Blog Post

CTO Technical Q&A: Pairing Energy Storage with Microinverters

Stuart Lennox - CTO

Stuart Lennox – CTO

As solar microinverters have grown in popularity, we’ve noticed a few common questions popping up from our customer base about microinverters and energy storage. So we took a minute with our founder and CTO Stuart Lennox to get the download on how microinverters and SimpliPhi’s energy storage solution play well with each other.

How do energy storage solutions and microinverters pair together?

The benefit of residential microinverters is that power conversion from direct current (DC) to alternating current (AC) used by the home happens at the individual solar panel level. This panel-level conversion allows for the solar system to compensate more readily for variances in the level of sun the panel is exposed to, creating a more resilient system where each panel’s performance does not affect another’s as it would with a non-optimized string inverter-based system.

Regardless of if you are using microinverters or not, you will always need a device to charge the batteries. For DC power, this would be a charge controller that then feeds DC power to a traditional inverter, which converts the DC to AC. For AC power coming from the microinverters, an inverter charger can be used instead. An inverter charger converts the AC current back to DC for charging, then feeds the power to a traditional inverter to convert the (now) DC power back to AC for use in the building.

What advantages are there for AC coupling microinverters and batteries?

Basically, when you are connecting microinverters to a battery-based inverter, you create a micro-grid. This is generally referred to as AC coupling because the microinverters and the battery-based inverters are “coupled” on their AC outputs. Such systems have advantages over traditional grid tied systems, as they can provide power
during outages, in emergency situations and to remote off-grid locations.

AC coupling allows you to take advantage of all the benefits of microinverters, such as greater design flexibility, increased safety and increased performance that come with module-level maximum power point tracking (MPPT) and monitoring.

What safety considerations should people keep in mind when AC coupling microinverters and battery solutions?

Any energy storage solution is going to be more complicated than a solar solution that feeds energy directly into the utility grid. Installers and designers must be qualified experts before working with battery-based systems and AC coupled systems. While we do not have time to go into all the qualifications required, we can provide some guidelines.

Be careful not to overcharge the batteries. Even with SimpliPhi’s combination of lithium iron phosphate chemistry, a highly innovative battery architecture and battery management system that does not generate heat or require cooling, overcharging is not recommended. If you are using other batteries besides those from SimpliPhi, the dangers of overheating and thermal runaway is even more risky from overcharging.

Thus, with any battery and microinverter solution, you want to provide redundant methods to regulate the charge to the battery. You can use a voltage-controlled relay to shut off the microinverter system when the battery reaches a voltage within the manufacturer’s limit, or a series of relays to taper the charge to the batteries. For additional battery protection, use a dump load to drain excess power out of the batteries in the case of overcharging. Do this by using some of the stored power to heat water or air with a listed and approved heating element.

So in short, using microinverters and energy storage together is very similar to using string inverters with energy storage. You simply swap out some electronics for others. You can do this with new and old microinverter systems. As is the case with any system, you want to make sure everything is matched and configured properly.

Related Posts

SimpliPhi Batteries Hit the Road with the Oscillation Transia Film Festival to Promote Renewable Energy

SimpliPhi batteries travel the US with the Oscillation Transia Film Festival, powering equipment as

SimpliPhi CEO Selected to Join Elite Group of Social Entrepreneurs for Immersive U.S. State Department Accelerator Program

Exclusive group selected as best to solve 17 Sustainable Development Goals established by UN.

