Fortress Power is one of the rising stars in the solar industry and has established a name for itself as a manufacturer of quality solar power equipment. However, because they’ve only been around for less than a decade, many still have questions about this company, products, and reliability. We have answers to some of the most commonly asked questions about this company, including information about the Fortress battery bank, their batteries’ chemistry and functionality, and more. Keep reading to learn more about Fortress Power and its products!


What Does Fortress Power Make?

While many solar power manufacturers will build a full range of solar power equipment, Fortress Power specializes in solar energy storage. They design and manufacture solar batteries and battery banks and have contributed to the boom in solar-plus-energy system designs over recent years. Though this might seem like a narrow solar field, Fortress Power has settled into the niche nicely and provides a decent range of power storage options.


How Big Are Their Battery Banks?

As we just mentioned, Fortress offers a range of storage options, including battery banks of different sizes. They carry battery banks that range from the single-unit eVault, with a storage capacity of 18.5 kWh, and the eFlex, which is a modular solution; the eFlex offers incredible scalability, with each battery module offering 5.4 kWh of storage and stackable up to 15 units, or 81 kWh. As you can see, this allows virtually any solar application to add a battery bank of an appropriate size to meet their power needs.


What Inverters Do Their Batteries Work With?

Many new solar users think they need to buy a battery manufactured by the same company that builds their solar inverter, but that’s not true. Fortress Power is an approved battery partner of significant equipment manufacturers like Outback, Schneider, Sol-Ark, Magnum, SMA, and Victron Energy. However, their batteries should be compatible with any inverter with a DC input of 48V.

What Is the Chemistry of Their Batteries?

It’s always a good idea to know the chemical makeup of your solar battery since each chemistry has its pros and cons. Fortress batteries use Lithium Iron Phosphate, also known as Lithium Ferro Phosphate or LiFeO4. It is the safest type of lithium chemistry, as it doesn’t have ignitable cobalt in its makeup, which can cause battery fires. This chemistry also requires no cooling or ventilation and offers double the number of cycles compared to lithium-ion batteries.


Do Their Batteries Have a Warranty?

Yes, all Fortress Power solar storage batteries have a generous 10-year warranty. It is higher than most battery warranties, which can be as few as five years for many models.


How Do They Compare to Lead-Acid Batteries?

Lead-acid batteries have been used for many decades, not only since the advent of solar storage but in even older applications like vehicle starter batteries. While there’s something to be said for time-tested battery chemistry, the LiFeO4 makeup of Fortress batteries tends to be far superior. Here are just a few of the ways that they outshine the competition:

  • Greater round-trip efficiency than any other battery chemistry.
  • Extremely high number of life cycles at 80% depth of discharge.
  • Lowest cost per watt of any solar battery type.
  • No maintenance requirements.


While other battery chemistries have their advantages, Fortress Power chose to specialize in Lithium Iron Phosphate batteries for a reason; they’re simply the most efficient option out there and will likely be the solar storage option that’s most common in the future.


How Long Can It Back Up My House?

It is a difficult question to answer, as it depends on many factors: your energy usage and the size of the battery bank you plan to build. For example, let’s say you opt for the eVault, which provides 18.5 kWh of energy storage, as mentioned above. If you run an average of 3 kW of power for every hour you’re relying on the eVault. It will power your home for 6 hours without needing to be recharged. If you have more specific sizing questions about building a battery bank, we encourage you to contact our solar experts for assistance.


Do I Really Need Solar Storage?

Though this question isn’t specifically about Fortress Power, it’s one we hear a lot about in regards to solar batteries and storage in general. The answer to this is both yes and no. Your solar power system will function perfectly without a battery bank. However, you won’t be getting the most out of it. Adding a battery bank like the Fortress Power eVault or eFlex allows you to store excess solar energy to become more energy independent. Contact The PowerStore, Inc., to learn more about adding a battery bank to your system.