Does Solar Still Pay Off in an El Niño Winter? Rain, Clouds and Winter Production in San Diego

NOAA expects a strong El Niño this winter, and that usually tilts Southern California toward a wetter season. Here’s what a rainy winter actually does to a San Diego solar system, and why it doesn’t break the math.

https://www.youtube.com/watch?v=FKxe6dZE50s

Key takeaways

• NOAA’s Climate Prediction Center says El Niño continues to strengthen, with a strong-to-very strong event likely through January to March 2027, and NOAA’s winter outlook favors wetter-than-average conditions from California to Florida.
• A wetter winter isn’t guaranteed. The National Weather Service in San Diego notes that the strong El Niño of 2015-16 was drier than normal in Southern California.
• Winter is already the low season for solar. In the federal PVWatts model, a San Diego system produces about 103 to 107 kWh per kW in December through February, versus about 158 to 160 in July and August.
• Panels keep producing on cloudy and rainy days from diffuse light, just at reduced output. Production estimates are built on a typical year of weather, so wet and dry years average out.
• SDG&E bills solar on an annual true-up, so spring and summer production carries the winter months. A battery adds backup for storm outages.

Frequently asked questions

Do solar panels work in the rain?

Yes, at reduced output. Thick clouds block direct sunlight, but panels still produce from the diffuse light that gets through. Output picks back up as soon as a storm clears.

How much less do solar panels produce in winter in San Diego?

In the federal PVWatts model, a 1 kW south-facing system in San Diego produces about 103 to 107 kWh a month from December through February, roughly two-thirds of a July or August month. The three winter months together are about 20 percent of the year’s production.

Will El Niño affect my solar savings?

Somewhat, but less than you might think. Winter is already a small share of the year’s production. As an illustration, if December through February came in 20 percent below normal, annual production would fall by about 4 percent, and the rest of the year is unaffected.

Is a strong El Niño coming this winter?

NOAA’s Climate Prediction Center said in October 2026 that El Niño continues to strengthen, with a strong-to-very strong El Niño likely through January to March 2027. Its next update is due November 12, 2026.

Should I wait until spring to go solar?

There’s no production reason to wait. A system that turns on in winter starts producing right away, and the long days of spring and summer build up credits under SDG&E’s annual true-up. If storm outages worry you, a battery installed before the wettest months adds backup.

---

Stellar Solar has been talking about El Niño a lot this fall, and for good reason: NOAA expects a strong one. A strong El Niño often means more storms for Southern California, and a natural question follows. If it rains all winter, do solar panels still pay off?

They do. Here’s why, with the numbers.

What NOAA is forecasting

NOAA’s Climate Prediction Center publishes its ENSO outlook monthly. Its October 2026 discussion kept an El Niño Advisory in effect and said El Niño continues to strengthen, with a strong-to-very strong El Niño likely through January to March 2027. The next update is due November 12.

NOAA’s winter outlook, released October 15, says wetter-than-average conditions are likely across the southern U.S., from California to Florida.

What El Niño has meant for San Diego

El Niño tilts the odds toward a wet Southern California winter, but it doesn’t guarantee one. The three strongest El Niños on record before this one show the range. Rainfall at San Diego’s Lindbergh Field, measured over each October-to-September water year by the San Diego County Water Authority, came in at:

Water year	Lindbergh Field rainfall
1982-83	18.49 inches
1997-98	17.16 inches
2015-16	8.18 inches

San Diego’s normal is about 10 inches a year. The National Weather Service in San Diego points out that 2015-16 was drier than normal here despite a strong El Niño. So a very wet winter is possible this year, but not certain.

Winter is already the low season

Solar panels produce less in winter in every year, wet or dry. Days are shorter and the sun sits lower in the sky. The federal PVWatts calculator estimates that a 1 kW south-facing system in San Diego produces:

Month	Production
December	103 kWh
January	107 kWh
February	107 kWh
July	158 kWh
August	160 kWh
Full year	about 1,600 kWh

The three winter months together are about 20 percent of the year. Even in winter, a San Diego month produces roughly two-thirds of a summer month.

What clouds and rain do

On a stormy day, thick clouds block the direct beam of sunlight, as the U.S. Department of Energy explains, and on a clear day that direct beam is most of the energy panels capture. What’s left is diffuse light scattered through the clouds, and panels keep producing from it at a fraction of their clear-day output. Storms in San Diego also come in waves, and production rebounds on the clear days in between.

