solar system

During the day when the sun is high in the sky, your solar system hums right along, often producing more power than you use.

Your well works, the toaster pops up freshly sliced ciabatta, and you can drink a hot cup of tea or coffee throughout the morning and afternoon.

What Is Your Energy Source After the Sun Sets?

But all that changes at night after the sun sets below the horizon and the moon rises. When you use more power then your grid-tied solar system produces, you buy power from your utility.

Most of us don’t know where this energy comes from. Is it from nuclear or fossil fuel, power plant source or from renewable resources?

Solar, by itself, is also suffering from its success. Peak rates, those most expensive to customers, used to be from noon to 6 pm.

Solar produces a lot of power during these daylight hours, covering the peak usage of solar customers and often allowing them to “export” excess power at these high rates.

Since rates were lower in the evening, this was a real win-win for solar customers, selling energy when costs were high and buying when fees were low.

Due to the success of solar adding so much power to the middle of the day and early evening, these peak times are now shifting into the late afternoon and evening when solar power is waning, lowering the benefit of solar power.

Also, the utilities are now charging an export fee ($.022 per kWh at the time of this Blog) for all power exported, further reducing the benefit previous solar users have enjoyed. In most cases, solar is still easy to justify since utility rates continue to increase while the cost of solar is still slightly declining.

So where does storage come in?

Add Storage to Your Solar System with Batteries Capable of Peak Shaving

With storage, you can collect energy from the sun during the day, store it, and power your home or business at night when rates are higher. Storing energy and using it later is also known as self-consumption or more technically as peak shaving.

As we mentioned in the previous blog post, peak shaving is used to reduce your electrical power consumption with companies like PG&E during periods of maximum demand when the cost of electricity is higher.

So when the cost of energy peaks, you “shave” energy from your battery storage system. Peak shaving is one reason to purchase a battery. Also in most cases, if the storage system is charged from the solar system, the user receives the same federal tax credit as solar (30% at the time of writing this blog post).

One other benefit of storage is when energy is stored locally in batteries it eliminates the utility’s solar export charges.

Storage systems used to peak shave, or self-consume may or may not also be used for energy storage when the power is out. One of the systems we install is Enphase Energy’s AC Storage, which is a great peak shaving (self-consumption) system.

It works every day to store energy when rates are low, and discharge energy when rates are expensive. Usually, these systems can be justified on the peak shaving benefit and have a lower cost to then back-up systems since they eliminate the cost of installing automated disconnects and load centers.

These types of systems work great in urban areas where energy from the utility is more reliable.

The Sonnen Option

In the past, generators were the backup of choice for customers needing power when the utility was down since they cost about half as much as storage systems. This has changed with the Sonnen system we sell, providing both backup and self-consumption. Storage systems can now provide better long-term value than generators (see blog post about combining the power of generators and batteries with your solar system).

By adding self consumption to backup systems, Storage can also serve a dual purpose by providing a positive financial justification that straight back-up systems never had. Many of our customers set the controls to allow their batteries to self-consume to say 50%, saving money daily and saving a reserve for backup should the power go out in the evening.

So if you have a solar system without storage, maybe it’s time to take a look and see whether the financial benefits of a battery would provide the peace of mind you’re looking for.