SimpliPhi ESS is a new, modular home energy storage solution. Image courtesy of SimpliPhi.
SimpliPhi Power is a battery manufacturer with a long history of successfully providing energy storage solutions to the off-grid and DIY communities. The company is now partnering with Briggs & Stratton to offer a home Energy Storage System (ESS) that combines a hybrid solar inverter and batteries for grid-tied and off-grid applications. The SimpliPhi ESS is scalable and can be customized in size to serve anything from small homes to huge commercial buildings.
SimpliPhi’s products are designed to provide daily cycling for solar self-consumption as well as backup power for emergencies. The ESS can operate in off-grid and grid-tied settings and offers excellent performance, safe and non-toxic materials, and a 10-year warranty to protect your investment.
SimpliPhi’s batteries are DIY-friendly, with application engineers ready to provide service to anyone who needs it, but many full-service installers also carry them. All the batteries described below are available from distributors at retail or wholesale prices.
If you’re looking for a home energy storage solution, SimpliPhi should be on your shortlist. Here are the details:
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- SimpliPhi is a battery company with a long history of innovation and a commitment to quality that was acquired by Briggs & Stratton in 2021.
- The company offers many energy storage solutions, from portable emergency power kits to high-voltage commercial and industrial storage systems.
- The most interesting SimpliPhi product for homeowners is the new Energy Storage System (ESS), a modular battery storage system that can provide backup power and cycle daily from any source of electricity, including solar panels, generators, or the grid.
- The SimpliPhi ESS competes with solar batteries from well-known manufacturers like Generac, LG, and Tesla and rises above the industry standard for longevity and reliability, but at a somewhat higher cost.
Company history
The company that would become SimpliPhi got its start in 2001 when founder Stuart Lennox decided to repurpose lithium-ion battery packs used in early e-bikes to make mobile battery packs for the film and television industry. These early products became the industry standard for portable battery packs, and the company looked for ways to expand, using lithium ferro phosphate (LFP) batteries to create new products for the home and commercial markets.
By 2021, SimpliPhi had a product line of LFP batteries known for their longevity and performance. The brand was acquired in September of that year by generator company Briggs & Stratton, which itself was recently acquired and re-invigorated by private equity firm KPS Capital Partners.
Briggs CEO Steve Andrews saw SimpliPhi as a perfect fit for his company’s new focus on being “power application experts.” Andrews says Briggs no longer relies solely on the internal combustion engines used in its generators but instead provides solutions for power in all settings; however it makes sense.
A little less than a year later, the company announced SimpliPhi ESS, which is now available for purchase across the United States from both stores and partner installers.
SimpliPhi ESS
An image showing how the ESS can be scaled in capacity and power output. Image courtesy of SimpliPhi.
The SimpliPhi Energy Storage System (ESS) is a new customizable battery storage solution. Like many energy storage systems on the market today, SimpliPhi ESS is a modular solution, meaning it has core components (batteries, inverters, and control systems) that can be put together in several different configurations, from small-scale home battery backup to energy storage systems for very large buildings.
When all the components are used together, the SimpliPhi ESS provides a smart, connected, and convenient solution for homeowners to monitor and manage their solar and battery storage systems.
Here’s our interview with SimpliPhi President Catherine Von Burg at the 2022 RE+ Conference in Anaheim, California:
Cost
As described above, the SimpliPhi ESS can scale up from a very small home system to a very large commercial solution, so it’s not possible to assign a single price. We can say that the average homeowner would likely be happy with a 14.7 kWh system consisting of one inverter and three battery modules, which would cost around $17,000 before installation.
Here is a look at prices for some of the most common ESS capacities:
| Storage capacity | Components | Best for | Retail cost |
| 4.9 kWh | 1 inverter, 1 battery | Small home backup / critical loads only | $9,000 |
| 14.7 kWh | 1 inverter 3 batteries | Average home backup / daily cycling | $17,000 |
| 29.4 kWh | 2 inverters, 6 batteries | Very large home backup | $30,500 |
We listed retail prices in the table above, but the SimpliPhi ESS is also sold by qualified installers who can take advantage of bulk buying through distributors. The relative cost can also be reduced if you plan to add the SimpliPhi ESS to a new solar panel installation because the SimpliPhi inverter can take the place of a different solar inverter.
Look below for how these costs compare to SimpliPhi’s competitors in the energy storage market.