The important part: the production estimate you get from an installer is already built on a typical year of weather. PVWatts uses a “typical meteorological year” assembled from many years of data, so it includes rainy winters and dry ones.

Why a wet winter barely moves the annual number

Here’s a simple illustration. Suppose El Niño storms cut December through February production 20 percent below normal. Those three months are about 20 percent of the year, so the hit to annual production is about 4 percent. The other nine months are unaffected.

And SDG&E’s billing is designed for this. Both NEM 2.0 and the Solar Billing Plan settle on an annual true-up. Under the Solar Billing Plan, export credits roll over from month to month until they’re used, so credits earned in sunny spring and summer months help cover the winter. We walk through how the plans compare in SDG&E net metering in 2026.

The real El Niño risk is outages

Big winter storms bring wind, falling trees and downed lines, and that means power outages. Grid-tied solar shuts off when the grid does, by design, so panels alone won’t keep the lights on during a storm. We explain why in does solar work when the power goes out?

A battery is the piece that turns solar into backup. It carries the house through the outage, and on the clear days between storms the panels recharge it. If you’re weighing a battery against a generator for storm season, see solar plus battery vs. a generator.

Get ready before the storms

A wet winter won’t undo the savings from solar, but it’s a good reason to add backup. Stellar Solar can show you a production estimate for your roof, month by month, and design a battery system that keeps your home running through storm outages. Stellar Solar has been San Diego’s trusted solar installer since 1998, A+ rated with the BBB and a repeat winner of San Diego’s Best Solar in the Union-Tribune Readers Poll. Call 866.787.6527 for a free evaluation, or get your free quote here.

from Stellar Solar https://ift.tt/Fk46oMY

Going Solar in Inland San Diego County: Escondido, San Marcos, Vista, Ramona and El Cajon

A few miles from the beach, the weather changes, and so does the solar math. Inland homes get more sun, run more air conditioning and face more fire weather, and a system designed for the coast won’t fit them.

https://www.youtube.com/watch?v=u86Zob-S-hk

Key takeaways

• Inland San Diego County is much hotter in summer. In August 2023, average highs were about 77°F at San Diego’s airport, about 90°F in Escondido and about 92°F in Ramona, according to the National Weather Service.
• Inland roofs also get more sun. In the federal PVWatts model, a south-facing system in Escondido produces about 6 percent more per year than the same system near downtown San Diego, with the biggest gains in May and June.
• Heat trims panel output, typically about 0.26 to 0.40 percent for every degree Celsius above 25°C (77°F) for modern panels, so panel choice and airflow matter more inland.
• Bigger air conditioning loads land in SDG&E’s 4 to 9 p.m. peak, so inland homes get more value from west-facing panels and a battery.
• Backcountry areas around Ramona, Alpine and Jamul face more fire weather and power shutoffs, which makes backup power part of the design.

Frequently asked questions

Does solar produce more inland than on the coast in San Diego?

Usually, yes. In the federal PVWatts model, a 1 kW south-facing system produces about 1,700 kWh a year in Escondido versus about 1,600 kWh near downtown San Diego. Inland areas tend to clear the marine layer sooner, which shows up most in May and June.

Do solar panels lose efficiency in the heat?

Yes, a little. Modern panels typically lose about 0.26 to 0.40 percent of output per degree Celsius above 25°C, and a panel on a hot roof runs well above the air temperature. Inland homes still come out ahead on annual production, but panels with a low temperature coefficient are worth a look.

What is SDG&E’s Inland climate zone?

SDG&E divides its territory into Coastal, Inland, Mountain and Desert baseline zones. The baseline allowance, the amount of electricity SDG&E treats as a basic need, is a little higher in the Inland zone in summer: 10.4 kWh per day versus 9.0 on the coast under SDG&E’s Schedule DR.

How big should a solar system be for a hot inland home?

Size it to a full year of your actual usage, not a rule of thumb. Inland homes often use far more electricity in summer for air conditioning, and much of that falls in SDG&E’s 4 to 9 p.m. peak, which is why many inland designs add west-facing panels or a battery.

Do I need a battery in Ramona or East County?

It depends on your goals, but inland homes have two extra reasons to consider one: evening air conditioning during the most expensive hours, and power shutoffs during fire weather, which hit backcountry communities more often than the coast.

---

San Diego County has two climates, and anyone who drives from Carlsbad to Escondido in August knows it. The coast stays mild under the marine layer. Inland North County and East County bake. That difference shows up in your electric bill, and it should show up in your solar design.