SimpliPhi and AccESS Turn Heads at Intersolar North America 2017

In San Francisco at Intersolar North America this July, the SimpliPhi team was busy

Power Outages and the Failure of Grid-Tied Solar

Solar not always the best choice as backup for an unreliable grid. Many disappointed

It’s Time… and It’s Life Changing for Students of Pacific Island Schools

SimpliPhi Power & DPA Solar bring reliable, renewable power generation & storage to children

Grid-Tied vs. Behind-the-Meter Energy Storage: Putting Power Back in the Hands of End-Users

During grid failure, behind-the-meter assets owned & controlled by end-user allow systems to operate

Q&A with SimpliPhi’s Newest Team Member, Jordan Little

SimpliPhi is excited to welcome our new Applications Engineer Jordan Little! Jordan shares her

How SimpliPhi is Joining Forces in the Fight Against Australia’s Possible Battery Ban

SimpliPhi’s CEO traveled to Australia & NZ to meet distributors, power companies, manufacturers engaged

Historic Super Bowl Save in Hawaii by SimpliPhi Power Batteries

Before either team would score their first points during the historic Super Bowl LI,

Price vs The True Cost of Lithium-ion Batteries Simplified

Determining the Levelized Cost of Energy (LCOE) over a battery’s useable lifetime is more

PHI Batteries Prove Ideal Drop-in Replacement for Lead Acid Batteries

SimpliPhi Power is the only lithium-ion battery manufacturer that offers a direct drop-in replacement

Recapping a Whirlwind Week at Solar Power International 2016

Solar Power International was a successful and busy week for SimpliPhi Power! Much like last

SimpliPhi Energy Storage Plus Company Vision Honored by Gold Stevie Award

SimpliPhi Power has joined elite list of businesses honored by the Stevie Awards for

Celebrating the Innovation Behind a Product: A Recap of the 2016 Edison Awards

This month, we were honored by the 2016 Edison Awards with a Silver award

SimpliPhi Joins Clinton Global Initiative Supply Chain Event at Hewlett-Packard

SimpliPhi’s CEO Catherine Von Burg attends Clinton Global Initiative’s “Making Matter Matter: Supply Chain

How to Sell Energy Storage, Manage Customer Expectations & Optimize Security

Step-by-step assessing & meeting the needs of the customer leads to energy storage installations

SimpliPhi Power Makes the TOP 100 Companies in Energy Storage News and Solar Business Focus for 2016

SimpliPhi Power is pleased to be listed as one of the Top 100 companies

SimpliPhi Participates in RAND Symposium – Policy Options for Better Service Outcomes from the Future Electric Grid

Policy Options for Better Service Outcomes from the Future Electric Grid, the RAND Symposium

10 Questions Solar Installers Should Ask When Buying a Battery

With new storage options frequently coming to the market, understanding and comparing them can

The Uncommon Benefits of Low-Voltage Microgrids

by Chris Beitel, Chief Operating Officer, SimpliPhi Power As solar energy continues to proliferate and

Measuring the True Costs and Benefits of Energy Storage – Part Two

In last month’s issue, Part One of this series began covering how checking a

Cheap Lithium-ion Batteries in Hoverboards Raise the Spectre of Thermal Runaway Again

Over the holiday season Hoverboards emerged as the year’s “must-have” gift for consumers. This

Measuring the True Costs and Benefits of Energy Storage – Part One

When comparing battery options, be it lead acid, lithium ion, zinc bromide, flow, or

Energy Storage Tech Talk, with SimpliPhi CTO Stuart Lennox

Stuart Lennox – CTO At SimpliPhi Power, we know that our innovative energy storage technologies

Join us for the SimpliPhi Power Storage On/Off Grid Optimization Workshop at SPI 2015

Solar Power International (SPI) 2015 in Anaheim, Calif., is right around the corner. The

Challenging the Energy Industry Status Quo: A Recap of AREDAY 2015

Earlier this month, our CEO Catherine Von Burg and our COO Deborah Keiser were

The Energy Storage Origins of SimpliPhi Power

As you may have noticed, we weren’t always called SimpliPhi Power. In fact, we

Why Phi? Or, What’s in a Name?

The new company name represents our desire to capture in our brand what our

To Our Customers, Partners, Investors, Shareholders and Friends of OES

In order to more effectively position our technology for what we anticipate will be