Exact Solar, a solar engineering, installation, and service company located in the Greater Philadelphia region, has provided support to a variety of battery projects for many years. Our team has worked on everything from simple “critical load” single battery backup applications to more complex whole-home backup projects with unique and challenging requirements. Through our extensive experience, we have noticed that the batteries currently available on the market are often expensive and limited in their capabilities. This means that many customers are faced with the difficult decision of choosing between their budget and the loads they can back up during a power outage. It can be frustrating for customers to feel like they have to constantly compromise between their budget and desired outcome.

This creates an all-too-common dance of considering many different size and configuration options to find the right balance between budget and performance or capability for our customers. Essentially, “how much budget to back up what loads, for how long?”. We, of course, embrace our role in explaining the options and guiding our customers to an ideal outcome for their unique situation, but from all this experience, we’ve been hoping to soon see a battery that would tip the scales in terms of improved performance and more readily meet what we believe the more common use cases are for battery backup.

We are excited to share that with the new Enphase 5P battery, we truly believe we now have a viable solution that much better aligns budget versus need and we have found the customer reception to it to be excellent.

Why the Interest in Battery Backup?

Solar battery backup interest has grown significantly over the last several years. Some of this is driven just by growing awareness of the option to have this, growing general adoption of solar, and improving product availability. However, the main driver is the continued trend of power outage occurrences. In the northeast, we continue to see semi-frequent short-term outages, as highlighted by many, including Time in 2022, Fortune in 2023, and many others.

According to SolarPowerWorld – solar coupled with storage is on the rise — 17.1% of the quoted solar systems on EnergySage included batteries in 2022, up from 9.5% in 2020. Now with more grid programs and a stand-alone storage ITC, battery adoption in the United States is climbing to new heights.

How Does a Battery Help You if You Have Solar?

If you have solar PV on your home, but no battery backup, regulations require the solar inverter to shut the solar down during grid outages.The reason for this is to prevent the system from feeding back to the grid while grid workers repair power lines. All US inverter manufacturers are required to comply with this regulation. However, with the addition of a solar battery, you can “island” your home. An automatic transfer switch senses grid loss, temporarily disconnects from the grid, and allows the solar PV system to stay in operation. This means that a solar battery not only provides backup power during an outage, but also enables your solar PV system to continue operating as long as there is sunshine. The solar PV system can partially power your home and recharge the batteries simultaneously.

What Can I Backup With a Solar Battery?

When it comes to backing up power with a solar battery system, it’s important to understand their limitations. To maximize their efficiency during power outages, we install a “critical loads sub-panel.” This sub-panel functions as a smaller circuit breaker panel that remains active and connected to the battery, even when the main panel shuts down due to a grid failure.

To ensure a seamless power supply to essential appliances and devices, a careful planning process takes place. Ahead of time, a meticulous selection of critical loads is made, and these loads are transferred to the designated sub-panel. These specific loads are the only ones powered by the battery during an outage, allowing for efficient utilization of the available energy.

At Exact Solar, our salespeople and engineers are extensively trained to collaborate with customers. They perform detailed calculations to ensure that the critical loads chosen are well-matched to the total capacity of the battery bank. Additionally, our systems are designed to be scalable, allowing for the stacking of multiple batteries if necessary. This approach guarantees that our customers receive a reliable and tailored solar battery solution, customized to their specific needs and requirements.

EnergySage’s website has a great explainer on critical load panels and why they are needed for battery projects.

A Quick Primer on Battery Specs

As a quick background context on battery specs, the key data points you want to gather on batteries are the input/output power rating (kW) versus the storage volume (kWh) of energy. We always use the analogy of a tank with a spout when explaining this to clients. The size of the spout controls how much water can come in/out of the tank at any given time. No matter how small or big the tank is, the spout controls what you can get at any given moment in time. However big a tank might be, if it has a small spout, the flow rate is constrained. This analogy works very well when thinking about batteries and electricity and explains why even larger batteries can only have a limited number of electrical loads that they back up. No matter how large the battery, if the startup power surge, or inrush, of loads connected to the battery, exceeds its power rating, it can trip off the battery or overload it. Many customers have felt frustrated with the cost of batteries and the limited amount of electrical loads that can be backed up. The 5P tips the scales considerably in this regard, offering a much better balance of power rating kW to storage capacity (kWh), meaning more loads can be supported in a backup scenario, and the customer’s goals can be achieved at a more reasonable budget.

So, Why Are We Excited About the Enphase 5P Solar Battery?

Exact Solar sees the improved kW continuous power and short-term power rating (for inrush currents) as a tremendously important design decision by Enphase, and we’re already seeing this battery being asked about by many incoming new customers. Exact Solar has already installed 3-4 projects with the 5P battery just this fall (2023) and has many more projects lined up for the winter. So far, our technicians like working with it, and our engineers and salespeople are finding it is better suited to the project goals our customers have.

One of the biggest reasons for this is that many customers prioritize having more loads backed up or able to be backed up but with a focus on a shorter duration of power outage. In other words, this is less for those preparing for long-duration total outages (doomsday scenarios) and more for those who seek the reliability and convenience of whole-home backup for shorter duration outages, where most of their home power loads remain on during outages and the inconvenience of power loss is greatly minimized). More and more, these seem to be the incoming requested scenarios, and the 5P provides a better budget/capability fit for these customers.

