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Output by prefecture

Solar Output per kW by Prefecture in Japan

Estimated annual output per kW (kWh) from JMA radiation and temperature normals (1991–2020), using this site's method. Highest: Nagano 1,387, Yamanashi 1,380, Shizuoka 1,329, Miyazaki 1,319, Kochi 1,319. Lowest: Toyama 1,114, Ishikawa 1,114, Akita 1,092.

Annual output (kWh per kW)

Prefecture	Year (22°, south)	31°, south	22°, east/west	For 5 kW	Station
Hokkaido	1,194	1,215	1,015	5,972	Sapporo
Aomori	1,117	1,121	949	5,584	Aomori
Iwate	1,169	1,184	994	5,847	Morioka
Miyagi	1,200	1,219	1,020	6,001	Sendai
Akita	1,092	1,093	929	5,462	Akita
Yamagata	1,152	1,158	980	5,762	Yamagata
Fukushima	1,170	1,183	995	5,851	Fukushima
Ibaraki	1,265	1,281	1,075	6,326	Tsukuba
Tochigi	1,240	1,261	1,054	6,201	Utsunomiya
Gunma	1,294	1,315	1,100	6,469	Maebashi
Saitama	1,183	1,196	1,005	5,913	Tokyo
Chiba	1,288	1,298	1,094	6,438	Choshi
Tokyo	1,183	1,196	1,005	5,913	Tokyo
Kanagawa	1,183	1,196	1,005	5,913	Tokyo
Niigata	1,121	1,119	953	5,606	Niigata
Toyama	1,114	1,113	947	5,572	Toyama
Ishikawa	1,114	1,113	947	5,572	Toyama
Fukui	1,136	1,134	965	5,679	Fukui
Yamanashi	1,380	1,400	1,173	6,902	Kofu
Nagano	1,387	1,402	1,179	6,936	Nagano
Gifu	1,306	1,321	1,110	6,532	Nagoya
Shizuoka	1,329	1,346	1,130	6,646	Shizuoka
Aichi	1,306	1,321	1,110	6,532	Nagoya
Mie	1,306	1,321	1,110	6,532	Nagoya
Shiga	1,195	1,197	1,016	5,975	Hikone
Kyoto	1,232	1,237	1,047	6,161	Osaka
Osaka	1,232	1,237	1,047	6,161	Osaka
Hyogo	1,232	1,237	1,047	6,161	Osaka
Nara	1,188	1,191	1,010	5,941	Nara
Wakayama	1,232	1,237	1,047	6,161	Osaka
Tottori	1,153	1,149	980	5,766	Matsue
Shimane	1,153	1,149	980	5,766	Matsue
Okayama	1,264	1,267	1,074	6,318	Takamatsu
Hiroshima	1,270	1,278	1,080	6,352	Hiroshima
Yamaguchi	1,197	1,196	1,018	5,986	Shimonoseki
Tokushima	1,264	1,267	1,074	6,318	Takamatsu
Kagawa	1,264	1,267	1,074	6,318	Takamatsu
Ehime	1,267	1,271	1,077	6,336	Matsuyama
Kochi	1,319	1,331	1,121	6,594	Kochi
Fukuoka	1,200	1,200	1,020	5,999	Fukuoka
Saga	1,195	1,199	1,016	5,977	Saga
Nagasaki	1,217	1,216	1,035	6,086	Nagasaki
Kumamoto	1,254	1,257	1,066	6,272	Kumamoto
Oita	1,203	1,207	1,023	6,016	Oita
Miyazaki	1,319	1,326	1,121	6,595	Miyazaki
Kagoshima	1,259	1,261	1,070	6,294	Kagoshima
Okinawa	1,228	1,211	1,044	6,140	Naha

4-sun ≈ 22°, 6-sun ≈ 31°. "For 5 kW" is the annual output of a 5 kW south-facing system at 22°. No shading assumed.

