世界银行-利用价格激励约束即付即用式太阳能电力的福利效应 Using Price Incentives to Bound Welfare from Pay-as-You-Go Solar Electricity

PublicDisclosureAuthorizedPublicDisclosureAuthorized

PoLicyREsEARcHWoRkiNGPApER11374

UsingPriceIncentivestoBoundWelfarefromPay-as-You-GoSolarElectricity

MeganLang

WORLDBANKGROUP

DevelopmentEconomics

DevelopmentResearchGroupMay2026

Repr◎ducibleResearchRepository

Averifiedreproducibilitypackageforthispaperisavailableat

,click

here

fordirectaccess.

ProducedbytheResearchSupportTeam

PoLIcyREsEARcHWoRkINGPApER11374

Abstract

Non-pricebarrierssuppressdemandattheadoptionmargin,complicatingeffortstoquantifythewelfareeffectsofruralelectrification.Thispaperstudiesdemandforpay-as-you-go(PAYGo)solarelectricityusingarandomizedexperimentwith800existingPAYGocustomersinKenyaandRwandapost-adoption.Theexperimentrandomlyassignsincen-tivesthatlowertheeffectivepriceofusageforconsumerswhomeetmonthlypurchasethresholds.Althoughaver-agedemandisunchanged,consumerswiththehighest

pre-experimentaldemandincreasetheirpurchasesby6–7%inresponsetotheincentive.TheseresponsesareusedtoestimatealowerboundonconsumersurplusfromPAYGosolar.Thestudyfindslargegainsforhigh-demandconsum-ers,butbenefitsdeterioratesubstantiallyforlow-demandconsumers.Combiningtheseestimateswithevidencefromtheliteratureontheenvironmentalexternalitiesofsolarhomesystems,themarginalvalueofpublicfundsofPAYGosolarsubsidiesisatmost1.7inKenyaand2inRwanda.

ThispaperisaproductoftheDevelopmentResearchGroup,DevelopmentEconomics.ItispartofalargereffortbytheWorldBanktoprovideopenaccesstoitsresearchandmakeacontributiontodevelopmentpolicydiscussionsaroundtheworld.PolicyResearchWorkingPapersarealsopostedontheWebat

/prwp.Theauthorsmay

becontactedatmlang@.Averifiedreproducibilitypackageforthispaperisavailableat

http://reproducibility.

,click

here

fordirectaccess.

Y

A

C

P

I

L

E

O

R

P

S

H

W

C

O

R

R

A

K

E

I

RES

TRANSPARENT

ANALYSIS

NGP

ThePolicyResearchWorkingPaperSeriesdisseminatesthefindingsofworkinprogresstoencouragetheexchangeofideasaboutdevelopmentissues.Anobjectiveoftheseriesistogetthefindingsoutquickly,evenifthepresentationsarelessthanfullypolished.Thepaperscarrythenamesoftheauthorsandshouldbecitedaccordingly.Thefindings,interpretations,andconclusionsexpressedinthispaperareentirelythoseoftheauthors.TheydonotnecessarilyrepresenttheviewsoftheInternationalBankforReconstructionandDevelopment/WorldBankanditsaffiliatedorganizations,orthoseoftheExecutiveDirectorsoftheWorldBankorthegovernmentstheyrepresent.

UsingPriceIncentivestoBoundWelfarefromPay-as-You-GoSolar

Electricity

MeganLang

∗

AuthorizedfordistributionbyFlorenceKondylis,ResearchManager,DevelopmentResearchGroup,WorldBankGroup

Keywords:Electricityaccess,welfare,solar.

JELCodes:D1,D6,H2,O2,Q4.