Here’s what changes when your home is in Escondido, San Marcos, Vista, Ramona, El Cajon, La Mesa, Spring Valley or anywhere else east of the coastal strip.

Inland summers run hotter

The National Weather Service’s monthly climate summary for August 2023 shows the gap: the average high was about 77°F at San Diego’s airport, about 90°F in Escondido and about 92°F in Ramona. El Cajon and the East County valleys run hot for the same reason. They’re far enough from the ocean that sea breezes don’t cool them down.

More heat means more air conditioning, and air conditioning is usually the biggest summer load in an inland home. We break down how much of that solar can cover in how much of your summer AC can solar offset?

Inland roofs get more sun

The good news is that the same distance from the coast that brings the heat also brings more sunshine. Coastal neighborhoods spend many late-spring and early-summer mornings under May Gray and June Gloom. Inland, that cloud deck usually burns off sooner.

You can see it in the federal PVWatts calculator. For a 1 kW south-facing system with standard assumptions, PVWatts estimates:

Location	May	June	Annual
Downtown San Diego	143 kWh	147 kWh	about 1,600 kWh
Escondido	163 kWh	161 kWh	about 1,700 kWh

That’s about 6 percent more energy per year from the same panels, already accounting for the heat.

Heat costs a little output

Solar panels are rated at 25°C (77°F), and they get slightly less efficient as they warm up. The measure is the temperature coefficient: modern panels typically lose about 0.26 to 0.40 percent of output for every degree Celsius above 25°C. A panel on a dark roof on an inland August afternoon can run 30°C or more above that rating, which can mean roughly 10 percent less output in the hottest hours.

You can’t change the weather, but you can design around it:

• Choose panels with a low temperature coefficient. Many premium panels are rated around 0.26 to 0.30 percent per degree.
• Leave airflow under the array. Standard racking keeps panels off the roof surface so they shed heat.
• Don’t oversize to compensate for heat. The production estimate already accounts for it, so size to your usage.

The bill is shaped by the evening

SDG&E’s most expensive hours are 4 to 9 p.m., every day of the year. On a hot inland afternoon, that’s exactly when the house is hottest and the air conditioner works hardest. Under the Solar Billing Plan, solar you export at midday earns far less than the power you buy back in the evening, so the inland design question is how to cover those hours.

Two tools do most of the work:

• West-facing panels shift production later into the afternoon. We explain the tradeoff in why west-facing solar beats south in San Diego.
• A battery stores midday solar and runs the house through the evening peak.

Your baseline zone

SDG&E divides its territory into four baseline climate zones: Coastal, Inland, Mountain and Desert. Your zone sets your baseline allowance, the amount of electricity SDG&E treats as a basic need. Under SDG&E’s Schedule DR, the summer baseline is 10.4 kWh per day in the Inland zone versus 9.0 on the coast. Most inland homes blow well past either number on a hot day, so the zone matters less than the air conditioner. Higher-elevation areas can fall in a different zone, and SDG&E’s baseline tools show which applies to your address.

Fire weather and power shutoffs

The backcountry around Ramona, Alpine and Jamul sits close to wildland, and SDG&E is more likely to shut off power there during Santa Ana wind events. If you live east of the I-15, it’s worth checking your address against the state’s fire-threat map, which we walk through in do you live in an SDG&E High Fire Threat District?

Grid-tied solar shuts off during an outage, so backup takes a battery. For larger inland homes with pools, well pumps or medical equipment, it’s worth deciding up front which circuits need to stay on.

A few city notes

• Escondido and San Marcos. Hot summers, plenty of sun, and many homes with pools and big air conditioning loads. Strong candidates for west-facing panels and a battery.
• Vista. Sits between the coast and the inland valleys, so summer temperatures fall in between. Production estimates should use your actual address, not a coastal or inland average.
• Ramona. Higher elevation, hot summers, cold nights and larger lots. Ground-mount solar is sometimes an option, and backup deserves extra attention.
• El Cajon, La Mesa and Spring Valley. East County valley heat makes the evening peak the main design challenge.

Design for where you live

An inland home isn’t a coastal home with a bigger air conditioner. It has more sun, more heat, a later peak and, in some areas, more shutoff risk. Stellar Solar designs around all four, using your address and a full year of your usage. Stellar Solar has been San Diego’s trusted solar installer since 1998, A+ rated with the BBB and a repeat winner of San Diego’s Best Solar in the Union-Tribune Readers Poll. Call 866.787.6527 for a free evaluation, or get your free quote here.

from Stellar Solar https://ift.tt/qdKivVt