Components
There are three main components of an ESS ecosystem: a 4.9 kilowatt-hour (kWh) battery module, a 6 kilowatt (kW) hybrid inverter, and the EnergyTrak control system. Together, these components accept input from solar panels, the grid, and backup generators; store energy in the batteries for later use, and customize how that energy is used.
SimpliPhi 4.9 kWh battery
The SimpliPhi ESS battery module comes in one size that can hold up to 4.9 kWh of electricity. Up to four batteries can be wired in parallel and connected to a single SimpliPhi ESS inverter, and up to nine inverters can be wired together. A maximum of 72 batteries can be wired together in this way, holding 352.8 kWh of electricity.
These 48-volt batteries are made with high-quality lithium ferro phosphate (LFP) cells that SimpliPhi claims can withstand up to 10,000 charge/discharge cycles. That is a very long cycle life—an average of around 2.7 cycles per day for the 10-year warranty period.
| Battery specifications | |
| Rated kWh DC Capacity | 4.9 kWh DC* |
| Max. Surge Discharge Rate (10 minutes) | 100 amps DC (5.1 kW DC) |
| Max. Continuous Charge/Discharge Rate | 48.5 amps DC (2.48 kW DC) |
| Depth of Discharge (DoD) | up to 100% |
| Cycle life | 10,000+ cycles (@ 80% DOD) |
| Charging temperature | 32° to 120° F (0° to 49° C) |
| Mounting | Wall-mount only |
| Dimensions | 23 x 28.5 x 8.5 in (30 in H w/terminals) |
| Weight | 160 lb (73 kg) |
*Maximum capacity is 4.9 kWh, but SimpliPhi recommends 80% DoD, which is 3.9 kWh.
As shown in the table above, SimpliPhi estimates the 10,000 cycle lifespan at 80% depth of discharge, meaning each charge/discharge cycle would only be 3.9 kWh of electricity, leaving 1 kWh in the battery to prevent degradation.
It’s important to note that SimpliPhi makes no claim of cycle life or total battery throughput (measured in megawatt-hours) in its ESS Warranty. Instead, the warranty covers “manufacturing defect(s) in materials and workmanship” for 10 years. That’s a bit of a red flag because it doesn’t explicitly protect the system owner if the capacity of the batteries decreases more rapidly than expected. We like warranties to be explicit about how they protect the system owner.
To be clear, SimpliPhi products have proven to be robust and long-lasting in the field for many years—we are simply pointing out where the company’s warranty doesn’t measure up to industry standards. Brands like Generac and Tesla provide throughput warranties for their batteries that guarantee they will retain a certain capacity as the batteries are used over a large number of cycles.
SimpliPhi 6 kW inverter
The SimpliPhi 6 kW inverter is a fairly standard hybrid inverter that can accept up to 7.5 kW of solar input and charge batteries at up to 100 amps and 62 volts (6.2 kW). The inverter can be paired with any battery with a battery management system (BMS) that uses the CANBUS communications protocol, but SimpliPhi says it is specifically designed to work with the 4.9 kWh ESS batteries, as well as the company’s PHI 3.8 and AmpliPhi 3.8 batteries.
Like any other inverter, the SimpliPhi unit can work without batteries in a grid-connected setup. When paired with batteries, the inverter has several storage modes that allow its owner to specify how the energy stored in the battery will be used.
SimpliPhi ESS storage modes:
- Uninterruptible power supply (UPS) with 8 ms switch over time
- Solar self-consumption (i.e. daily cycling)
- Time-of-use (TOU), which reserves stored energy for when grid power is most expensive
- Off-grid backup
In a power outage, the inverter can output 6 kW continuously and surge up to 9 kW for 5 seconds (and even 12 kW for 100 milliseconds) to start motors in appliances like air conditioners and well pumps. If more power is needed, adding more inverters increases the potential output of the system by those numbers.
Another important feature of the SimpliPhi inverter is automatic generator start. If the inverter detects batteries dropping below a specified set-point when the grid is down, it can automatically start any backup generator that has a 2-wire start in order to charge the batteries.
When the batteries have charged to a specified level, the inverter shuts the generator off until it is needed. With this functionality, it is possible to run the SimpliPhi ESS in off-grid mode using solar panels and a backup generator indefinitely.
EnergyTrak control system
The SimpliPhi inverter and batteries work together to use and store electricity, but EnergyTrak is the brains that make the SimpliPhi ESS work. EnergyTrak is a hardware and software solution that professional installers use to commission, monitor, and maintain their customers’ ESS installations. Homeowners use the EnergyTrak app to manage and control their systems remotely.