∗WorldBankDevelopmentResearchGroup.Correspondencemaybesent

tomlang@.This

projectwassupportedwithagrantfromtheInternationalGrowthCentre,projectnumber38432.Theopinionsandcon-clusionsexpressedhereinaresolelythoseoftheauthorsandshouldnotbeconstruedasrepresentingtheopinionsorpoliciesofthesponsoringagencies.Theauthorthanksanonymousreviewers,theIGCRwandateam,particularlyDerekApell,aswellasEthanLigon,JeremyMagruder,ElisabethSadoulet,AlaindeJanvry,MarcoGonzalez-Navarro,AprajitMahajan,EdwardMiguel,andtheparticipantsattheUCBerkeleydevelopmentlunchseriesanddevelopmentworkshopseriesfortheirsuggestions.ThankstoAndrewKent,AnthonyMabonga,andPhilipSendifortheircollaborationandassistancewithimplementation.Thisstudyispre-registeredwiththeAEAregistry(AEARCTR-0003138).IthasapprovalfromtheRwandanNationalEthicsCommittee(No.0018/RNEC/2019)andIRBapprovalintheU.S.(U.C.BerkeleyCPHS2018-02-10770).

1

1Introduction

Providinguniversalaccesstoelectricityrequireselectrifyingincreasinglyremoteandlow-incomehouseholds.However,thesehouseholdstypicallyhavelowdemandforelectricity(e.g.,Lee,Miguel,andWolfram

2020

,Grimm,Lenz,etal.

2020

,Burgessetal.

2025

).Itisunclearwhetherthislowobserveddemandforelectricityaccuratelyreflectsthewelfareconsumersgainfromelectrification.Forinstance,creditconstraintscouldbindforhighupfrontconnectioncostsorappliancepurchases,depressingdemandevenifconsumershaveahighvalueforelectrification.Consumersmayalsofaceuncertaintyaboutlowpowerqualityandpoorongoingmaintenance,orsimplyfacebureaucratichurdlestoconnecting.Allofthesenon-pricefactorsshapeobserveddemand,makingitdifficulttoaccuratelyassessthewelfareeffectsofruralelectrification.Understandingthetruevalueconsumersplaceonelectricityiscriticalfordeterminingwhetherthehighcostsofruralelectrificationareajustifiableandefficientuseofpublicresources.

Payasyougo(PAYGo)solarhomesystemsaddressmanyofthebarriersthatpreventhouseholdsfromadoptingelectricity.PAYGocontractsspreadoutpaymentsovertime.Consumersmakeasmalldownpaymenttohaveasolarhomesystem(SHS)installed,whichincludessolarpanelsandallofthebasicappliancesconsumerscanusewiththesystem.Consumerspayoffthesystembypurchasingaccesstime:timewhentheycanusetheelectricitygeneratedbythesystem.Whenaconsumer’saccesstimerunsout,thesolarcompanyremotelylocksthemoutofthesystemuntiltheypurchasemore.Remotelockoutprovidesalow-costenforcementmechanismthatenablesoff-gridcompaniestocontractwithrural,potentiallylow-incomeconsumers.Thecontractalsoincludesafter-salesservice.Lowpopulationdensityinruralareasandlimiteddemandamonglow-incomehouseholdsmakebasicsolarhomesystemstheleast-costoptionformanyunelectrifiedareas(InternationalEnergyAgency

2017

).Suchsystemsdonotincurthecostsofexpandingthegridandaresufficienttoprovidethelimitedenergyservicesthatmanylow-incomehouseholdsdemandintheshort-tomedium-term.StudyingdemandforelectricityusingtheongoingpaymentsforPAYGosolarhomesystemsthereforereducesmanyconcernsaboutusingobserveddemandtoestimatewelfarefromelectrification.

IbounddemandforPAYGosolarusingincentivesofferedbyasolarcompanyto800randomlyselected,existingcustomersinKenyaandRwanda.Theincentiveschangetheeffectivepricepaid

2

foraccesstimebygivingcustomersfreedaysattheendofeachmonthiftheirtotalmonthlypurchasesarehighenough.Byrandomizingtheamountoffreetimeprovided,Iobserveconsumerresponsestodifferenteffectiveprices,essentiallytracingoutademandcurve.Icanthereforeuseestimatedaveragetreatmenteffectsandcounterfactualdemandinthecontrolgrouptoestimateboundsonconsumersurplusfromelectricity.

