5 Big Questions to Ask Before You Choose a Home Solar Battery
For many homeowners interested in installing solar power or who’ve already embraced it, adding a battery may be the next step. Whether it’s to further lower energy bills and reduce reliance on the grid, participate in a local virtual power plant (VPP) program, or keep powering your home during unexpected power outages, batteries are becoming the “must have accessory” in solar. But understanding the differences in solar batteries is crucial to maximizing the value of your PV investment. With that in mind, here are some of the most common questions you should be asking about batteries for your home, including some bonus terms at the end to help you get acquainted!
SolarEdge’s battery for the home combined with the SolarEdge Home PV system and EV charger
What can solar and battery storage do for me?
There are many reasons to consider adding a battery to your home solar energy system:
- Backup during outages: Installing solar panels alone does not keep your lights on during a blackout. So, for many homeowners, especially those living in regions prone to grid disruptions, installing a battery with a backup interface is crucial for powering essential appliances during an outage.
- Reducing Energy Costs: By storing excess solar energy generated during the day, homeowners can save it for use at night or when electricity rates are high, therefore importing less electricity from the grid. Especially with fluctuating utility costs and more regions introducing time-of-use or dynamic electricity rates, using stored solar can lead to more long-term savings on energy bills.
- Future readiness: As residential electrification continues to expand, homeowners are increasingly relying on electricity for heating, cooling, charging their EVs and more. This places greater demands on the utility and the home. Solar systems with battery storage provide a flexible solution for managing this increased demand.
- Government Incentives and Financing Opportunities: Many regions now offer government incentives and rebates to make battery storage systems more affordable. In addition, new revenue opportunities make batteries even more financially attractive allowing utility companies to use stored energy for grid support during peak demand periods.
- Environmental Benefits: Using stored solar energy instead of grid electricity reduces your carbon footprint even further, contributing to a more sustainable and eco-friendlier lifestyle.
2. Do I want a DC-Coupled or AC-Coupled system?
AC or DC coupling refers to the way in which solar PV inverters are connected to the home’s electricity system. As solar panels produce DC energy, and batteries store DC energy, DC-coupled PV systems are more efficient for battery storage because the solar energy goes directly into the battery without needing to be converted through the inverter. In an AC-coupled solution, the energy is converted to AC through the inverter, then back to DC to store in the battery, then once again back to AC to be used in the home. With each of these conversions, some energy is lost. In a DC-coupled solution, the energy is converted only once, making the whole process much more energy efficient.
DC-coupled batteries therefore enable more energy to be stored and used. Also, energy that would otherwise be clipped can be sent directly to the battery, helping to ensure it‘s fully charged by the early evening.
3. What safety measures are employed in battery storage systems?
Like the lithium-ion batteries installed in electric vehicles, lithium-ion batteries used for home battery storage, such as the SolarEdge Home Battery should be properly commissioned and installed by a certified professional to ensure safety. Our battery solutions for homes are engineered with multiple layers of safety features to mitigate potential risks. And when everything comes from a single vendor, such as SolarEdge Home products and components, they are designed to work together seamlessly, safely, and efficiently. In addition, the SolarEdge Home Battery 400V was one of the first residential batteries to pass the strict UL9540A unit level test for fire safety hazards, allowing for indoor installations.
The SolarEdge Home Battery 400V, a lithium-ion battery, is UL9540A compliant, achieving a high certification standard for safety of energy storage systems and equipment.
4. What impacts the duration my home can run on battery backup?
The length of time a home can operate on battery backup is influenced by several factors. These include the number of batteries, the capacity of each, the power consumption of the home, and how efficiently the homeowner uses their stored energy. It's important to bear in mind that while batteries combined with backup interfaces are intended to provide electricity and keep appliances running during a grid outage, there may be limitations when it comes to powering high-energy electrical devices or large appliances for extended periods of time.
Intermittent vs. Continuous Loads
In order to understand how long a home can run on a battery or how many batteries a home needs, when homeowners are going to use their electrical loads and for how long they will be using them during an outage. Do they want to provide backup for the whole home, or just the essential loads? For this, it is important to understand the concepts of intermittent and continuous loads. Intermittent loads are electrical appliances that cycle on and off throughout the day, such as lights, stoves, fans, and HVAC systems. Continuous loads are devices that need to run continuously for the homeowner to live their daily lives. This can include Wi-Fi, refrigerators, computers - anything that needs to be running through an outage.
