How Much Should a 5kW Solar System Produce Per Month?
Last updated: 2026-04-06 · Solar Benchmark
How Much Should a 5kW Solar System Produce Per Month?
A 5kW solar system produces between 440 and 750 kWh per month, depending on your location, roof orientation, and shading. The US national average is roughly 562 kWh/month — or about 6,750 kWh per year. A 5kW system is one of the most common residential sizes installed before 2020, and many of these systems are now approaching the 5–7 year mark where performance verification becomes more valuable.
Monthly Production Benchmarks for a 5kW System
Expected monthly output for a 5kW system on a south-facing roof at 30-degree tilt, the standard reference configuration for physics-based modeling. Numbers derived from pvlib simulation using Open-Meteo ERA5 historical weather data, averaged across US continental latitudes.
| Month | Expected Production (kWh) | Notes |
|---|---|---|
| January | 338 | Shortest days, lowest sun angle |
| February | 439 | Gradual improvement |
| March | 574 | Spring ramp begins |
| April | 641 | Strong shoulder month |
| May | 709 | Near-peak |
| June | 743 | Peak production month |
| July | 709 | Heat losses reduce versus June |
| August | 675 | Daylight hours falling |
| September | 608 | Fall taper |
| October | 506 | Meaningful drop |
| November | 405 | Low output range |
| December | 338 | Lowest month |
| Annual Total | ~6,750 | US national average |
(Source: pvlib physics modeling, Open-Meteo ERA5 weather data)
What These Numbers Mean
A 5kW system on a typical residential inverter (4.0kW or 5.0kW AC) operates below the clipping threshold that affects larger systems. That means production benchmarks are more straightforward: if the system is well-oriented and unshaded, it should track the table above within 10% in any given month.
The more common issue with 5kW systems is age-related. Many were installed 2016–2020 with PERC panels that degrade at roughly 0.5%/year. A 5kW system installed in 2018 should be expected to produce about 3–4% less than a new installation. At the 10-year mark, that becomes roughly 5%. That degradation is normal. What isn't normal is production falling 15% or more below the age-adjusted expected benchmark.
Regional Variation: 5kW System Annual Production
| Region | Example States | Annual kWh | Monthly Average |
|---|---|---|---|
| Southwest Desert | AZ, NV, inland CA | 9,000 | 750 |
| California Coast | coastal CA | 8,000 | 667 |
| Southeast | FL, TX, GA | 7,500 | 625 |
| Mid-Atlantic | NJ, MD, VA, NC | 6,750 | 562 |
| Midwest | OH, IL, MO | 6,250 | 521 |
| New England | MA, NY, CT | 5,750 | 479 |
| Pacific Northwest | WA, OR | 5,250 | 438 |
(Source: pvlib physics modeling, Open-Meteo ERA5 weather data, averaged 2015–2024)
What Affects a 5kW System's Output
- Age and degradation: A 5kW PERC system installed in 2017 has lost roughly 4–4.5% of its original output to normal degradation. That's expected. A system showing 15%+ below the age-adjusted benchmark has a problem beyond normal wear.
- Roof orientation: South-facing at 30 degrees produces the most. West-facing costs about 13% annually; east-facing costs about 15%. A 5kW west-facing system in New Jersey should expect roughly 4,900–5,100 kWh/year, not 6,750.
- Shading: At 5kW, most systems run 14–17 panels on a single string. One partially shaded panel reduces the whole string's output. Even a chimney shadow that covers 20% of one panel for 3 hours per day can cut annual production by 200–400 kWh.
- Temperature: Hot summer afternoons reduce output. A 5kW system in Phoenix produces less per panel in July than the same system in Denver, despite more sun hours.
- Soiling: Cumulative dust and pollen reduce output 2–5% in most climates, more in dry western summers. Rain resets soiling losses. Long dry spells compound them.
- Microinverter vs. string: 5kW systems installed with microinverters are less vulnerable to partial shading and can be monitored at the panel level. String-wired systems lose more to a single shaded panel.
Frequently Asked Questions
Q: A 5kW system was advertised to me as producing 700 kWh/month. Is that accurate?
A: 700 kWh/month would be the annual average for a 5kW system in coastal California or the Southeast. For most of the Mid-Atlantic, Midwest, and New England, the realistic annual average is 440–560 kWh/month. Summer months will exceed 700 kWh; winter months won't. Installers sometimes quote summer peak production as if it represents the annual average, which it does not.
Q: My 5kW system is 6 years old and producing 580 kWh in June. Should I be worried?
A: For the Mid-Atlantic in June, a new 5kW system should produce around 743 kWh. At 6 years with 0.5%/year degradation, the age-adjusted expectation is about 721 kWh. A reading of 580 kWh is 20% below that. That's outside normal degradation range and warrants an inspection.
Q: How much electricity does a 5kW system offset annually for a typical household?
A: The average US household uses about 10,500 kWh/year. A 5kW system producing 6,750 kWh/year offsets roughly 64% of that load. In a sunnier region like Arizona, 9,000 kWh covers about 86%. Actual offset depends on usage patterns, time-of-use rates, and whether you have battery storage.
Q: What's the difference between rated power and actual output on a 5kW system?
A: A 5kW system is rated at 5kW DC under Standard Test Conditions (STC) — 25°C cell temperature, 1,000 W/m² irradiance. Real-world conditions rarely match STC exactly. Performance ratio (the fraction of expected energy the system actually produces) for a well-functioning 5kW system typically runs 0.78–0.88. Below 0.75 indicates a problem. Above 0.88 with an older system is a strong signal the system is in good shape.
Data: pvlib physics modeling + Open-Meteo ERA5 weather data | Last updated: 2026-04-06 | Solar Benchmark