Onaverage,consumersinKenyaandRwandadonotsignificantlyincreasedemandinresponsetotheincentive.However,consumerswiththehighestpre-experimentaldemandinbothcountriesmodestlyincreasepurchasesby6-7%.TouseconsumerresponsestotheincentivestoboundconsumersurplusfromPAYGosolar,Ineedtoensurethattheyreflectconsumerresponsestopricechangesratherthanotherattributesoftheincentives.Iusesurveydatatodemonstratethatliquidityconstraintsarenotdrivingmyresults.Detailedusagedatashowthatalthoughconsumersengageinminoramountsofintertemporalsubstitution,themagnitudesarenotlargeenoughtoexplainsmallresponsestotheincentives.Icannotruleoutthatconsumersmayrespondtotheinformationcontainedintheincentives,butIshowthatsuchresponseswouldbiasmyestimatesofconsumersurplusdownward.Finally,Ishowthattheempiricalpatternsintreatmenteffectsbetweendistrictswithahighproportionversusalowproportionoftreatedconsumersarenotconsistentwithspilloversbetweenhouseholds.IthusarguethatconsumerresponsestotheincentivesareacrediblerevealedpreferencemeasurethatIcanusetoderivealowerboundonconsumersurplus.

Myresultssuggestthathigh-demandconsumershaverelativelyinelasticdemandforelectricity.InKenya,mylowerboundonconsumersurplusindicatesthathigh-demandconsumersbenefitbyatleast$19permonth.PAYGosolarisrelativelymoreexpensiveinRwanda,somylowerboundofconsumersurplusforhigh-demandconsumersisjust$4.However,demanddropssteeplyforconsumerswithmoderatetolowusage.Thisresultsinmylowerboundonauerageconsumersurplusfallinginlinewithexistingestimatesinbothcountries,butmyestimatesofconsumersurplusforhigh-demandconsumersbeingsubstantiallyhigher.

AlthoughIlackexperimentalvariationtoestimateproducersurplus,Icalculaterangesofpro-ducersurplusunderdifferentassumptionsabouttheamountofaccesstimetheaverageconsumerwouldneedtopurchaseforthefirmtobreakeven.MymostconservativeestimatesimplynegativeproducersurplusoverthelifeofaPAYGocontractofupto$29inKenyaand$34inRwanda.

3

Evenaccountingfornegativeproducersurplusandusingconservativelowerboundsonconsumersurplus,IfindthatPAYGosolarincreasessocialwelfarebyover$300perSHSinKenyaand$40perSHSinRwanda.

Despitebeingmoreaffordablethangridexpansion,PAYGosolarhomesystemsremainexpen-siverelativetotraditionalenergysources.Consumersatthe75thpercentileofenergyexpendituresinruralRwandaspendjustRWF200perweekonenergyservicesthatcouldbereplacedbyabasicsolarhomesystem,whilepurchasingaweekofPAYGoaccesstimecostsroughlyRWF900.

1

ThegapissmallerbutstillsubstantialinruralKenya:aroundKES110perweekfortraditionalenergysourcesrelativetoKES140foraweekofaccesstime.SuchgapsinaffordabilityhavepromptedgovernmentsthroughoutAfricatoconsidersubsidizingsolarhomesystems.

2

IthereforeconsiderwhatmyresultsimplyaboutthevalueofsubsidiesforPAYGosolar.Icalculatethemarginalvalueofpublicfunds(MVPF)foraPAYGosolarsubsidyusingmylowerboundsonconsumersurplus,estimatesfromtheliteratureontheexternalitiesfromsolarhomesystems,mybackoftheenve-lopecalculationofproducersurplus,andinformationabouttaxratesandspendingonalternativeenergysources(HendrenandSprung-Keyser

2020

,Hahnetal.

2024

).IfindthattheMVPFisatmost1.7inKenyaand2inRwanda,butaccountingfornegativeproducersurplusbringsitdownto0.8inKenyaand0.6inRwanda.TheseestimatesimplythattheMVPFforsolarsubsidiesfallsomewhatbelowotherredistributivepoliciesinbothcountries.