Monthly output (22°, south, kWh per kW)

Prefecture	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Hokkaido	70	84	114	123	133	126	120	114	102	88	63	58
Aomori	51	69	101	120	132	125	119	117	102	86	53	42
Iwate	79	90	114	118	126	117	106	107	92	87	69	63
Miyagi	92	99	119	125	125	105	96	100	88	90	82	79
Akita	46	62	99	119	125	121	109	120	104	91	56	39
Yamagata	69	84	107	120	129	118	109	114	95	86	65	56
Fukushima	84	94	118	123	126	106	98	103	87	85	75	71
Ibaraki	107	105	118	121	125	104	111	117	95	88	84	91
Tochigi	107	108	121	121	121	99	98	104	90	89	88	95
Gunma	109	111	128	127	126	103	105	110	91	93	93	98
Saitama	100	98	110	116	119	96	103	108	85	81	81	87
Chiba	98	96	112	124	130	111	123	134	105	88	81	85
Tokyo	100	98	110	116	119	96	103	108	85	81	81	87
Kanagawa	100	98	110	116	119	96	103	108	85	81	81	87
Niigata	51	66	100	121	133	121	114	124	101	87	58	43
Toyama	57	72	99	116	128	112	110	123	97	89	64	48
Ishikawa	57	72	99	116	128	112	110	123	97	89	64	48
Fukui	56	72	102	117	127	109	110	125	101	95	70	51
Yamanashi	111	114	131	132	134	113	119	128	104	99	96	100
Nagano	96	105	127	137	147	129	124	130	111	104	91	86
Gifu	100	106	125	126	128	107	110	121	101	100	92	91
Shizuoka	109	108	121	124	128	106	114	127	104	96	94	99
Aichi	100	106	125	126	128	107	110	121	101	100	92	91
Mie	100	106	125	126	128	107	110	121	101	100	92	91
Shiga	69	80	110	119	127	109	113	126	103	96	78	64
Kyoto	84	86	110	120	126	107	115	125	100	96	83	79
Osaka	84	86	110	120	126	107	115	125	100	96	83	79
Hyogo	84	86	110	120	126	107	115	125	100	96	83	79
Nara	75	81	106	117	124	102	109	123	100	96	82	73
Wakayama	84	86	110	120	126	107	115	125	100	96	83	79
Tottori	56	70	104	121	135	115	114	123	100	94	71	51
Shimane	56	70	104	121	135	115	114	123	100	94	71	51
Okayama	83	91	114	124	132	111	120	128	102	98	83	79
Hiroshima	87	91	115	122	129	107	113	124	106	107	89	82
Yamaguchi	65	79	110	121	129	106	113	124	105	105	80	63
Tokushima	83	91	114	124	132	111	120	128	102	98	83	79
Kagawa	83	91	114	124	132	111	120	128	102	98	83	79
Ehime	82	92	115	123	129	105	119	128	106	105	87	76
Kochi	105	105	120	124	124	100	115	124	104	105	94	98
Fukuoka	71	84	109	120	125	103	110	119	104	105	83	68
Saga	79	86	107	116	119	93	104	116	104	106	86	77
Nagasaki	71	83	110	120	123	96	115	125	108	109	85	72
Kumamoto	82	88	112	121	125	98	114	124	111	109	89	81
Oita	86	90	110	117	120	95	110	117	96	97	82	82
Miyazaki	108	102	117	121	122	93	122	127	105	105	96	101
Kagoshima	87	90	110	118	119	90	117	126	112	112	94	86
Okinawa	76	78	97	102	109	112	131	126	118	110	90	80

Assumptions

Radiation on the roof is derived from horizontal radiation with the Liu–Jordan method (diffuse fraction by Erbs).
Losses (soiling, wiring, inverter) total 12%; module temperature is the monthly mean + 21.5 °C; output falls 0.4% per °C.
Prefectures without a radiation station use a nearby one (Saitama and Kanagawa → Tokyo, Chiba → Choshi, Ibaraki → Tsukuba, Ishikawa → Toyama, Gifu and Mie → Nagoya, Kyoto, Hyogo and Wakayama → Osaka, Tottori → Matsue, Okayama and Tokushima → Takamatsu, Yamaguchi → Shimonoseki).
Output varies within a prefecture, especially in mountains and snowy areas.

Calculate for your home

Sources: radiation and temperature from JMA climate normals (1991–2020); feed-in tariff and renewable surcharge from METI (March 19, 2026); PV system and O&M costs from the Procurement Price Calculation Committee (110th meeting); battery cost from METI (March 2025); default electricity price from the appliance fair trade council. Calculated by this site (checked 2026-11-01). Links are in Japanese.

Solar Output per kW by Prefecture in Japan

Annual output (kWh per kW)

Monthly output (22°, south, kWh per kW)

Assumptions

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