result in (at least, short-term) positive impacts on children’s educational achievement. Notably, this finding was obtained in our study setting, whereby students’ marginal educational returns to solar products might have been the greatest due to their limited access to electricity at the time of intervention. This conclusion may suggest that unless other education-related inputs are also improved, it is difficult to systematically improve children’s academic performance in the developing world through alleviating only one educational constraint. While we cannot entirely rule out other possibilities responsible for the absence of the positive academic performance effects, the limited effectiveness of education-related interventions that insufficiently consider complementarity across educational inputs has recently been widely observed in other settings (e.g., Glewwe et al. 2004; Glewwe et al. 2009; Mo et al. 2013).

This study is most closely related to Furukawa (2014) and Hassan and Lucchino (2016), wherein RCTs were conducted and the impact of solar lanterns on children’s education was examined. Like us, Furukawa (2014) found an increase in study time, but no positive (or even negative) impacts on the test scores of children belonging to the 5<sup>_th_</sup> and 7<sup>_th_</sup> grades in Uganda. Furukawa (2014) suggested explanations for this finding: reporting bias resulting from the lack of any time-keeping device (e.g., a watch or clock) to measure study time at home; a decrease in study productivity because of a failure to fully re-charge solar products, causing the light to flicker; and intra-household conflicts about 4