Solar Planning & Design

To size your system, start with two questions: how much electricity you use, and how much roof space you have.

1. Energy usage

The average American household uses around 29–30 kWh of electricity per day, but this varies enormously by region. Homes in the South use up to 38 kWh daily due to heavy air conditioning, while Northeast homes average closer to 23 kWh and rely more on natural gas for heating. State-level averages range from under 17 kWh per day in Hawaii to over 41 kWh in Louisiana. Household size, climate zone, heating and cooling type, and electric vehicle charging all significantly affect consumption. We start with your daily energy usage because it determines how large a solar system you need to meaningfully reduce your electricity bill.

Daily Energy Usage: 40 kWh (~$264.0/month)

5 kWh 100 kWh

Electricity Cost

$ /kWh

Sell Price (FiT)

$ /kWh

Self Use %

%

lightbulb Note: These are simplified estimates. For detailed tariff inputs and advanced calculations, use the full Photonik app.

Representative flat export rate (feed-in tariff). What you earn per kWh of surplus solar exported to the grid. Your actual rate depends on your provider, plan, and time of day.

See how export rates work →

Estimated at 75% of the retail grid rate. A battery lets you store daytime solar and export during expensive peak hours, so each exported kWh is typically worth more than a flat feed-in tariff. Real returns depend on your time-of-use tariff and battery efficiency.

See how export rates work →

2. How many panels can fit on your roof?

How many panels fit depends on your roof size, shape, and orientation. A typical single-family home has 20–40 m² (200–400 sq ft) of usable south-facing roof, fitting 10–20 panels (4–8 kW). Ranch-style homes often have large, accessible roof areas, while two-storey colonials may have less south-facing space. Hip roofs reduce usable area compared to gable designs, and dormers, plumbing vents, HVAC equipment, and skylights all reduce panel space. Fire code setbacks require panels to be positioned 18–36 inches from ridges, eaves, and valleys to provide firefighter access.

Most American homes have asphalt shingle roofs pitched at 4:12 to 8:12 (18–34 degrees), well-suited for standard racking systems using lag bolts and flashing. Tile and metal roofs are common in southern and western states. Installations must comply with NEC Article 690 for PV systems, including rapid shutdown requirements that reduce voltage within 30 seconds of system shutdown. A local building permit and AHJ (Authority Having Jurisdiction) inspection are required, and most utilities require an interconnection agreement before your system can export to the grid.

Loading panel placement tool...

This is a simplified panel layout tool — if you hit issues here, or need multiple groups, shading, or generation calcs, use the full Photonik design tool.

System sizing United States

Solar System Size: 14 (59 kWh/day)

1 kW 20 kW

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A 14 kW system in United States can generate approximately 21420.0 kWh annually based on local sun conditions.

Solar system size

You'll need around 10.5kW of solar to match your average US household consumption. We recommend sizing between 15.8kW and 21.1kW for optimal results, accounting for daily and seasonal variations. Solar generation potential varies significantly across the US, with southwestern states averaging 5-6 kWh/kW/day annually, whilst northeastern states average 3.5-4.5 kWh/kW/day.

A 15.8 kW system in the United States generates approximately 66.2 kWh daily on average, with seasonal variation from 3.15 kWh/kW/day in December to 4.78 kWh/kW/day in August. The US offers excellent solar potential in many regions, making solar a viable investment across most states.

Battery Size: 5 kWh

0 kWh 30 kWh

lightbulb A 0kWh battery will make you about 0% self sufficient.

The sweet spot for most households is 5 – 13 kWh — larger batteries add independence but with diminishing payback, especially where feed-in tariffs are low.

Battery storage

With solar-only (no battery), a 15.8 kW system provides approximately 50% self-usage in the United States, depending on your consumption patterns, drawing 50% from the grid. Adding a 10 kWh battery increases energy independence to approximately 72% annually, reducing grid reliance to 28%. Battery storage is valuable in the US, allowing you to store excess daytime generation for evening use and providing backup power during outages, maximising the value of your solar investment.

A battery stores daytime solar for evening and overnight use, cutting the amount you buy from the grid at retail rates. The value depends on the spread between what you pay for electricity and what your utility credits for exports. For accurate battery savings and ROI calculations specific to your state and utility, use the full Photonik design tool.

System Costs

The overall price of a solar and battery system depends on equipment quality, installation complexity, and any available rebates or incentives.

Estimated price

A 15.8 kW solar system in the United States costs approximately $22,152, while adding a 10 kWh battery increases the total to around $34,872. US solar installation costs average around $3-4 per watt, higher than Australia but competitive globally, with costs varying significantly by state and installer. Solar-only systems typically pay for themselves in around 9.0 years in the United States, whilst adding battery storage usually extends payback but significantly improves energy independence. The federal Investment Tax Credit (ITC) has been phased out, but many states offer tax credits, rebates, and net metering programs that improve returns.

The cost breakdown shows estimates for equipment costs, installation labour, and applicable taxes. Adjust system size and battery storage to see how it affects total investment and payback periods. The US has excellent installer coverage nationwide, with NABCEP-certified installers operating in all states, providing competitive pricing and quality installations.

Equipment quality tier

Tiers follow the same scale as the Photonik app. Browse the panel product directory.

Rebates & incentives

The 30% federal Residential Clean Energy Credit (ITC) for homeowner-purchased solar systems expired at the end of 2025 following the One Big Beautiful Bill Act. There is currently no federal tax credit available for new residential solar installations purchased by homeowners. However, solar leases and power purchase agreements (PPAs) may still benefit from commercial credits passed through by the system owner. Several states offer their own incentives — including SRECs, performance-based payments, and rebate programs — so check your state page for local programs that can reduce your upfront cost.

Payback

Simple payback is the system price divided by annual savings. The price side depends on equipment quality, installation complexity, and rebates. The savings side depends on your electricity usage, the buy rate per kWh, and the feed-in tariff for exported energy.

Simple payback calculation

Estimated price after rebates $27060

Estimated annual savings $1774.0

Calculation $27060 ÷ $1774

Simple payback 6.7 years

Electricity rates & feed-in tariffs

American residential electricity rates range from around 11c/kWh in low-cost states like North Dakota to over 30c/kWh in California, Massachusetts, and Hawaii — the national average is about 17c/kWh. Net metering policies vary widely: around 38 states offer some form of credit for exported solar, with many providing full retail-rate compensation, though states like California have shifted to lower export rates under NEM 3.0. In states with high rates and full net metering, solar payback can be as short as 5–7 years. Where export credits are low or electricity is cheap, batteries and maximising self-consumption become more important for the financial case.