Solar · guide

How much does a balcony solar panel produce?

A 400 W panel hanging upright on a south-facing railing makes about 377 kWh a year in Tennessee (the middle state for sunshine), worth about $50.53 at its average rate, if you use the power as it’s made. Upright, it catches about 64% of what the same panel would facing south at the best tilt; facing east or west, about 53%.

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A 400 W panel in every state

Upright on a south-facing railing, and tilted at about 30° on a stand facing south, in kWh a year; savings at each state’s average rate (August 2026).

State rules on plug-in solar

Official sources only (state legislature bill pages and enacted text, a governor’s signing release, a utility commission page), checked November 5, 2026. We quote the text; we don’t say what it means for you. Check with your utility before connecting.

States with a law

• Utah law (H.B. 340, 2025; in effect since May 7, 2025) on plug-in solar says: “has a maximum power output of not more than 1,200 watts” … “may not require a customer using a portable solar generation device to:” … “obtain the electrical corporation's approval before installing or using the system”. Check with your utility before connecting. Official source: Utah Legislature, H.B. 340 (2025); checked November 5, 2026.
• Colorado law (HB26-1007, 2026; signed May 7, 2026, in effect since August 12, 2026) on plug-in solar says: “designed or commissioned to supply a maximum power output of not more than one thousand nine hundred twenty watts to the electric grid” … “may require a customer to notify the provider of the customer's use of a portable-scale solar generation device by indicating the presence and size of the device in kilowatts”. Check with your utility before connecting. Official source: Colorado General Assembly, HB26-1007; checked November 5, 2026.
• Connecticut law (H.B. 5340, Public Act 26-127 section 9, 2026; in effect since October 1, 2026) on plug-in solar says: “has a maximum power output of not more than one thousand two hundred watts” … “shall be exempt from any requirement concerning interconnection agreements imposed by any regulation adopted by the Public Utilities Regulatory Authority or any decision of the authority, provided not more than one such device may be used behind a customer's electric meter”. Check with your utility before connecting. Official source: Connecticut General Assembly, Public Act 26-127, text as archived October 1, 2026; checked November 5, 2026.
• Maine law (LD 1730, Chapter 644, 2026; signed April 6, 2026) on plug-in solar says: “with a combined inverter output of up to 420 watts, measured in alternating current, per service address” … “exceeding 420 watts, but no more than 1,200 watts, per service address, as long as each system is installed by an electrician licensed in the State and uses a dedicated circuit with a single outlet and the customer complies with the notification requirement in subsection 5”. Check with your utility before connecting. Official source: Maine Legislature, LD 1730 (132nd); checked November 5, 2026.
• Maryland law (HB 1532, Chapter 353, 2026; signed May 12, 2026) on plug-in solar says: “allows customers to purchase and install not more than one Portable Solar Energy Generating System per electric meter for residential use only, provided the device does not supply more than 1,200 watts and is certified by a nationally recognized testing laboratory” … “Customers must by law, however, notify their electric company before installation”. Check with your utility before connecting. Official source: Maryland Public Service Commission, Balcony Solar; the bill; checked November 5, 2026.
• New Hampshire law (SB 540, Chapter 262, 2026; signed July 2, 2026, takes effect January 1, 2027) on plug-in solar says: “Each metered customer shall be allowed a maximum of one plug-in solar generation system with a maximum inverter output of 1,200 watts AC.” … “Obtain electric distribution utility approval before installing or using the system”. Check with your utility before connecting. Official source: New Hampshire General Court, SB 540 chaptered text; checked November 5, 2026.
• New Jersey law (S2368/A4836, P.L.2026 c.82, 2026; signed September 1, 2026, takes effect March 1, 2027) on plug-in solar says: “The law exempts qualifying plug-in solar devices of up to 1,200 watts” … “from utility interconnection and metering requirements, including certain fees, approvals, and equipment mandates”. Check with your utility before connecting. Official source: New Jersey Legislature, S2368; checked November 5, 2026.
• Virginia law (HB 395, Chapter 1052, 2026; signed April 22, 2026, takes effect January 1, 2027) on plug-in solar says: “has a maximum power output of not more than 1,200 watts per customer or, in the case of multi-family housing, per residential building unit” … “shall notify the electric service provider by submitting the form established by the Commission, online or by mail, prior to the installation of a small portable solar generation device”. Check with your utility before connecting. Official source: Virginia LIS, HB 395 Chapter 1052; checked November 5, 2026.
• California law (SB 868, Chapter 985, 2026; signed September 30, 2026, takes effect January 1, 2027) on plug-in solar says: “Has a maximum aggregated AC output of no more than 1,200 watts per dwelling.” … “may require a customer using a portable solar generation device to notify the electrical corporation or local publicly owned electric utility, using a simple online registration form, of the address, make, model, and size of the portable solar generation device”. Check with your utility before connecting. Official source: California Legislative Information, SB 868, text as archived October 2, 2026; checked November 5, 2026.
• Vermont law (S.202, Act 149, 2026; signed June 16, 2026, in effect since July 1, 2026) on plug-in solar says: “A customer may install one or more plug-in photovoltaic devices per electric meter if the devices have a maximum combined inverter capacity of not more than 1,200 watts.” … “Plug-in photovoltaic devices shall only be connected to systems using smart meters.” … “shall not be required to obtain an interconnection agreement with an electric distribution company”. Check with your utility before connecting. Official source: Vermont General Assembly, S.202 (Act 149), text as archived August 7, 2026; checked November 5, 2026.

