KOHLER Power Reserve review

The KOHLER Power Reserve complete review

Kohler is a well-known and respected name across multiple industries, from sinks and toilets to engines and generators. Founded in 1873 in Wisconsin, Kohler has been producing generators since the 1920s. Just about 100 years later, they entered the residential energy storage market with the KOHLER Power Reserve battery line, released in May of 2021. The Power Reserve is an energy storage system available in both AC- and DC-coupling models and comes in a range of sizes so you can customize it to fit your home’s energy needs.

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Key takeaways


  • The KOHLER Power Reserve comes in three different models with usable capacities of 10 kWh, 15 kWh, and 20 kWh.
  • The battery has a lithium-iron phosphate chemistry and is able to be installed indoors or outdoors.
  • The Power Reserve battery can be either AC- or DC-coupled: the system comes with an integrated hybrid inverter. 
  • Explore your solar-plus-storage options today on the EnergySage Marketplace

How does the KOHLER Power Reserve work?

The Power Reserve pairs well with solar panel systems, especially if your utility has reduced or removed net metering, introduced time-of-use rates, or instituted demand charges for residential electricity consumers. Installing a storage solution like the Power Reserve with a solar energy system allows you to maintain a sustained power supply during both day and night, as long as you store enough power from your solar panels when the sun is shining.

As with many other home battery products, the Power Reserve is sized for day-to-day use at your home and is primarily designed to be paired with a solar panel system. When your solar panels produce more electricity than you can use in your home, you can store the excess electricity in the battery system instead of sending it back into the grid. Later, when your panels aren’t producing enough electricity to meet your home’s needs, you can use the stored energy in your battery instead of having to buy it from your utility company.

Key things to know about the KOHLER Power Reserve 

The Power Reserve is an adaptable battery system that is compatible with any solar installation. It has a built-in, hybrid inverter that allows it to be coupled with an AC or DC system. It was designed to be flexible and provide you with as many options as possible when developing a solar-plus-storage system that works for your home.

When evaluating the Power Reserve, there are various important metrics and technical specifications to keep in mind. Among the most important are the size of the battery (power and capacity), its chemistry, depth of discharge, and roundtrip efficiency

Size

The Power Reserve comes in three sizes of 10, 15, and 20 kilowatt-hours (kWh). Two important metrics to keep in mind when comparing the KOHLER Power Reserve to other home storage options are power and usable capacity. Power (measured in kilowatts, or kW) determines the maximum amount of electricity that can be output at a single time, while usable capacity (measured in kilowatt-hours, or kWh) is a measure of the maximum amount of electricity stored in your battery on a full charge. See the table below for the Power Reserve’s power and usable capacity ratings for the various models.

KOHLER Power Reserve size

 Power Reserve 10Power Reserve 15Power Reserve 20
Max. power rating - off-grid (kW)7.6 kW7.6 kW7.6 kW
Max. power rating - on grid (kW)9.1 kW9.1 kW 9.1 kW
Usable capacity (kWh)10 kWh15 kWh20 kWh

The Power Reserve is modular, meaning you can stack multiple batteries together if you want a larger backup capacity. Kohler has 5 kWh expanders available, so you can expand the capacity of the Power Reserve 10 in 5 kWh increments up to 20 kWh (the largest capacity possible for a Power Reserve system). 

Deeper dive into power and usable capacity


Think of your battery like water running through a pipe. The usable energy capacity is the amount of water available to push through the pipe, while power is the size of the pipe itself. Larger pipes allow more water to flow through at once, which depletes the water faster. Similarly, a battery with a high-power rating can deliver more electricity at one time, but will burn through its available energy capacity faster too.

A battery’s power determines what appliances you can run with it at the same time, while usable capacity determines how long those appliances can be run. Batteries with a higher power rating are capable of powering more robust appliances or many appliances at once, while batteries with a higher usable capacity can store more total energy and thus can run your appliances for longer periods of time without needing to recharge.

Basic functionality

The functionality of one solar power battery next to another can vary; some batteries have excellent off-grid capabilities, while others offer software solutions specific to rate arbitrage. Here are the important qualities of the KOHLER Power Reserve:

Backup power

The KOHLER Power Reserve comes with backup power capabilities. Kohler sells (separately from the battery-plus-inverter) an automatic transfer switch that allows the KOHLER Power Reserve to power your home and key appliances like heat/air conditioning, refrigerators, and lights when the grid goes down.

Chemistry

The KOHLER Power Reserve battery is a lithium iron phosphate (LFP) battery. This is one of the most common lithium-ion battery technologies, and for good reason: LFP batteries are known for their high-power rating, longevity, and safety. To learn more about how different lithium-ion battery chemistries stack up against one another, check out our overview of battery chemistry differences.

Inverter

Inverters are necessary to convert electricity from direct current (DC) which is generated by solar panels and stored in solar batteries to alternating current (AC) which is used by most household appliances. Storage systems can come with or without an integrated inverter – if your system doesn’t come with an integrated inverter, you’ll have to pair it with a separate, external inverter. 

