Solar energy systems remain the best way for homeowners to save money on their electricity bills while reducing their home’s carbon footprint. They reduce homeowners’ dependence on utility companies and help shelter them from the effects of ever-rising electricity costs.
But solar energy systems aren’t one-size-fits-all. It’s crucial that your solar system design is optimized for ideal energy production. And new 2023 regulations make optimal sizing more important than ever for homeowners in California.Solar energy production isn't consistent throughout the year. There are fluctuations tied to the changing seasons.
Let’s discuss some of the factors surrounding solar’s seasonal productivity. We’ll focus on the northern hemisphere.
Sun position—Sunlight angles vary seasonally. In summer, the sun sits higher, providing more direct sunlight for maximum energy production. Conversely, the sun sits lower in the sky in winter, resulting in less direct sunlight and reduced energy production.
Daylight hours—Summer’s longer daylight hours give more time for your panels to absorb sunlight. This increases overall energy production compared to the shorter days of winter.
Seasonal shading—Ideally, sunlight’s path to your solar panels should not be obstructed by trees. If it is, there are seasonal factors to consider. Dense foliage in the summer can partially block sunlight and decrease energy production. Trees that lose their leaves in the fall will cast less shade during winter, improving energy production.
You might be surprised to learn that higher temperatures do not increase solar energy production. While other aspects of summertime conditions increase overall energy production, high heat can actually slightly reduce your solar system's efficiency.
The good news is that when high temperatures strike, you’ll enjoy your air-conditioned home with far lower utility bills and with far less impact on the environment.
Overall, solar panels are most productive in summertime conditions.
But the question remains: What season should I size my solar panels for?
A solar system sized for winter is larger than one sized for summer. This is because more panel wattage is needed to produce a given amount of energy in winter than in summer.
Note: You cannot significantly oversize your solar panel system relative to your past 12 months of energy usage without justification. California IOUs (Investor-Owned Utility Solar Photovoltaic (PV) Programs) can reject an interconnection application if the solar system is deemed too large.
A smaller solar system—one sized for summer—offers its own advantages and disadvantages.
California homeowners are impacted by Net Energy Metering (NEM) 3.0. Since April 15, 2023, this bill has dictated how excess solar energy is credited to homeowners.
The most notable impact is that the average export rate—the amount that energy companies pay homeowners for their excess solar energy production—was reduced from $0.30/kWh to $0.08/kWh.
Because the financial incentive for solar energy overproduction is now smaller, it’s often best to build a smaller (summer-sized) solar panel system.
Most prospective solar panel system owners should optimize to use all of the power generated by their solar panels and export little or no energy to the grid.
For systems without any solar batteries, payback is generally optimized when it is sized to produce 60–80% of the homeowner's past 12 months of electricity usage.
No, the changes do not impact homeowners who owned solar before April 2023 unless they increase their system size by 10% or 1kW (whichever is larger). Adding a solar battery also will not affect their NEM 1.0 or 2.0 lock-in status.
Speaking of batteries, solar batteries can greatly increase your ROI on solar—especially following the rollout of NEM 3.0.
Solar batteries (also known as solar energy storage or home batteries) are devices that store excess electricity generated by solar panels for later use. They can be installed outdoors or indoors, and are most often installed in garages.
Key benefits of solar batteries include…
Increased utility savings—Home batteries enable you to store excess energy produced during sun hours. You’ll then use that energy in the evenings when electricity pricing tends to be at its highest.
Protection from power outages—Your solar battery will detect a loss of grid power and switch to stored energy automatically, keeping your home powered.
Added insights—Your solar battery system can help you monitor your energy consumption. You can use these insights to make behavioral changes that further decrease your electricity bills.
Solar batteries capture and store the excess energy your solar panels generate rather than selling it back to the grid. Because NEM 3.0 makes selling energy to the grid less profitable, this is a huge advantage.
In other words, under NEM 3.0, it’s better to use the excess energy you generate rather than sell it to the grid. Solar batteries enable you to do this.
Whether you size for winter, summer, or somewhere in between, home batteries can drastically increase the return on your solar investment.
Clearly, there is much to consider when sizing a home solar system. Seasonal variations in productivity impact your ideal size. If you’re in California, you must also account for the impacts of NEM 3.0.
And there are even more factors that influence your solar system’s size: Your energy consumption, your goals, your home’s roof size and shape, and more.
But don’t be overwhelmed. Instead, leave it to the experts. A great solar team will ask you the right questions and design an optimized solar system for you and your family.
If you’re in California, we at Citadel are here to help you meet your savings and sustainability goals. For a free quote and answers to all your solar questions, get in touch with us.