Myresultscontributeevidenceonthewelfareimpactsofruralelectrification.Muchoftheliteratureonelectricityaccesshasfocusedonestimatingtheimpactsofelectrificationonarangeofeconomicoutcomes,butresultshavebeenheavilymixed.Grimm,Munyehirwe,etal.(

2016

)andLenzetal.(

2017

)bothfindsomepositiveimpactsfromelectrificationinRwandaintheformofre-ducedenergyexpenditures,healthimprovements,andreduceduseofdrycellbatteries,butBensch,Kluve,andPeters(

2011

)findnopositiveimpactsonincomeorenergyexpenditures.InTanzania,Chaplinetal.(

2017

)findthatelectrificationincreasesincomegeneratingactivitiesandpercapitaconsumptionbuthasnegativeimpactsonhealth.Conversely,Lipscomb,A.MushfiqMobarak,

1AlthoughpartofthisgapisduetotheappliancefinancingincludedinaPAYGocontract,itisworthnotingthattheappliancesincludedinabasicsolarhomesystemtypicallyonlyincludelightbulbs,phonechargers,andradiosortorches.Apartfromlightbulbs,manynon-electrifiedhouseholdspayfordisposableradio/torchbatteriesandphonechargingservices.

2SeeforinstanceTogo(Mumbere2019),Nigeria(AfricaOil+GasReport

2025

),Kenya(Energy4Impact

2025

),andRwanda(RwandaMinistryofInfrastructure

2020

).NotethatsubsidiesinKenyaandRwandadidnotstartuntilaftermyexperimentalperiod.

4

andBarham(

2013

)andDinkelman(

2011

)bothfindthatelectrificationleadstoimprovementsineconomicdevelopmentinBrazilandSouthAfrica,respectively.Walleetal.(

2015

)andKhandkeretal.(

2014

)findpositiveimpactsofelectrificationonconsumptionandBurligandPreonas(

2024

)documentpositiveimpactsforlargeenoughvillagesinIndia,butnoimpactsforsmallervillages.Parsingtheseresultsisdifficultduetodifferencesinsettings,theoutcomesbeingmeasured,anddifferenttimescalesbetweenelectrificationandmeasurement.

Revealedpreferencemeasuresofconsumersurplusaddressmanyconcernsaboutapproachesthatuseselectedeconomicoutcomesasproxiesforwelfareimpacts.Grimm,Lenz,etal.(

2020

),Lee,Miguel,andWolfram(

2020

),andBurgessetal.(

2025

)usepricevariationtoderiverevealedpreferenceestimatesofthewelfareimpactsofelectrification.Ingeneral,theyfindthatconsumerdemandforruralelectrificationislowandrelativelyelastic,implyinglowimpactsonconsumersurplus.However,allthreeexamineelectricityadoption,whichmaybeshapedbymultiplenon-pricefactorsthatcomplicateinterpretationsforwelfare.MystudyaddressestheseconcernsbecauseIstudydemandpost-adoption,whenconsumersareusingandenjoyingthebenefitsofelectrificationratherthansimplyanticipatingthem.Assuch,consumershavealreadylearnedaboutthebenefitsandreliabilityofthetechnology.Althoughconsumersinmysamplemakeasmalldownpaymenttoadoptasolarhomesystem,thevariationIstudycomesfromongoingpaymentsforuse.Thesepaymentsareextremelysmallrelativetotheadoptioncostsstudiedinmuchoftheliterature,addressingconcernsaboutcreditconstraints.Mysettingisalsoonewhereconsumersenjoyafter-salessupportforongoingmaintenanceandwhereappliancesareincludedwiththesystem.Ithereforecontributealowerboundontheconsumersurplusbenefitsofruralelectrificationbyleveragingvariationontheusageratherthanadoptionmarginandbystudyingacontextthatreducesconcernsaboutothernon-pricefactorsthatmaycomplicatemeasurementofconsumersurplus.

