Combine the Power of Generators and Batteries with Your Solar System

While the utility grids are fairly reliable in most urban neighborhoods, in many rural areas long outages are not uncommon. If you want the peace of mind to have power, even when the grid is down, it makes sense to add a generator, a battery, or both to your solar system.

Generators have been the standby option for years, and battery storage now is a viable alternative to add if a homeowner has solar.

Why? Most solar power systems are grid-tied, and do not allow power to be used or produced when the grid is down (protects the utility lineman from the power that could back-feed the grid from a solar system).

And by adding a battery storage solution to the solar, you can use the solar power during the day, and store it to the battery to be used at night. Taking it even one step further, during long storms when there is not very much solar access, a small generator can be used to charge batteries. Why do people add battery storage?

  1. For convenience purposes.
  2. To keep your refrigerator and freezer humming while you’re away in the event of a power outage (don’t return from vacation to rotting groceries in the fridge).
  3. To run your well 24/7.
  4. To charge a laptop, cell phone, or keep the router working.
  5. To operate medical equipment.
  6. To keep your electrical fence operative to secure livestock.
  7. To open a garage door or electric gate.
  8. To charge an electric car.

The Importance of a Backup System

Having a backup for your solar power system is becoming a requirement for some and a primary reason for going solar for others.

Heavy wind and rain, falling tree limbs, fires like we experienced in October, and earthquakes are among the many things that can still cause the grid to fail for extended periods of time. Also as Sonoma County rebuilds, frequent outages will occur as new homes are under construction.

The grid we have is a throwback to 1935, an approach of producing power in large power plants and transmitting it over long distances to homes and businesses. As more power is needed, more or larger wires, transformers, and other equipment are added.

It is the hope of many that we will learn from recent events how non-resilient this older grid is, and move to a more distributed grid, which incorporates just what we are discussing here, solar and storage.

Let’s discuss the options.

Advantages and Disadvantages of Generators and Batteries

A backup generator has been the go-to for many years to back up in a disaster and can use some different types of fuel such as natural gas, gasoline, diesel, or propane. Here are some benefits to generators:

  1. They have on-demand energy and aren’t weather dependent.
  2. They cost less than batteries.
  3. They handle high loads.
  4. They are easier to size than batteries.

There are also some disadvantages to generators:

  1. Fuel storage.
  2. The run whether you have on an alarm clock or well pump, which can be a waste of energy.
  3. They can be noisy.
  4. They require maintenance.
  5. There can be homeowner association regulations, and zoning and permitting issues.
  6. They cannot interact with the grid (“peak shave”).

There are also benefits and disadvantages to batteries. Here are some of the benefits:

  1. They are quiet.
  2. They are chargeable from the sun.
  3. You can meet long-term disaster planning, charging from the sun.
  4. They are interactive with the grid (“peak shave”).

Disadvantages to batteries:

  1. They’re not good for heavy loads.
  2. They have a limited amount of power.
  3. Sizing is more critical.
  4. They are weather dependent.
  5. Batteries can be expensive.

The Advantages of Generators with Batteries

Many customers are also installing batteries with generators. This option allows the sizing of smaller storage. When batteries are combined with generators, there are several benefits. Namely when the weather is poor or in the evening, when the storage system gets to 10% battery, the generator automatically turns on and uses all of its power to recharge the battery, and then turns off. This makes for a truly redundant system.

In the past, many chose to install generators because they were about 50% of the cost of buying a storage system. Also, storage systems were unsightly, with rows of lead acid batteries to deal with.

Current systems like Sonnen batteries eliminate these disadvantages. While they can be twice the cost of a generator, they can also store energy when power is less expensive, which you can use when power companies charge more for energy usage. Known as “peak shaving,” this practice saves people money every day.

Also, lithium ion batteries have a clean, modern look and require minimal upkeep. Why did we choose Sonnen as our storage solution for customers needing backup?

Sonnen batteries:

  1. Are completely integrated.
  2. Have one of the largest outputs of power (important for pumps and heavy loads).
  3. Are safe and reliable.
  4. Have a proven technology with 20,000 installed users.

We mentioned peak shaving a few times in this blog post. Stay tuned for our next blog post will go into more detail about the benefits of “peak shaving,” also known as self-consumption.