Solar panels in El Cajon: what they cost and what they make
A typical El Cajon home needs 9 solar panels. They would make about 6,497 kWh a year and cost $9,500 to $14k before incentives. At today's electricity prices they pay for themselves in about 9.0 yrs.
See panels on your own El Cajon roof
Type your address. You get your roof from above, the panels that fit, a month-by-month forecast and a battery test. No phone number.
What solar costs in El Cajon
At $3.00 a watt, the median price cash buyers pay nationally, a 3.8 kW system costs about $11,400. Quotes in El Cajon will usually fall between $9,500 and $14,250. Complex roofs, main-panel upgrades and financing push prices up.
The 30% federal tax credit no longer applies to systems homeowners buy. This estimate includes no state or utility incentives; check with your utility before you buy.
The number that decides whether solar pays in El Cajon is what your utility pays for the power you send back. California’s Net Billing Tariff (since Apr 15, 2023) credits exports at Avoided Cost Calculator values, locked for 9 years per vintage. Under full payback is about 5.3 yrs. Under net billing it is about 9.0 yrs, because only the ~40% of solar a typical home uses as it is made saves the full retail price.
Cash purchase, prices rising 2.5% a year, panels losing 0.5% a year, $25/kW a year for upkeep. No federal credit for homeowner-owned systems.
Every way to pay for a 3.8 kW system in El Cajon
Change any number →| Way to pay | Day one | Monthly payment | Monthly net, year 1 | Ahead after 25 years |
|---|---|---|---|---|
| Pay cash Full price on install day | $11,400 | $0 | +$96 | $26k |
| Credit-union loan 8% APR, 20 years, no dealer fee | $0 | $95 | +$1 | $15k |
| “1.99%” solar loan 1.99% APR, 25 years, 25% dealer fee | $0 | $60 | +$36 | $20k |
| Lease $90/mo, +2.9%/yr | $0 | $90 | +$14 | $1,200 |
| Power purchase (PPA) 16.4¢/kWh, +2.9%/yr | $0 | $89 | +$16 | $4,200 |
Under net billing, the usual rule for new customers here, at 33.3¢/kWh rising 2.5% a year. The “1.99%” loan’s $2,850 dealer fee is included in its payments. Lease and PPA prices are typical offers, not quotes.
How much sunshine El Cajon gets
kWh per kW, 25° southMay is the best month for solar in El Cajon, and Dec the weakest: a Dec day makes 70% of a May day. A 6 kW system would make about 678 kWh in Dec and 968 kWh in May.
On June 21 the sun rises at 5:40 am and sets at 7:59 pm, 14 hours 19 minutes of daylight. On December 21 it is up from 6:46 am to 4:45 pm, just 9 hours 59 minutes.
Peak sun hours in El Cajon, month by month
| Month | Flat ground | Panels at 31° | kWh per kW |
|---|---|---|---|
| Jan | 3.4 | 5.3 | 122 |
| Feb | 4.2 | 5.8 | 122 |
| Mar | 5.5 | 6.6 | 156 |
| Apr | 6.6 | 6.8 | 161 |
| May | 7.1 | 6.6 | 161 |
| Jun | 7.4 | 6.5 | 153 |
| Jul | 7.2 | 6.4 | 155 |
| Aug | 6.9 | 6.7 | 159 |
| Sep | 5.9 | 6.7 | 150 |
| Oct | 4.7 | 6.3 | 144 |
| Nov | 3.6 | 5.6 | 123 |
| Dec | 3.0 | 4.9 | 113 |
| Year | 5.5 | 6.2 | 1,719 |
A peak sun hour is one hour of sunlight at 1,000 W per m². Why sites disagree.
