solar energy storage systems for home

P Peter Lu Energy Storage Product Manager, GreenMore A stackable battery is a home energy storage system built from separate modules that sit on top of each other. Instead of replacing a 5 kWh unit with a 10 kWh one when your needs grow, you add another module of the same type. The modules share a common base, communicate over a single bus, and appear to the inverter as one larger battery. This modular approach is why stackable systems are popular with homeowners who want to start small and add capacity over time. How stackable batteries work Each module contains its own cells and a battery management system that monitors voltage, current and temperature inside that module. The modules are linked in parallel on a common DC bus so the combined capacity adds up, while the inverter sees the stack as one battery. Communication with the inverter runs over CAN, RS485 or a vendor-specific protocol, and the bus master (usually the first module) reports the state of charge for the whole stack. Because the modules share a design, they age together and the BMS can balance them as a group, which is simpler than trying to mix different generations. Why choose a stackable design The main benefit is staged investment. A household that only needs a few hours of evening backup can begin with two modules and add more when an electric vehicle arrives or when the solar array is expanded. A stackable system also reduces waste: a failed module can often be replaced without scrapping the whole unit, and the same hardware can be moved if the home is relocated. The trade-off is that the system is tied to one product family — you cannot typically add a competitor's module, and the manufacturer's stated maximum stack size is a real limit, not a suggestion. GreenMore stacked modular energy storage battery What to check before buying Capacity per module and maximum stack size. The module size sets the step at which you can add capacity, and the maximum stack size sets the ceiling. If the largest stack is still too small for your long-term plan, a stackable design will not solve it. Inverter compatibility. Confirm the inverter you are using (or plan to use) is listed as compatible with the specific battery model. CAN on the label does not mean it will communicate; the protocol and firmware version both matter. Usable versus nominal capacity. Two systems with the same headline kWh can deliver different energy to the wall because of different depth-of-discharge limits and efficiency. Size from usable capacity. Safety and certification. Ask for the documents relevant to your market, such as CE and IEC, plus UN38.3 and MSDS for transport. Verify the certificate rather than relying on a logo. GreenMore covers non-tile storage components for 3 years. Physical fit and weight. A four-module stack is heavier than a single wall unit. Confirm the floor or wall can take the load, and that there is clearance for ventilation and future modules. Where stackable batteries fit Stackable batteries are a good match for homes that plan to grow: a small solar array now with a larger one later, a current combustion car that will be replaced by an electric vehicle, or a household that is adding a heat pump. They are less compelling for homes that already know exactly how much storage they need and will never change — in that case a single larger wall or rack unit may be simpler and sometimes cheaper per kWh. They are also not the right answer for utility-scale projects, where containerized battery cabinets with a separate PCS are the norm. GreenMore's customizable stackable energy storage batteries You can see our residential range on the home energy storage category page. If you want to work through whether a stackable system fits your load profile and future plans, use the contact page and share your current bill, expected new loads and whether you have or plan solar. FAQ Can I mix old and new modules in the same stack? In principle yes, if they are the same model and generation from the same manufacturer. Mixing different chemistries, voltages or BMS generations is usually not supported and can cause the pack to limit itself to the weakest module. How many modules can I stack? The limit is set by the manufacturer for each model, based on the BMS, bus current and inverter rating. Exceeding it is not safe. Ask for the datasheet and check the stated maximum before planning expansion. Is stackable better than a wall-mounted battery? Neither is universally better. Wall-mounted units save floor space and are cleaner for small capacities. Stackable systems scale more cleanly when you expect to add capacity. The choice depends on how much storage you need now, how much you may need later and where the unit will live in the home. Does adding a module void the warranty? Not if it is the same model added within the manufacturer's stated limit and installed per the guide. Adding a third-party module or exceeding the maximum stack size typically does void it. Confirm this in writing before buying. P Written by Peter Lu — Energy Storage Product Manager, GreenMore Peter works with distributors, installers and system integrators to size residential and commercial storage around real load profiles. He focuses on LiFePO4 systems that match the inverter, grid rules and backup needs of each destination market.