Passed, not signed

• New York’s legislature passed a plug-in solar bill (A9111C/S8512C, the SUNNY Act) on May 28, 2026; the official record shows no governor’s signature as of November 5, 2026. We found no state law on plug-in solar in New York as of November 5, 2026; ask your utility. Official record: New York State Assembly, A09111.

Bills pending

• We found no state law on plug-in solar in Massachusetts as of November 5, 2026; ask your utility. A bill (H.5175) is pending: a conference committee was appointed on July 16, 2026 (Massachusetts Legislature, H.5175).
• We found no state law on plug-in solar in Michigan as of November 5, 2026; ask your utility. A bill (HB 5764) is pending: referred to the House Committee on Energy on March 19, 2026 (Michigan Legislature, HB 5764 (2026)).
• We found no state law on plug-in solar in Pennsylvania as of November 5, 2026; ask your utility. A bill (HB 1971) is pending: referred to the House Energy Committee on October 28, 2025 (Pennsylvania General Assembly, HB 1971 (2025-2026)).
• We found no state law on plug-in solar in North Carolina as of November 5, 2026; ask your utility. A bill (House Bill 1129) is pending: referred to the House Rules Committee on April 30, 2026 (North Carolina General Assembly, H1129 (2025-2026)).

Every other state (Alabama, Alaska, Arizona, Arkansas, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Ohio, Oklahoma, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Washington, West Virginia, Wisconsin, Wyoming): we found no state law on plug-in solar as of November 5, 2026; ask your utility. Bills that were introduced and stalled in 2026 aren’t listed.

How we estimate the angle

We take Global Solar Atlas monthly sunshine for each state, move it onto the panel’s angle with a standard isotropic-sky model, and compare it with the best tilt facing south. It’s our estimate, not a measured figure, and it ignores shade from the balcony above, walls and trees, which often matters more.

FAQ

Sources and assumptions

• Solar output (kWh per kW of panels, by month): Global Solar Atlas 2.0, long-term averages to 2025 (data version 2.2.68, updated 2026-04-01), for crystalline-silicon panels facing south at the best fixed tilt, after typical system losses. Data obtained from the “Global Solar Atlas 2.0, a free, web-based application is developed and operated by the company Solargis s.r.o. on behalf of the World Bank Group, utilizing Solargis data, with funding provided by the Energy Sector Management Assistance Program (ESMAP). For additional information: https://globalsolaratlas.info” Licensed CC BY 4.0; we rounded and combined it as described here. Not affiliated with or endorsed by Solargis or the World Bank Group.
• State figure: population-weighted average of the state’s three largest cities (U.S. Census Bureau Vintage 2024 population estimates; coordinates from the 2020 Census Gazetteer). Hawaii and DC use one city.
• Cross-check: NASA POWER sunshine climatology (2001–2025), tilted with a standard isotropic-sky model × 0.80. States more than 12% apart were reviewed by hand; the gaps are explained on our methodology page.
• Home use: EIA Table 5A, 2024 average monthly residential kWh by state. Rates: EIA Electric Power Monthly, August 2026.
• Tax credit: IRS FAQ on the One, Big, Beautiful Bill (FS-2025-05, Aug. 21, 2025).
• Assumptions: 85% charging efficiency into a battery, 85% from battery to appliance, panel counts rounded up, off-grid sizing for the worst month. Balcony factors: our isotropic-sky estimate, described above.