EnergyTrak shows how power is being generated, used and stored within the home. Image source: Briggs & Stratton
The EnergyTrak mobile app (available on Google Play and Apple’s App Store) lets homeowners see solar generation, battery storage level, and power consumption in real time. It also lets users switch between the different storage modes listed above. This can be a very handy feature: in the case of a coming storm, you might want to switch from TOU or self-consumption mode to UPS mode to maintain extra battery capacity in case of a power outage.
How the SimpliPhi ESS compares to other home batteries
SimpliPhi ESS and some of its major competitors from Generac, LG, and Tesla.
When we compare batteries to each other, we look at a few factors:
- Functionality
- Quality and longevity
- Warranty protection
- Cost
In this case, we’ll be judging the SimpliPhi ESS against the top batteries in the industry, from Generac, LG, and Tesla.
Functionality
When it comes to functionality, the SimpliPhi ESS meets or exceeds industry standards. It offers excellent efficiency, retrofit and new installation capabilities, control over battery discharge modes, and generator auto start.
The one area where SimpliPhi currently lacks is participation in battery incentive programs like demand response and virtual power plants. Thankfully this problem can be solved with software updates, and SimpliPhi is working on inking deals to get their batteries added to programs around the country.
Quality and longevity
When it comes to quality, few people in the solar industry would argue that there’s a higher-quality LFP battery than SimpliPhi’s. The company’s products are proven performers around the globe, including being used by the Department of Defense in support of U.S. troops in Afghanistan.
In addition, LFP battery technology is already significantly preferable to lithium NMC batteries used in Generac, LG, and Tesla batteries. NMC batteries use toxic metals mined in conflict-ridden areas and often need external cooling systems to lower their risk of thermal runaway (which can cause a fire). LFP batteries suffer from none of those problems.
Warranty protection
This is where we feel SimpliPhi and Briggs & Stratton could do the most to improve and push the ESS to the top of the industry. The 10-year warranty for the company’s other batteries has clear language about the batteries’ energy retention at 10 years after the purchase date.
Why, then, does the 10-year warranty for the SimpliPhi ESS not offer the same assurances? It’s honestly kind of mind-boggling. That said, we have no reason to doubt the batteries won’t perform exactly as well as the company's other offerings. We just like things in writing.
Most battery other companies offer “throughput” warranties that promise their batteries will retain a certain percentage of their capacity until they have been charged and discharged a certain number of kWh. We’d welcome an update to the SimpliPhi warranty that promises at least this much.
Cost comparison
Given their reputation for functionality, quality, and longevity, you might expect the SimpliPhi ESS to be more expensive than the competition. You’d be correct in that assumption. Here’s a quick look at retail prices for these batteries:
| Battery | Capacity | Cost |
| SimpliPhi ESS | 14.7 kWh | $17,000 |
| Generac PWRcell M5 | 15 kWh | $16,500 |
| LG Chem RESU 16H Prime | 16 kWh | $9,500* |
| Tesla Powerwall | 13.5 kWh | $9,200 |
* The LG Chem RESU battery does not include an inverter, which can add $1,500 to $3,500 to the cost.
Of course, you may not pay retail price for your SimpliPhi ESS. If you find an installer that can get it wholesale, they will offer a total installed price that includes all the work to connect and commission the system and keep it running for many years to come.
Other SimpliPhi batteries
Other SimpliPhi batteries (L-R: PHI 1.4, PHI 3.8-M, AccESS Sol-Ark). Image courtesy of SimpliPhi.
In addition to its new ESS lineup, SimpliPhi offers many other products that use the same LFP battery technology. The PHI and AmpliPhi lines of batteries offer solutions in 12-, 24-, and 48-volt flavors. Its fully-integrated systems combine these batteries with Sol-Ark or Schneider inverters in custom enclosures, with several capacity sizes available.
PHI and AmpliPHI batteries
The PHI and AmpliPHI product lines are standalone batteries made to work with some of the leading inverters and charge controllers on the market. Like the ESS, these batteries come with 10-year warranties and the same 10,000 cycle-life claims (again at 80% DOD).
SimpliPhi says all its PHI batteries are “compatible with all industry-standard charge controllers,” while the AmpliPHI line is compatible only with Sol-Ark, SMA, and Schneider inverters. The company provides Integration guides for many brands on its product documentation page.
