Q CELLS Q.HOME complete battery review

Q CELLS is a popular solar panel manufacturer based out of Seoul, South Korea. Like many other solar panel companies, Q CELLS recently decided to expand their business into the energy storage space. Their new product, the Q.HOME ESS HYB-G1, is a modular energy storage solution that can help keep your lights on during power outages.

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The Q CELLS Q.HOME storage system 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. Installing a storage solution like the Q.HOME with a solar energy system allows you to maintain a sustained power supply during the day or 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 Q.HOME 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.

Q CELLS advertises their Q.HOME battery model as an "...energy storage solution [that] offers scalable storage capacity...and comes in a modular design for easy and fast installation." Additionally, a Q.HOME energy storage system can work with both AC-coupled and DC-coupled configurations, meaning it's a good option for those who want to install it at the same time as a new solar panel system or as a retrofit installation to an existing solar panel system.

Alongside the Q.HOME storage system, Q CELLS offers a Q.HOME web portal and ESS mobile app, which allows you to access Q CELLS' energy monitoring system online from your laptop or mobile phone.

When evaluating the Q.HOME storage system, 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 depth of discharge, and roundtrip efficiency.

Size

The Q.HOME is a modular system that allows you to connect up to three batteries under the same hybrid inverter and battery management system. Because of this, the Q.HOME comes in a variety of sizes.

Two important metrics to keep in mind when comparing the Q.HOME 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. The usable capacity of the system depends on how many batteries you include: on the lower end, the Q.HOME offers a usable capacity of 6.3 kWh, but you can add more batteries to reach up to 18.9 kWh of usable capacity. All configurations provide 5 kW of power output.

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 the number of appliances you can run from the battery concurrently, while usable capacity determines how long those appliances can be run. Batteries with a higher power rating are capable of powering more, bigger appliances (i.e., your HVAC system) 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.

Since the Q.HOME is a stackable and modular energy storage system, you can choose how many batteries you'd like to install based on your personal needs. For example, you might want to install multiple Q.HOME batteries for your home if you have higher energy needs and want to keep your home's most valuable appliances running during a long power outage. However, if your backup power needs are minimal, a single battery may suffice.

Basic functionality

The functionality of one solar battery next to another can vary; some batteries have excellent off-grid capabilities, while others offer software solutions specific to rate arbitrage. The suite of Q.HOME hardware and software products is designed to provide both of these services.

Q CELLS offers a bi-directional inverter, or hybrid inverter, alongside their Q.HOME. This inverter acts as both a battery inverter and a rooftop solar array inverter. This means that, as long as your contractor installs the correct components and the Q.HOME inverter, your Q CELLS Q.HOME battery system will be able to provide backup power for your home when the grid goes down and continue interacting with your home solar panel system if you have one.

Their monitoring technology is fully built-in to their Q.HOME inverter. With their built-in monitoring technology, Q CELLS's Q.HOME batteries and their associated parts can intelligently manage electrical loads throughout your house and appropriately pull energy from the battery when needed.

Performance metrics

Two key ways to evaluate the performance of a solar battery are its depth of discharge and round-trip 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–or cycle–your battery, many battery manufacturers specify a maximum DoD level for optimal battery performance. In general, batteries with a higher depth of discharge are considered better-quality products. The Q CELLS Q.HOME boasts a solid depth of discharge of 90 percent.

Round-trip efficiency is a measure of electrical losses involved with charging and discharging a battery. The higher the efficiency percentage, the more efficiently the battery is able to convert incoming electricity into stored electricity and then back into usable electricity. The Q CELLS Q.HOME has a high round-trip efficiency of around 90 percent; this means that for every 10 kilowatt-hours (kWh) of electricity, you put into the battery, you’ll receive 9 kWh of output.

In most cases, homes with a Q.HOME battery will charge and drain the battery every day. The Q.HOME comes with a 10-year warranty. During this time period, Q CELLS guarantees that the battery will maintain at least 60 percent of its capacity to hold a charge. Q CELLS also offers an energy throughput warranty – the 60 percent retained capacity after ten years is only valid if the total energy throughput over the ten-year period is less than either 13.5 MWh or 18.9 megawatt-hours (MWh), depending on the battery cell you install (4.5 kWh cells vs. 6.3 kWh cells). Summed up, your Q CELLS Q.HOME battery is warranted to retain at least 60 percent of its capacity by the time you hit a lifetime of 10 years or an energy throughput of up to either 13.5 MWh or 18.9 MWh, whichever happens first.

Importantly, Q CELLS' 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 Q.HOME battery 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, whether it's an electric vehicle battery, a home energy battery, or a rechargeable AA battery. This is why Q CELLS offers a warranty that guarantees a certain amount 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.

The cost of installing a battery isn't as straightforward as looking up the list price for an individual component–i.e., your battery. In fact, depending on your electrical setup, installation costs can vary widely. Q CELLS hasn't published pricing information for the Q.HOME yet, but according to EnergySage Marketplace data, most solar battery systems range from $5,000 to $7,000+. However, the price of the storage system is just one part of the equation – the average installed cost of a battery is closer to $11,000 to $18,000.

If you want to install the Q.HOME as part of a solar-plus-storage system, you'll also have to consider the cost of a solar panel system. 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 Q CELLS Q.HOME 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.

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 Q CELLS home battery system 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 Solar Marketplace today and indicate what products you're interested in your profile's preferences section.