Summer is when residential solar systems hit peak monthly production. If your system is undershooting expectations during May-August, something is usually wrong — and the warranty window for production guarantees and equipment defects is shorter than most homeowners realize. Here's what proper summer production looks like for typical residential systems in the seven states we cover.
Production basics — kWh per kW per day
Solar production scales with installed capacity (kW) and local solar resource. Industry-standard measurement: kWh per kW per day. A 1 kW system in central California produces about 5.0-5.5 kWh per day annual average, peaking around 7-8 kWh per day in June-July. Texas runs similar peaks; Florida slightly higher at 6-7 kWh per day in summer despite frequent afternoon thunderstorms (morning production is excellent). Northeast states (NY, NJ, MA, CT) summer peak around 5-6 kWh per kW per day.
Expected monthly production by state for an 8 kW system
For a representative 8 kW residential system installed properly with good roof orientation: California 1,400-1,700 kWh in June. Florida 1,300-1,500 kWh. Texas 1,400-1,600 kWh. New York 1,200-1,400 kWh. New Jersey 1,250-1,450 kWh. Massachusetts 1,200-1,400 kWh. Connecticut 1,150-1,350 kWh. If your June production is consistently below the low end of these ranges, investigate — you're losing money.
Common reasons summer production falls short
Soiling — bird droppings, pollen, dust accumulation. A clean rinse in early summer often recovers 5-10%. Shading — trees that have leafed out since installation, neighbor's new addition, even chimney shadows you didn't notice. Inverter issues — string inverters in extreme heat sometimes throttle output; microinverters or optimizers are more resilient. Module degradation — quality Tier-1 panels degrade about 0.5% per year, so an 8-year-old system should produce 96% of original output, not 80%. Significant year-over-year drop suggests panel-level failure worth a warranty claim.
How to actually measure your production
Don't rely on monthly utility bills as the only production metric — net metering masks system performance. Use your inverter's monitoring app (Enphase Enlighten, SolarEdge mySolarEdge, Generac PWRview) for daily production data. Compare current month to prior years in the same month. Significant deviation (more than 5-10%) warrants investigation. Tools like PVWatts (free, NREL) let you compare your actual vs. predicted production for your exact location.
Warranty and production guarantee timing
If your installer offered a production guarantee, file warranty claims promptly when you see persistent underperformance. Most installer production guarantees expire 1-5 years after activation. Manufacturer panel warranties (typically 25-year linear performance) require documentation and often a third-party inspection. Don't wait until year 10 to file a claim that should've been filed in year 2.
Compare local quotes from licensed pros
The Home Service Guide pre-vets every contractor in our network for licensing, insurance, and complaint history.
Get my free quotes →Frequently Asked Questions
How much should my solar system produce in summer?
For a typical 8 kW residential system installed properly: California 1,400-1,700 kWh in June; Florida 1,300-1,500 kWh; Texas 1,400-1,600 kWh; Northeast states (NY, NJ, MA, CT) 1,150-1,450 kWh. Significant underperformance vs these ranges warrants investigation.
Why is my solar production lower this year?
Common causes: panel soiling (bird droppings, pollen, dust), new shading from tree growth or neighbor additions, inverter throttling in heat, or actual panel degradation. Check your monitoring app for daily production data and compare to prior years.
Should I clean my solar panels in summer?
For most climates, rainfall handles routine cleaning. A spring rinse with a soft brush and water (no chemicals) often recovers 5-10% production if there's visible soiling. Heavy bird-droppings concentrations on panels under perches warrant manual cleaning. Never use abrasive cleaners.
Is my solar warranty still valid in 2026?
Manufacturer warranties on quality Tier-1 panels typically run 25 years on production. Installer workmanship warranties typically run 10 years on labor. Production guarantees (where offered) typically expire 1-5 years after activation. File warranty claims as soon as you identify a problem — most warranties require prompt notification.