Finally,Imakeamodestcontributionbydocumentingpatternsinconsumers’useofelectricity,providingnovel,granularinsightsintotheenergyconsumptionbehavioroflow-incomehouseholds.Ishowthatconsumersengageinlimitedintertemporalsubstitutionofelectricityevenwhentheyhaverechargeableappliances.Thishasimplicationsfordiscussionsofreliability.ConsumersinmysettingreceivemultipleSMSremindersaboutimpendingremotelockoutsbutstilldonotengageinsubstantialintertemporalsubstitution.Thisindicatesthatthereislimitedscopeforintertemporal

5

substitutionamongconsumerswithlowdemandforelectricity,implyingthatunpredictableoutageslikelyhavesignificantwelfarecostsevenforhouseholdsusingsmallquantitiesofelectricity.MyfindingsalignwiththoseinCiss´e(

2025

),whofindssubstantialincreasesinwillingnesstopayformorereliableelectricity,aswellasAlberini,Steinbuks,andTimilsina(

2020

)andGertler,Lee,andAMushfiqMobarak(

2017

).

Designingeffectiveandefficientpoliciestoachieveuniversalelectrificationhingesonaclearunderstandingofconsumerdemand.BypresentingnovelexperimentalevidencefromtheusagemarginofPAYGodemand,IfindthatthewelfaregainsfromPAYGosolararesubstantialbutthemarginalvalueofpublicfundstoexpandaccessfurtherisrelativelylow.Suchevidenceprovidesakeyparameterforcalibratingsubsidiesandoffersanewperspectiveonthevalueofbasic,modernenergyforrural,low-incomehouseholds.

2Background

ThePAYGosystemsIstudyincludesolarpanels,abatteryforstoringpower,andalloftheappliancestobeusedwiththesystemexceptmobilephones.

3

Thesmallestsolarhomesystemsincludethreelightbulbs,aphonecharger,andthechoiceofanadditionallightbulb,arechargeabletorch,orarechargeableradio.Consumerscanincludeadditionalappliancesforahigherprice.Thebatteriesincludedinthesystemarelargeenoughtomakethesystemsareliablesourceofelectricityinspiteoftheirrelativelysmallgenerationcapacity.

Consumersmakeasmalldownpaymenttohavethesolarhomesysteminstalled.Thesolarcompanyaddsupthetotalvalueofthesystemandtheappliancesplusaflatfee,thenconvertsthetotalvalueofthecontractintoadailypriceforsolaraccess.Onceahouseholdhasasolarhomesysteminstalled,theconsumerprepaysforsolaraccesstimeusingmobilemoney.Accesstimeissimplytimewhentheconsumercanusetheelectricitybeinggeneratedbythesolarhomesystemorstoredinthebattery.

Accesstimerunsdowncontinuously,regardlessofsystemuse.Consumerscannotopttoturntheirsystemoffandsaveaccesstimeforlateruse,transfermoneyoutoftheirsolaraccount,ortransferaccesstimetoothersolarconsumers.Whenaconsumerrunsoutofaccesstime,thesolar

3Mobilephonescanbechargedusingthesolarhomesystem,butthephonesarenottypicallyincludedinthepackageofappliancesthattheconsumerpurchasesfromthesolarcompany.

6

companyremotelyswitchesofftheirsystemuntiltheymakeanotherpayment.Whenthesystemisswitchedoff,theconsumercannotaccessanyoftheelectricitybeinggeneratedbythesystemorelectricitystoredinthebattery.Prolongedperiodsofnon-paymentleadtorepossession.Ingeneral,consumerscanpurchaseaccesstimeinanyincrement.

4

Onaverage,consumersusefiftywatthours(wH)ondayswhentheyhavepurchasedaccesstotheirsolarhomesystemsinKenyaandforty-fivewHinRwanda.

5

InKenya,themedianpurchasesizeamongthesampleofconsumersinmyexperimentissixdaysofaccesstime,inRwandaitissevendays.Nearlyhalfofconsumersinbothcountriespurchasesolaraccesson95%ormoreofdayspriortotheexperiment.Around20%purchaseaccessfor85%-95%ofdays,andtheremaining30%purchaselessthan85%ofdays.

