Section 25D expired on 31 December 2025, so a purchased residential system in<\/p>\n
2026 receives no federal credit. Most published payback figures still include<\/p>\n
the 30%, which makes them roughly three to five years too short. I recalculated<\/p>\n
all 50 states without it.<\/p>\n
Data: https:\/\/energycostmap.com\/states.json<\/a><\/p>\n DOI: https:\/\/doi.org\/10.5281\/zenodo.22305313<\/a><\/p>\n Repo: https:\/\/github.com\/chameerasampathkorea\/us-solar-payback-by-state<\/a><\/p>\n Method: https:\/\/energycostmap.com\/methodology\/<\/a><\/p>\n Licence: CC BY 4.0<\/p>\n Fields per state: annual generation (NREL PVWatts v8), retail rate (EIA), export<\/p>\n factor and netting period from the serving utility’s tariff, installed cost,<\/p>\n incentives, simple and degradation-adjusted payback, 25-year net return, plus the<\/p>\n source URL and date the export terms were checked against.<\/p>\n Range: Hawaii 4.1 years to Alabama 24.5. Alabama is the outlier because Alabama<\/p>\n Power bills solar customers $5.41\/kW\/month \u2014 about $390 a year on a 6 kW system,<\/p>\n a charge a federal judge upheld in March 2026.<\/p>\n The field I would point at is nettingPeriod. Before a utility compensates<\/p>\n exported power it nets exports against imports \u2014 over a whole monthly bill in<\/p>\n some states, over fifteen-minute intervals in others. With monthly netting,<\/p>\n power exported at midday offsets power drawn at 7pm at the full retail rate.<\/p>\n Iowa and Oregon both credit exports at 100% of retail, but Iowa nets in<\/p>\n fifteen-minute intervals and Oregon monthly, and Oregon pays back faster despite<\/p>\n weaker irradiance. Almost no published comparison records this field.<\/p>\n Known limitations, also listed in the method: one utility modelled per state<\/p>\n (normally the largest); the retail rate is an EIA state average rather than a<\/p>\n specific tariff; self-consumption is assumed rather than measured; loan interest,<\/p>\n dealer fees, resale premium, leases, batteries and roof replacement are all<\/p>\n excluded.<\/p>\n Happy to answer questions on any state’s figure.<\/p>\n<\/div>\n submitted by \/u\/Ok-Map-7006 <\/a>
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