The best angle and direction for panels in El Cajon
| Roof faces (6/12 pitch) | Output vs south | kWh per kW |
|---|---|---|
| South | 100% | 1,719 |
| Southeast | 96% | 1,650 |
| Southwest | 96% | 1,650 |
| East | 84% | 1,444 |
| West | 84% | 1,444 |
| North | 63% | 1,083 |
Face panels south and tilt them 31° for the most energy over a year. East and west roofs keep about 84% of that. A north-facing roof keeps 63%, which is rarely worth the money. Try other angles.
Where the sun goes over El Cajon
The noon sun is lower in winter, which is why the best winter tilt (57°) is steeper than the best summer tilt (4°).
El Cajon's homes
El Cajon has 33,890 households. 41.5% own their home, and 11,914 of those owners live in single-family houses, the kind of home that usually gets rooftop solar.
The median home here was built in 1974. Many roofs that age are due for replacement. Replace the roof first, then add solar: taking panels off and putting them back later costs thousands.
43.7% of homes heat with electricity and 47.1% with gas. If you switch to a heat pump or an electric car, plan for more panels or leave room on the roof.
Source: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates.
If the power goes out in El Cajon
Solar panels alone shut off in a blackout. Add a battery and they keep going. One Tesla Powerwall 3 (13.5 kWh) running a fridge, freezer, furnace fan, lights, Wi-Fi, TV and microwave (6.9 kWh a day):
Change the appliances, the battery and the weather in the battery calculator.
Questions people ask about solar in El Cajon
How much do solar panels cost in El Cajon?
A 3.8 kW system — enough for the average California home — costs about $9,500 to $14,250 before incentives, based on $2.50–$3.75 per watt. The 30% federal credit no longer applies to systems homeowners buy.
How many solar panels does a house in El Cajon need?
About 9 panels of 420 watts for a home using 503 kWh a month, the California average. Each kilowatt of panels here makes about 1,719 kWh a year on a south-facing roof.
Is solar worth it in El Cajon?
Over 25 years, solar power here costs about 9.0¢ per kWh, against 33.3¢ from the grid today. Payback is about 5.3 yrs if your utility credits exported power at the full retail rate, and 9.0 yrs if it pays about 30% of retail. Most new customers in California are on the lower rate.
How many peak sun hours does El Cajon get?
6.2 a day on panels tilted to 31°, and 5.5 on flat ground. The best month is Apr; the weakest is Dec.
What is the best angle for solar panels in El Cajon?
31° for the most energy over a year, facing south. 57° is best in winter and 4° in summer. On a normal pitched roof, anything within 15° of 31° gives you about 95% of the maximum.
How long would a home battery last in a El Cajon power outage?
A Tesla Powerwall 3 running a fridge, freezer, furnace fan, lights, Wi-Fi, TV and microwave (6.9 kWh a day) lasts about 43 hours with no sun. With 7 kW of solar to recharge it, it gets through a three-day outage even in overcast January.
Solar near El Cajon
| City | Miles | kWh per kW | Sun hours |
|---|---|---|---|
| Santee, CA | 4 | 1,725 | 6.2 |
| La Mesa, CA | 4 | 1,712 | 6.1 |
| San Diego, CA | 10 | 1,698 | 6.1 |
| National City, CA | 12 | 1,689 | 6.0 |
| Chula Vista, CA | 12 | 1,704 | 6.1 |
El Cajon shares a weather-data neighbourhood with San Diego; their sunshine numbers differ by less than our data can resolve. Housing, prices and outage figures are specific to El Cajon.
Cities with the same sunshine as El Cajon
These far-away cities get almost exactly as much solar energy per panel.
- Amarillo, TX 1,725 kWh per kW
- Pueblo, CO 1,723 kWh per kW
- Lubbock, TX 1,731 kWh per kW
Sources: NASA POWER 2001–2020 monthly climatology (grid cell 55 km from El Cajon's Census point), our PV model (within 1.6% of NLR PVWatts® on average), U.S. EIA prices and use, U.S. Census 2025 population estimates and ACS 2020–2024. Estimates for an average home, not a site survey. How we calculate.