DatafromaphonesurveyofPAYGoconsumersinRwandasuggeststhatPAYGoconsumerspositivelyself-selectonwealth(see

FigureA1

).Thus,althoughPAYGocontractsmakesolarhomesystemsmorefinanciallyaccessiblethantheywouldbeifconsumershadtobuythemoutright,theystillservearelativelywealthysegmentoftheruralpopulation.ThisisconsistentwiththecostofPAYGoaccesstimecomparedtotraditionalenergysources,andalignswithevidencefromBenin(BarryandCreti

2020

)andEastAfrica(CollingsandMunyehirwe

2016

,Muchunkuetal.

2018

,Groenewoudt,Romijn,andAlkemade

2020

).Energyservicesreplaceablebyasolarhomesystemcomprisejust0.7%oftotalexpendituresforthemedianruralhouseholdwithoutelectricityaccessinRwanda.Payingforjust5daysaweekofaccesstimeforthemostbasicsolarhomesystemwouldcomprisenearly11%oftotalexpenditures(NationalInstituteofStatisticsofRwanda

December

2017

).

SelectionmaybelessextremeinKenya,althoughIlackanalogousphonesurveydatatotestthisdirectly.However,replaceableexpenditurescomprisejust0.5%oftotalexpendituresforthemedianrural,unconnectedhousehold,andpurchasing5daysaweekofaccesstimewouldonlyincreasetheshareofexpendituresto3%(KenyaNationalBureauofStatistics

2016

).

Atthetimeofmyexperiment,thegovernmentsofKenyaandRwandawerenotdirectlysub-sidizingsolarhomesystems.Myresultsthereforespeaktodemandamongconsumersableto

4Theoneexceptiontoincrementalpurchasesisthatonceconsumers’systemsareswitchedof,theyneedtopurchaseatleastoneweektohavethesystemswitchedbackon.

5Appliancesusedwiththesolarhomesystemareefficient,soconsumerbenefitfromfiftywHmorethanwouldbeexpectedweretheytouselessefficientappliances.

7

purchasesolarhomesystemsatmarketprices.Lower-usageconsumersinmysampleprovidearoughsenseofhowdemandmaychangeforconsumersonthemarginsofelectrification,whomaybeinducedtoadoptasolarhomesystemunderasubsidyregime.

3ExperimentalDesign

Icollaboratedwiththesolarcompanytoofferincentivesforaccesstimepurchasestorandomlyselectedcustomersfor7–8monthsin2018–2019.Mycoreanalysisconcernsincentivesstructuredasamonthlyreward.Ifconsumersboughtatleastfourweeksoverthecourseofamonth,theywouldreceiveeither1or2daysofaccesstimeforfree,withthebonuslevelbeingdeterminedrandomly.

6

Oneconcernaboutthetreatmentisthattheincentivesmaysimplyprovideinformationabouthowtoremainingoodstandingwiththesolarcompany.Forconsumerswhoareuncertainabouttheriskofrepossession,theincentivesmaychangebehaviorpurelythroughthisinformationchannelratherthanapricechannel.Toaddresssuchconcerns,thesolarcompanyalsoimplementedasimpleinformationtreatmentwhererandomlyselectedconsumersreceivedaphonecallfromthesolarcompanyinformingthemhowmanydaysamonththeyneedtopurchasetobeconsidereda“goodcustomer”.

Inbothcountries,pre-experimentalmeanandmediandemandwerearound20–21days.

7

Con-sumersfacedascheduleofincentives,withincentivesincreasinginthenumberofweekspurchased(see

FigureA3

).Inpractice,fewconsumersqualifiedforanythingabovetheminimumnumberofbonusdays.

Intotal,thecompanyoffered400consumersthemonthlyrewardinbothRwandaandKenya.Itimplementedtheinformationtreatmentwithanadditional400consumers.Mycontrolgroupincludes5198randomlyselectedconsumersinRwandaand3800randomlyselectedconsumersinKenya.Istratifiedthesamplebasedonaconsumers’utilizationrateatthestartoftheexperiment:theproportionofdaysaconsumerhashadaccesstotheirsolarhomesystem.Icreatedfivestratabasedonpre-experimentaldemand:65%andbelow,65%–75%,75%–85%,85%–95%,and

6Thesolarcompanysimultaneouslypilotedotherincentiveswithhigherqualifyingthresholdsandincentivesstruc-turedasbulkdiscountsonindividualpurchasesofaccesstime.Theseincentivesarenotinformativefortheconsumersurplusexercise.Forcompleteness,Ipresentthepre-registeredresultsonallincentivetypesin

AppendixE

.