P Peter Lu Energy Storage Product Manager, GreenMore There is no single correct battery size for every home. A system that is too small runs out during the evening or a long outage; one that is too large costs more than it will ever save. The right number comes from three things: how much electricity the loads you care about actually use, how long you want them to run without the grid, and how much of that energy the battery can realistically deliver. This guide walks through all three and ends with a simple worked example. Step 1: Build your load profile Start from your electricity bill, which states daily or monthly kilowatt-hours, rather than guessing from a list of appliances. Then separate the loads you want to keep running during an outage or overnight from the ones you can do without. Refrigeration, lighting, internet, a fan or a small heat-pump circuit usually make the essential list; an electric oven, clothes dryer or whole-house air conditioning often do not. To make this concrete, read the nameplate power of each essential appliance and multiply by the hours it runs per day. A 150 W refrigerator cycling for 8 hours, for example, uses about 1.2 kWh. Add the essential loads together to get your daily critical load. A small efficient home might land near 5 kWh, a typical family home around 10 to 15 kWh, and a large home with electric heating considerably more. If your main goal is savings rather than backup, also check your utility's time-of-use schedule. Under a plan with a clear peak and off-peak gap, the battery should be large enough to shift a meaningful share of your evening consumption; where rates are flat all day, size mainly for backup and solar self-consumption. Treat any quoted prices as illustrative — tariffs differ by utility and change over time, so use your own plan. Step 2: Decide your backup target Next, decide how long the essential loads must run on their own. Most homes aim to cover one evening and night until solar returns, which is effectively a one-day target. Off-grid and weak-grid homes may want two days or more to ride through cloudy weather. Backup days multiply the energy you need, so this single decision has the biggest effect on cost. Basic backup — lights, refrigerator and communications for a short outage; roughly 3 to 5 kWh of usable energy. Comfort backup — adds heating or cooling, a water heater and kitchen circuits; commonly 8 to 15 kWh. Whole-house or off-grid — running the full home for a day or more; usually 20 kWh upward and often a generator for long stretches. Step 3: Apply depth of discharge and efficiency You cannot use 100% of a battery's nameplate capacity repeatedly without shortening its life. The usable share is set by the recommended depth of discharge (DoD), and some energy is lost in the inverter, cabling and battery itself. Lithium iron phosphate (LiFePO4) systems commonly allow about 90% DoD and run at a round-trip efficiency near 90%, but the exact figures come from the product datasheet, and it is sensible to leave a small margin rather than cycle at the limit every day. Battery capacity (kWh) = daily critical load × backup days ÷ (DoD × system efficiency) Worked example Suppose the essential loads total 12 kWh per day. For one night of backup with a DoD of 0.9 and efficiency of 0.9: 12 × 1 ÷ (0.9 × 0.9) ≈ 14.8 kWh Rounding up leaves headroom, so a system around 15 to 20 kWh fits a one-night target. If the same home wanted two days of autonomy, the requirement doubles to about 30 kWh — a decision worth comparing against adding a backup generator, which is cheaper for rare multi-day events. Note the distinction between nominal and usable capacity: a battery sold as a certain kWh delivers less to the wall, so always size from usable energy. Home situation Typical usable capacity Configuration Apartment or small house, short outages 5 to 10 kWh Single wall-mounted battery, single phase Family home, one-night backup 10 to 20 kWh Wall or stacked system, hybrid inverter Large home or villa, three-phase loads 20 to 30 kWh Stacked modules, three-phase inverter Off-grid or two-day autonomy 30 kWh+ Multiple modules, often with a generator Leave room to grow A modular battery lets you add capacity later, but only if the inverter and communication bus support it. It is common to start with enough storage for the essentials, add modules when an electric vehicle or heat pump arrives, and integrate solar on the same system. Confirm the expansion limit and that new modules are compatible before buying; not every wall-mounted battery can be extended, and mixing different generations can be restricted. GreenMore energy storage batteries support parallel expansion of up to 15 units What to check before you buy Match the battery and inverter. Their voltage windows, power rating and control protocol must be compatible. A battery is only as useful as the inverter it pairs with, so confirm the combination works rather than buying them separately on price. Check real certifications. Ask for the documents relevant to your market, such as CE and IEC for many regions, plus UN38.3 and MSDS for transport and handling. Safety testing such as IEC 62619 is a good sign; verify the certificate rather than relying on a logo. Compare usable capacity and warranty, not sticker size. Two batteries with the same nominal kWh can differ in usable energy, cycle life and warranty terms. Read the cycle definition and warranty period — GreenMore covers non-tile storage components for 3 years. Avoid undersizing on price. A battery that is regularly flattened or pushed past its limits will not reach its rated life. If budget is tight, protect the essential loads and expand later rather than running a small unit at its limit. You can see the residential range on our home energy storage category page and the home energy storage system product page. If you send us your bill, appliance list, country and backup target, we can work through the sizing with you — use the contact page or email export@gmsolarkit.com. FAQ Is a 5 kWh battery enough for a house? For a small efficient home that only needs to keep lights, a refrigerator and internet through a short outage, around 5 kWh of usable storage can be enough. It will not run heating, cooling or the whole home overnight, and it is tight where outages last more than a few hours. What is the most common home battery size? Most grid-connected family homes land between 10 and 20 kWh of usable capacity, which covers the essential loads through one night. The right point within that range depends on your evening consumption, whether you heat with electricity and how long local outages tend to last. Should I use nominal or usable capacity when sizing? Use usable capacity. Nominal capacity is the battery's full rating; usable capacity is what remains after the DoD and efficiency limits. A 12 kWh nominal battery might deliver around 10 kWh to your appliances, so sizing from usable energy avoids coming up short. Is it cheaper to add a battery or a generator for long outages? For frequent short outages and daily savings, a battery is clean, quiet and automatic. For rare multi-day events, a generator — or a hybrid system that uses a battery first and a generator for extended bad weather — usually costs less than buying enough storage for several days of autonomy. P Written by Peter Lu — Energy Storage Product Manager, GreenMore Peter works with distributors, installers and system integrators to size residential and commercial storage around real load profiles. He focuses on LiFePO4 systems that match the inverter, grid rules and backup needs of each destination market.