Buying an inverter? Make sure it’s battery-ready

If your inverter isn’t battery-ready, it’s already outdated.

By Jeremy Niles, marketing manager at Pika Energy. Originally posted on Pika Energy’s blog.

Imagine this: You are a homeowner who spent $20,000 on a grid-tied solar energy system five years ago. Since then, your solar array has worked flawlessly, producing power during the day to offset your energy consumption in the evenings.

Your utility just announced that it is introducing a time-of-use rate schedule, where the energy you produce during the day is worth roughly half what the energy you use in the evening costs. You realize that by selling energy back to the grid during those peak rate periods, you can access a better rate of return on your system than originally forecasted by your installer.

Furthermore, a battery would be a silent and maintenance-free alternative to the backup generator you may have been considering. The only issue is, you don’t have a battery-ready inverter so your options are limited. Any “AC-coupled” battery option will be inefficient, and most of the available options are underpowered and slow to back up loads, making them ineffective backup solutions.

Now your neighbor is considering adding solar to their home. What is your advice? Tell them to buy a battery-ready solar inverter.

A brief history of buying home solar

Not long ago, choosing the make and model of a solar panel was the most important decision that affected the performance of a home solar system. That is no longer the case. Not only are solar modules more powerful, efficient, and cost-effective than ever before, making the choice less impactful, but the ways that we derive value from our solar systems are changing rapidly.

The decision is now about far more than just solar modules; it’s about the entire system and how it integrates solar and storage with the grid and your home.

Many utilities are introducing programs that erode or destroy the value of traditional net-metered solar energy, while others are introducing incentives that increase the value of “smart” solar.

In either case, a smart battery-ready inverter is an adaptable system that will maintain or even improve the value of your solar system over its operational lifetime–even if you don’t decide to add a battery right away. Enter the age of smart solar+storage systems like the Pika Energy Island.

Why do we need battery-ready inverters?

Extreme weather and shifting utility price structures are changing our needs as electricity consumers. Utilities are increasing energy prices and introducing rate structures (known as time-of-use or TOU) that adjust your rate by the hour. Some are even prohibiting the connection of residential solar systems to the grid or refusing to pay for excess solar energy that is sent to the grid. Even if you have energy security today, you may not tomorrow.

A residential solar system is typically warrantied for 10, 20 or even 25 years with an expected functional lifetime that goes far beyond that time period. The odds that your utility will change its rate structure or solar feed-in policy, or that you will experience power outages due to extreme weather, are increasing all the time.

With that in mind, it’s important for solar buyers to understand that a standard grid-tied system does not provide power when utility power is out and cannot adjust to new utility billing structures. Installing a battery-ready solar inverter is the best way for solar buyers to insulate themselves from future risk and prepare for the addition of an energy storage system when they need one.

What to look for in an inverter

  1. Flexibility: If your solar installer does their job right, part of their pitch to you will be a survey of your plans for future growth. They will want to give you the option of buying a larger system that will be sufficient to meet your energy needs when you add a family member, start driving an electric vehicle or install a heat pump. Rather than buying more than you need today, consider buying an inverter that will let you upgrade and expand your array and battery system in the future.
  2. Battery compatibility out of the box: Generic AC-coupled batteries boast the ability to be connected to any inverter, even ones that are not “battery-ready.” However, this “jack-of-all-trades” functionality comes at the cost of efficiency, power and elegance.
  3. Efficiency: Solar panels are more efficient than ever. In the 40 years of industry R&D between 1974 and 2014, the best silicon solar cells (the type used in home solar) doubled in efficiency, going from 10% to 20% efficient. To the homeowner, these technological gains may represent hundreds of additional megawatt-hours of solar production and thousands of dollars of value over the lifetime of a solar system. These gains are seriously diminished if you install an AC-coupled solar+storage system that can waste twice as much (14% or more) energy as a DC-coupled, battery-ready solar inverter (9% or less).
  4. Smart grid compatibility: Today, few homes are connected to smart grid or demand response systems; but more of these networks are cropping up every day, and soon they will be the norm. Smart grids can give kickbacks in the form of cash or credit to the owners of distributed energy resources (like solar systems, battery systems and even electric vehicles) who help to make the grid more efficient by allowing their assets to supply or absorb grid energy. Having an inverter that is “smart grid ready” like the Pika Islanding Inverter is paramount.

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