7

FigureA2

showsthedistributionofmeandaysofaccesstimepurchasedinamonthduringthe4monthspriortotheexperimentinRwandaandduringthe5monthspriortotheexperimentinKenya.

8

above95%.Inbothcountries,thestratificationensuresthatIoversampleconsumerswithlowpre-experimentaldemand.However,sinceIstratifiedmyentiresample,consumersineachstratumfacethesameprobabilityoftreatment.Randomassignmentgenerallyyieldsbalancealonganumberofpre-experimentalcovariates,thoughthereisslightimbalanceinTVownershipinbothcountries,inthedailyrateinRwanda,andinpre-experimentaldemandinKenya(see

TableA1

and

TableA2

).Giventhatmyprimaryspecificationusespaneldatawithconsumer-levelfixedeffects,imbalanceonthesecovariatesshouldnotbiasmyresults.

Arepresentativefromthesolarcompanycalledeachconsumerwhohadbeenselectedforeithertheincentivesortheinformationtreatmentinthetwoweekspriortothestartoftheexperiment.Oncetheexperimentstarted,consumersintheincentivetreatmentreceivedweeklySMSmes-sageswithdetailedremindersabouttheincentives.TheexperimentranfromJuly,2018throughFebruary,2019inRwandaandfromAugust,2018throughFebruary,2019inKenya.

8

3.1Data

ThroughoutmyanalysisIprimarilyrelyonadministrativedataobtainedfromthesolarcompanytoexamineconsumerresponsestotheincentivesandinformation.TheadministrativedatastartinMarch,2018andcontinuethroughtheendoftheexperimentinFebruary,2019,providinga4-monthpre-periodinRwandaanda5-monthpre-periodinKenya.Iobserveallpaymentsforsolaraccesstime,bonusdaysearned,thepre-experimentalutilizationrate,thedailyrate,dailytotalsofwatthoursused,andtheappliancesincludedineachconsumer’ssolarhomesystem.

Fordescriptivepurposes,Ialsoleverageaphonesurveyconductedaftertheendoftheex-perimentwitharandomsubsetofconsumersinRwandainMarch2019.Thephonesurveywasconductedbyanindependentteamofenumerators,whocalled800respondentsinthecontrolgroupandalltreatedconsumers.Responserateswerelowatjust61.86%.

9

Giventherelativelylowresponserates,Iinterpretresultsusingthephonesurveydatawithcaution.

8ConsumerscouldstillearnthebonusinFebruaryeventhoughtherewereonly28days:thebonusdaysweresimplyaddedtotheiraccounttouseinMarch.Ishowin

TableA3

thataveragetreatmentefectsarerobusttoexcludingFebruary.

9Enumeratorsreportedthatitwasmoredifficulttoreachconsumersinmoreremoteareaswherethecellularnetworkislessreliable.Ialsoseethatresponseratesareincreasinginpre-experimentaldemand,withconsumersinthe95%–100%stratumbeing6.9ppmorelikelytorespondtothephonesurveythanconsumersinthe0%–65%stratum.

9

3.2EmpiricalStrategy

Iestimatereducedformaveragetreatmenteffectsusingthespecification

DaysPurchasedit=α+β1Incentiveit+β2Infoit+γt+γi+ϵit.(1)

DaysPurchaseditisthenumberofdaysofaccesstimepurchasedbyconsumeriinmontht,notinclusiveofbonusdays.IncentiveitisadummyvariableequaltooneifconsumeriinmonthtwasassignedtothemonthlyrewardtreatmentandInfoitisadummyvariableequaltooneiftheywereassignedtotheinformationtreatment.Notethatbothtreatmentindicatorsarezeroduringthepre-period,switchoninthefirstmonthoftreatment,andremainswitchedonduringallsubsequentmonthsoftheexperiment(i.e.,treatmentneverturns“off”foranyconsumeruntiltheexperimentconcludes