Here are some details about each of the four current batteries offered in these product lines:
| PHI 730 | PHI 1.4 | PHI 3.8-M | AmpliPHI 3.8 | |
| Capacity | 730 Wh | 1.4 kWh | 3.8 kWh | 3.8 kWh |
| DC Voltage | 12 or 24 | 12 or 24 | 24 or 48 | 48 |
| Dimensions (L x W x H) | 11.25 x 5.25 x 6.25 in | 11.25 x 9.25 x 7.25 in | 13.5 x 14 x 8 in | 13.5 x 14 x 8 in |
| Weight (lbs) | 17.14 | 33 | 86 | 86 |
| Notes | Drop-in replacement for lead acid | Max output 0.69 or 0.73 kW DC based on battery voltage | Max output 1.9 or 1.92 kW DC based on battery voltage | Advanced BMS to prevent overcurrent events |
Integrated systems
If building a system using standalone batteries, inverters, and home storage system doesn’t sound like fun to you, you can also purchase one of SimpliPhi’s Integrated Systems, which come pre-programmed and include an inverter (either Sol-Ark or Schneider) and either PHI or AmpliPHI batteries in a custom enclosure.
An integrated system from SimpliPhi is almost like a “just add solar” solution, and the ExprESS PHI system is even on wheels and can be moved from place to place as a portable power solution.
SimpliPhi offers four current integrated systems. Here’s a little about each of them:
| AccESS PHI Sol-Ark | AccESS PHI Scneider | AccESS AmpliPHI Sol-Ark | ExprESS PHI | |
| Capacities offered | 15.2, 19, or 22.8 kWh | 15.2 kWh | 19 kWh | 7.6 kWh |
| Built-in inverter | Sol-Ark 12K | Schneider Conext XW Pro | Sol-Ark 12K | Magnum Energy |
| Continuous output power | 12 kW combined, 9 kW in off-grid mode | 6.8 kW | 12 kW combined, 9 kW in off-grid mode | 4.4 kW |
| Dimensions (H x W x D) | 29.5 x 76 x 20 in | 29.5 x 76 x 20 in | 29.5 x 76 x 20 in | 41 x 36 x 17 in |
| Weight (lbs) | 944, 1,030, or 1,116, depending on capacity | 944 | 1,030 | 411.5 |
| Mounting | Free-standing or Pad-mounted | Free-standing or Pad-mounted | Free-standing or Pad-mounted | On casters |
Where to buy
SimpliPhi sells its products through wholesale and retail distributors on five continents. In the USA, it’s easy for end users to buy SimpliPhi batteries for the retail prices listed above, but professionals who have accounts at wholesale distributors will offer different prices based on their costs and added charges for installation and commissioning.
Here are some of the best places to get SimpliPhi batteries:
Find an installer
If you don’t have a ton of experience dealing with voltages that can kill you, your best bet is to find a licensed professional installer who carries SimpliPhi products. You can do that via our website by using the solar calculator to get solar quotes from installers in your area.
You’ll benefit from having the job done by a professional and letting them be responsible for making sure your battery bank is working properly on day 1 and day 3,650. Choose a good installer by getting multiple quotes and asking the right questions.
AltE Store
If you’re an experienced DIYer or can learn highly technical information and do the labor yourself, installing a SimpliPhi battery system can be a good choice. One of the best places to do that is the AltE store, which has sold solar supplies directly to consumers since before the calendar switched centuries. AltE has tons of educational content and helpful technical salespeople to help you on your journey.
Bottom line: is a SimpliPhi battery right for you?
When it comes to long-lasting, high-quality batteries, SimpliPhi is hard to beat. They have a well-earned reputation for longevity and reliability, but we wish they’d back that up a little more explicitly in their warranty language. Still, 10 years of protection against defects of product and workmanship is a good start.
SimpliPhi batteries will cost a little more than other offerings on the market, but their functionality is right up there with the best, and their total lifespan should make the extra cost worth it. Additionally, the ESS should soon be able to join battery incentive programs like demand response and virtual power plants if you’re lucky enough to live in one of the areas offering them.
If you’re the kind of person who wants the best of everything with price as no object, we recommend SimpliPhi batteries.
Thi Deremer
Solar Policy Analyst and Researcher
Ben Zientara is a writer, researcher, and solar policy analyst who has written about the residential solar industry, the electric grid, and state utility policy since 2013.