Solar Energy in Ontario, California

Above Average Solar Resource Pop. 175,265

Ontario, California receives 5.35 kWh/m²/day of solar irradiance and 6.1 peak sun hours daily, representing above-average solar resources . A typical 5 kW residential solar system in Ontario produces approximately 8,921 kWh annually, potentially saving homeowners $2,293 per year on electricity bills. After the 30% federal Investment Tax Credit, a 5 kW system has an estimated payback period of 4.6 years, leaving roughly 20 years of profitable operation within a standard 25-year warranty. For maximum annual output in Ontario, panels should be tilted at approximately 34° and oriented true south (180° azimuth).

Solar Resource Summary

5.35
kWh/m²/day
GHI Annual
6.1
hours/day
Peak Sun Hours
6.01
kWh/m²/day
DNI Annual
GHI vs. US national average (4.5 kWh/m²/day) Above Average
0 7.5 kWh/m²/day

Monthly Solar Data

Month JanFebMarAprMayJunJulAugSepOctNovDec Annual
GHI (kWh/m²/d) 3.06 3.64 5.11 6.12 6.9 7.48 7.79 7.22 5.96 4.49 3.5 2.86 5.35
DNI (kWh/m²/d) 4.6 4.43 5.61 6.17 6.32 7.15 7.92 7.64 6.78 5.56 5.25 4.6 6.01
Source: NREL. Monthly averages in kWh/m²/day and °C.

Solar Production Estimates for Ontario

5 kW Residential
Typical home system
Residential
8,921 kWh/yr
743 kWh/month avg
≈ $2,293/year savings
10 kW Residential
Large home system
Residential
17,841 kWh/yr
1,487 kWh/month avg
≈ $4,586/year savings
50 kW Commercial
Small commercial
Commercial
89,206 kWh/yr
7,434 kWh/month avg
100 kW Commercial
Medium commercial
Commercial
178,412 kWh/yr
14,868 kWh/month avg

Production estimates based on NREL solar resource data, 34° tilt, south-facing orientation, and 80% performance ratio.

Local Solar Conditions in Ontario

Ontario shows significant seasonal variation in solar output, with peak summer months receiving 7.8 kWh/m²/day compared to 2.9 kWh/m²/day in winter — a 2.7x difference. Battery storage or net metering is particularly valuable here.

Best Tilt Angle
34° (latitude-optimized)
Best Azimuth
180° (true south)
Coordinates
34.0633°N, -117.6509°

Financial Overview — Solar in Ontario

Solar is an excellent investment in Ontario. With a 4.6-year payback on a 5 kW system and 25-year panel warranties, early adopters in Ontario can expect 15+ years of net profit. Estimated annual savings from a 5 kW system: $2,293/year.

Avg. Electricity Rate
$0.257/kWh (CA avg)
Est. Annual Savings (5 kW)
$2,293/year
Est. Payback Period
4.6 years (after 30% ITC)
Federal ITC
30% of system cost
Net Metering
Available
Financial estimates assume a 5 kW system at $3,000/W installed ($15,000 pre-ITC, $10,500 after 30% credit). Actual costs vary by installer and equipment. Consult a local solar installer for firm quotes.

Solar FAQ — Ontario, California

In Ontario, California, a 5 kW residential solar system produces approximately 8,921 kWh of electricity per year. A 10 kW system produces about 17,841 kWh annually. These estimates use 5.3 kWh/m²/day average solar irradiance and an 80% system performance ratio, accounting for real-world losses from wiring, inverter efficiency, and temperature. Actual output will vary based on your specific roof orientation, shading, and equipment.

Ontario receives an average Global Horizontal Irradiance (GHI) of 5.35 kWh/m²/day. This is 0.85 kWh/m²/day above the US national average of 4.5 kWh/m²/day, placing Ontario above the national average. GHI measures total solar energy incident on a horizontal surface and is the primary indicator of a location's solar resource quality.

Ontario, California receives an average of 6.1 peak sun hours per day. Peak sun hours represent the equivalent number of hours when solar irradiance equals 1,000 W/m² — the standard condition used to rate solar panel output. This means a 1 kW solar panel array in Ontario produces 6.1 kWh on a typical day. Seasonal variation is significant: summer months see peak sun hours 40–60% higher than winter months in most US locations.

Ontario is a above average location for solar panels, with 5.35 kWh/m²/day solar irradiance — above the national average. With an estimated payback period of 4.6 years, solar installations in Ontario can be financially attractive, especially given California's electricity rates.

The optimal tilt angle for solar panels in Ontario is approximately 34°, which corresponds to the city's latitude. This angle maximizes annual energy production by ensuring panels receive the most direct sunlight averaged over the year. For maximum winter output, tilt panels at latitude + 15° (49°). For maximum summer output, use latitude − 15° (19°). Fixed south-facing panels at the latitude angle are the standard recommendation for residential systems in Ontario.

A 5 kW solar system in Ontario can save an estimated $2,293 per year on electricity bills, based on Ontario's average electricity rate of $0.257/kWh. Over a 25-year system lifetime, that represents $57,325 in total savings before accounting for electricity rate increases. After the 30% federal Investment Tax Credit, the net system cost of approximately $10,500 for a 5 kW system yields a payback period of 4.6 years.

For a typical home in Ontario using 1,000 kWh/month, a 5 kW solar system producing 743 kWh/month would offset approximately 74% of a typical household's electricity use. Most residential installations in similar climates range from 5 to 12 kW depending on energy consumption, roof size, and budget. Use SolarScope's Site Studio to get a personalized system size recommendation based on your specific address and energy bills.

Based on local solar irradiance and electricity rates, a 5 kW residential solar system in Ontario has an estimated payback period of 4.6 years. This calculation assumes a net system cost of $10,500 (after the 30% federal ITC) and annual savings of $2,293. Modern solar panels carry 25-year performance warranties, so systems in Ontario would operate profitably for roughly 20 years after payback. Electricity rate increases over time typically reduce the effective payback period.

Other Cities in California

Los Angeles
5.3 kWh/m²/d
San Diego
5.3 kWh/m²/d
San Jose
5.1 kWh/m²/d
San Francisco
5.0 kWh/m²/d
Sacramento
5.1 kWh/m²/d
Long Beach
5.2 kWh/m²/d
Bakersfield
5.4 kWh/m²/d
Fresno
5.3 kWh/m²/d
View all California solar data →
Learn more: Solar irradiance · Peak sun hours · GHI explained · Net metering · How solar analysis works

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This page shows area-level averages. For your specific address — accounting for roof orientation, shading trees, and your utility rate — use SolarScope's AI-powered Site Studio.

Open Site Studio Community Data for California

Quick Stats

Annual GHI
5.35 kWh/m²/day
Peak Sun Hours
6.1 h/day
5kW Production
8,921 kWh/yr
Payback (5kW)
4.6 years
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