So, for a four- or five-person family in the U.S., having one SolarEdge Home 400V battery paired with the SolarEdge Home Backup Interface will allow them to use two or three intermittent loads and two or three continuous loads at one time for about a 10-hour period. However, it is still important to conserve energy throughout the home and be cautious when trying to run everything at once. For families who can conserve their power during an outage, one battery with backup may be enough. If they need more flexibility and more home backup capacity for extended outage protection, homeowners may want to consider installing extra batteries.
Watch the video below for more information:
5. Can I choose my battery operational preferences to better suit my needs?
- Maximize Self-consumption: By selecting this option, homeowners can harness the available solar energy from their PV system to efficiently run their homes and charge their batteries, reducing their dependence on the grid. This option is recommended for homeowners on flat-rate utility plans.
- Time-of-Use Mode: This option is most suitable for homeowners with inconsistent utility rates. This mode helps reduce energy bills by automatically charging the battery from solar and/or grid when the utility rates are low so that homeowners can use the battery to power their home when the rates are high.
- Backup Only mode: For homes with battery and a backup interface, homeowners can choose to keep their battery charged in the event of a grid outage.
More sophisticated energy management software can leverage the home’s solar energy and battery storage to create a sophisticated daily energy plan. This is becoming especially important in areas with time-of-use rates (such as California) or dynamic rates, such as some parts in the Netherlands are now introducing.
Do you speak “battery”?
Understanding the key terms associated with batteries for the home is essential to make an informed decision about which battery suits your needs. Here is a breakdown of some common home battery terms:
- Round-trip efficiency: This term is always expressed in a percentage and represents the amount of energy that can be extracted from the battery compared to the energy it was charged with. A higher round-trip efficiency indicates less energy loss, which is important for maximizing the value of your battery.
- Total capacity: Total capacity is always measured in kilowatt hours (kWh) and indicates the total amount of energy that a battery can store. The higher the total capacity, the more energy homeowners can store for longer periods.
- Battery lifespan: This refers to the duration of time a battery can effectively store and deliver energy before its performance degrades or needs to be replaced. It is typically measured in cycles or years. SolarEdge provides 10-year warranty for the SolarEdge Home Battery energy capacity that secures at least 70% energy retention over that period, when operated according to its operational manual and warranty terms.
- Battery Throughput: Battery throughput refers to the amount of energy that can be delivered by a battery over a specific period and is usually measured in watts. While lifespan emphasizes long-term durability, throughput reflects immediate performance and capacity. Both factors are crucial for evaluating the overall efficiency and reliability of the battery for the home.
- Usable energy: Usable energy represents the portion of the battery’s total capacity (usually around 80-100% of the total), that can be safely utilized without compromising the battery’s lifespan.
- Peak Power: This term is also measured in kilowatts but refers to the maximum power output that a battery can provide in a short burst of time. This is essential for managing sudden spikes in energy demand, such as turning on air-conditioners or dryers. For example, if you have a battery with a peak capacity of 7.5kW (for 10 seconds) but your jacuzzi requires 8kW to turn on, you would not be able to run your jacuzzi on a battery.
- Continuous Output Power: Continuous output power refers to the sustained power output that the battery can provide over an extended period of hours (as opposed to peak power, which might be higher but only for short bursts). It is essential to ensure that the number of batteries installed can handle the household’s energy needs. For example, the SolarEdge Home Battery 400V has a continuous output power of 5kW, meaning that the battery can consistently provide 5,000 watts of electricity to your home for an extended period.
- Backup Interface (BUI): The Backup Interface is required to enable full or partial home backup when the grid is down. Without the Backup Interface, the battery can still be used for self-consumption purposes or to connect to a Virtual Power Plant program but cannot be used in the event of a grid outage.
Transforming the future of energy with solar + storage
Solar power has made remarkable strides over the past decade, becoming one of the most affordable and widely deployed forms of renewable energy. Yet, as sunlight is intermittent, battery storage solutions combined with smart energy optimization systems hold the key to unlocking the full potential of solar by bridging the gap between the supply and demand. As we shift towards a low carbon future, more revenue streams, such as Virtual Power Plants, can benefit homeowners with battery systems. As clean energy continues to expand, solar and battery storage for the home will continue to play an important role in advancing technology and reducing our carbon footprint in an increasingly electrified world.