What is Inrush Current, and Why Does it Matter for Solar Batteries?

Inrush is a higher amp load that occurs when an inductive motor load (think pump or compressor) turns on. This is the point of highest power draw, and while it’s short in duration it can trip off a battery if it overloads the battery’s short-term power rating. A home often has many of these loads – think of any fridge/freezer compressors, HVAC compressors, sump pumps, well pumps, etc.

Let’s Do Some Math to Show What the Enphase 5P Can Do

Looking at the spec sheets for the Enphase 5P battery, each 5 kWh battery (meaning its storage volume is 5 kWh of electricity) can provide 3.84 kW of continuous power and 7.68 kW of short-term power capability (meaning it can handle the short-term inrush during pump or HVAC compressor startup). 7.68 kW is 7,680 watts, which at 240 volts (residential power grid voltage) gives you 32 amps of power or 64 amps of 120-volt power.

Most 200 amp panels are not fully loaded, which we have seen repeatedly when we do field testing for customers to determine how much power their home draws when everything is forced on. As such, 3-4 Enphase 5P’s can effectively provide whole-home backup for most homes with 200 amp main panels (Exact Solar’s engineers will do a custom load analysis to help confirm this and provide specific guidance for each project).

Exact Solar and Enphase 5P

Exact Solar is an Enphase Gold Installer (as well as a SolarEdge certified installer, Tesla Powerwall Certified, and Sonnen Battery Partner). We have installed many projects with Enphase’s 2nd generation battery line (using the 3T or 10T batteries and their System Controller 2), and now we are actively scoping, selling, and installing projects with the 3rd generation product line (Enphase 5P battery and System Controller 3). We also have experience with a lot of other battery systems. While we do not exclusively sell or offer any products (we especially are proud of our position as product agnostic), we do like to recommend things that particularly impress us and truly help our customers. We are currently feeling that way about the Enphase 3rd generation battery product line and their 5P batteries, and we believe this to be a product that will open up the market for solar batteries, more closely meeting the combined budget/performance needs we hear many customers asking for.

Exact Solar and Enphase 5P Customer Project Spotlight: Sergey

At Exact Solar, we really enjoy opportunities to feature our customers and their stories, especially when we think it will benefit others. We are currently installing the Enphase 5P battery system for a previous solar customer from last year, Sergey, who agreed to share a few thoughts on why he’s so excited about the Enphase 5P, and why he asked us for it specifically. Sergey has the benefit of being an electrical engineer, so he already knows all-too-well, the importance of inrush current draws during motor startup, and the advantage Enphase 5P batteries offer to him with higher power ratings per kWh of storage volume.

Sergey already had an Ephase IQ8 microinverter system for his solar. Segey is now adding a (4) battery Enphase 5P system, being installed this fall of 2023. We asked Sergey why he was so excited to get the 5P (3rd generation) Enphase battery system.

“To me, the reasons were simple:

First, because two of these batteries can start my 3.5-ton air conditioning unit, which has a higher inrush amp draw during startup. Whereas two of the 2nd generation Enphase batteries (the 10P’s) couldn’t do it would have cost more. Also, the new Enphase 5P batteries have a 15-year standard warranty, whereas the old 10P product line had a 10-year standard warranty with the option to purchase 5 additional years for an extra cost. Finally, the new 5P batteries have a better Enphase System Controller 3 that uses wired communication which is more reliable than old wireless communication between old 10P batteries and System Controller 2.

As far as why Enphase 5P batteries versus other competitive options available on the market… “As far as I am concerned, there is only one real competitor, which is the Tesla PowerWall 2. However, it has a 7.5 kW inverter limit (max power rating for input/output power) and it doesn’t interface natively with my existing Enphase IQ8 microinverters. Additionally, two PowerWall 2 batteries installed would have cost more than four Enphase 5P installed.  The warranty is only 10 years on Tesla Powerwall, I believe. Case closed.”

Where Can I Learn More About the Enphase 5P 3rd Generation Battery System?

Enphase is known for its great online production descriptions, specifications, and videos. They have a thorough hub on their website all about the new 5P battery product line, which you can view here. They also have a more detailed video geared for installers reviewing the battery and its installation here.

Solar Battery Tax Credits

The Inflation Reduction Act (IRA) of 2022 strengthened the battery tax credit to 30% of the installed cost of the battery system, whether installed coupled with solar or installed stand-alone. This is excellent news for the growing battery market and greatly subsidizes the cost of adding a battery system to your home, whether as part of a solar project or as a separate project. Check out our blog article here to learn more about the Inflation Reduction Act.

Talk to an Exact Solar Sales Engineer today!

Exact Solar’s sales engineers are all trained on Enphase’s product line and the new 5P batteries, as well as the wide range of other solutions offered by Exact Solar, including SolarEdge, Sonnen, Tesla PowerWall, and much more. As mentioned earlier, we are customer-focused and product-agnostic, so while we do have a lot of excitement over the Enphase 5P battery, we’ll only recommend it if we believe it fits your application and your project goals. If you’re interested in a low-pressure conversation or maybe even just curious to learn more about solar in general, don’t hesitate to reach out to us today.