If your system comes with a hybrid inverter, it can cover the production from your solar panels as well as the requirements of your storage system. Storage systems can also be either AC- or DC-coupled. While AC-coupled systems are generally easier to install if you’re retrofitting your storage system to an existing solar system, DC-coupled systems typically provide a higher overall efficiency. The Power Reserve comes with a built-in hybrid inverter that can be either AC- or DC-coupled (for systems with up to 12 kW solar), giving you flexibility in your system setup. It also comes with four built-in maximum power point tracking (MPPT) charge controllers, which prevent the battery from overcharging while delivering the maximum power possible from your solar array.

Outdoor rating

If you’re hoping to install your solar battery outside, you’ll need to make sure it’s weatherproofed and has an outdoor protection rating. The Power Reserve is designed to provide owners with as much flexibility as possible when it comes to installing, and has an outdoor protection rating that allows it to be installed outside.

Performance metrics

Two key ways to evaluate the performance of a solar battery are its depth of discharge and roundtrip efficiency

Depth of discharge (DoD) indicates the percentage of a battery’s energy that has been discharged relative to the overall capacity of the battery. Because the useful life of a battery decreases each time you charge, discharge, and re-charge it, many battery manufacturers specify a maximum DoD level for optimal battery performance. In general, batteries with a higher depth of discharge are considered higher quality products. The KOHLER Power Reserve  boasts a depth of discharge of 97 percent across all battery sizes, reflective of its safe and advanced LFP battery chemistry.

Roundtrip efficiency is a measure of the electrical losses involved with charging and discharging a particular battery. The higher the percentage, the more efficiently the battery is able to convert incoming electricity into stored electricity and then back into usable electricity. The Power Reserve has a roundtrip efficiency of 97.6 percent; this means that for every 10 kilowatt-hours (kWh) of electricity you put into the battery, you’ll receive 9.76 kWh of output.

KOHLER Power Reserve warranty coverage

KOHLER Power Reserve warranties


  • Warranty period: 10 years
  • Warrantied throughput: 3 MWh per kWh
  • Guaranteed end of warranty capacity: 70%
  • Check out this article for our in-depth review of the Kohler warranty

In most cases, homes with a KOHLER Power Reserve will charge and discharge their battery every day. So, how long do Power Reserves last? The Power Reserve comes with a 10-year, or 3 MWh per kWh throughput, warranty, and Kohler guarantees that the battery will maintain at least 70 percent of its capacity to hold a charge during that time period. 

Kohler’s battery technology is similar to other rechargeable batteries both large and small: as time goes on, the battery loses some of its ability to hold a charge. Think of how the battery life of a brand-new smartphone compares to one that is a few years old. As you continually charge and drain your phone’s battery, it starts to lose some of its ability to hold a charge.

The battery life of your Power Reserve will deteriorate in the same way. That isn’t an indicator of a product flaw – all batteries lose some of their ability to hold a charge over time after extended usage, whether it’s an electric vehicle battery, a home energy battery, or a rechargeable AA battery. This is why Kohler offers a warranty that guarantees a certain percentage of storage capacity.

If you want to compare individual battery models side-by-side, our battery Buyer’s Guide lets you select products and compare them based on efficiency, capacity, power, and more.

How much does the KOHLER Power Reserve cost?

A solar battery installation isn’t as simple as a list price for a component – depending on your electrical setup, among other factors, installation costs can vary widely. However, before installation cost, the Power Reserve 10 kWh costs $13,325, the Power Reserve 15 kWh costs $18,720, and the Power Reserve 20 kWh costs $23,440.

If you want to install a Power Reserve as part of a solar-plus-storage system, battery costs are just one part of the equation. A 5 kilowatt (kW) solar energy system costs anywhere from $9,000 to $15,000 depending on where you live and the type of equipment you choose.

That may sound like a lot of money, but installing a solar-plus-storage system can be a worthwhile investment. Whether or not the Power Reserve makes sense for you is determined by the way that your electric utility structures its rates, as well as your reasons for installing a solar battery.

In some cases, depending on where you live, you may have access to financial incentives that can reduce your home energy storage installation costs. For instance, if you live in California, you could get a cash rebate that covers most of your home battery costs through the Self-Generation Incentive Program (SGIP). Other states (such as Massachusetts) are in the early stages of evaluating battery storage performance incentives as well, and several states already provide cash rebates.

Can you go off-grid with the KOHLER Power Reserve?

Installing a solar-plus-storage system at your home is a great way to take control of your electricity bill, but it doesn’t mean that you’re completely disconnected from your utility. Going “off the grid” with solar batteries is actually a more expensive and complicated proposition than you might think. Most home batteries, including the Power Reserve, only have enough capacity to store a few hours of electricity. That being said, the Power Reserve could serve as a temporary backup when the grid goes down if you have a solar panel system to provide power.

Where to buy the KOHLER Power Reserve

Whether you want to install a Power Reserve or another home battery pack, you will most likely need to work through a certified installer. Adding energy storage technology to your home is a complicated process that requires electrical expertise, certifications, and knowledge of the best practices required to install a solar-plus-storage system correctly.

A qualified EnergySage-approved company can give you the best recommendation about the KOHLER Power Reserve and other energy storage options available to homeowners today. If you are interested in receiving competing installation quotes for solar and energy storage options from local installers near you, simply join the EnergySage Marketplace today and indicate what products you’re interested in your profile’s preferences section.

Find out what solar + storage costs in your area in 2022

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