Calculate how many Tesla Powerwalls or equivalent units you need for your energy storage requirements. Enter your capacity need to find the number of units.
Home battery storage systems like the Tesla Powerwall come in fixed-size modules that can be stacked. The Tesla Powerwall 2 provides 13.5 kWh of usable capacity and 5 kW of continuous power (7 kW peak). Other popular options include the Enphase IQ Battery (3.36 or 10.08 kWh) and the LG RESU (9.6 or 16 kWh).
Determining how many units you need depends on your energy storage requirement (in kWh) and your power requirement (in kW). A home that needs 25 kWh of storage and 7 kW of continuous power would need two Powerwalls (27 kWh, 10 kW).
This calculator lets you enter your required storage capacity and the unit capacity of your chosen battery to quickly determine how many modules to buy. It rounds up since you can't buy fractional units.
Precise measurement of this value supports sustainable energy planning and helps organizations reduce their environmental impact while maintaining operational performance and comfort levels.
Battery manufacturers sell fixed-size modules. This calculator instantly tells you how many modules meet your storage and power needs without manual math. Having accurate metrics readily available streamlines utility bill analysis, budget forecasting, and investment planning for energy efficiency projects and renewable energy installations. Consistent measurement creates a reliable baseline for tracking energy efficiency improvements and validating the impact of conservation measures and equipment upgrades over time.
Units Required = ⌈ Required kWh / Unit kWh ⌉ (rounded up) Total Capacity = Units × Unit kWh Total Power = Units × Unit kW
Result: 2 units (27.0 kWh, 10.0 kW)
25 kWh / 13.5 kWh per unit = 1.85, rounded up to 2 units. Total capacity: 2 × 13.5 = 27.0 kWh. Total continuous power: 2 × 5 = 10.0 kW. This provides 2 kWh of headroom beyond the requirement.
Capacity (kWh) determines how long the battery lasts. Power (kW) determines how many appliances it can run simultaneously. You may need extra units for power even if one unit covers your capacity needs. For example, running a 5 kW air conditioner requires at least one Powerwall just for that load.
Tesla Powerwall 2: 13.5 kWh, 5/7 kW. Enphase IQ Battery 10: 10.08 kWh, 3.84 kW. LG RESU 16H Prime: 16 kWh, 7 kW. Franklin WH: 13.6 kWh, 5 kW. Each offers different tradeoffs between capacity, power, warranty, and price per kWh.
Multiple battery units require adequate wall space, proper ventilation, and a main panel upgrade in some cases. Indoor installation is preferred for temperature management. Check local codes for battery placement requirements.
A Tesla Powerwall costs approximately $8,500–$11,500 installed (before incentives). The per-unit cost may decrease slightly when installing multiple units. The 30% federal ITC applies to batteries installed with solar, reducing the net cost significantly.
Generally, no. Battery systems need matched voltage, communication protocols, and charge controllers. Mixing brands can cause compatibility issues and void warranties. Choose one brand and stack identical units.
Most homes need 2–3 Powerwalls for whole-home backup during an outage. This provides 27–40.5 kWh of storage and 10–15 kW of continuous power. Homes with electric heating, EV charging, or pools may need 3–4 units.
Popular alternatives include the Enphase IQ Battery 5P (5 kWh modular), LG RESU Prime (16 kWh), SonnenCore (10 kWh), Franklin WH (13.6 kWh), and Generac PWRcell (9–18 kWh). Each has different power ratings, cycle warranties, and pricing.
Batteries are optional for grid-tied solar. Net metering provides credit for excess production without batteries. Batteries add value for outage protection, time-of-use rate optimization, or areas with poor net metering rates.
Duration depends on your consumption rate. A 13.5 kWh Powerwall running essential loads (lights, fridge, router) at 0.5–1 kW lasts 13–27 hours. Running the whole home at 3–5 kW, it lasts only 2.7–4.5 hours. Multiple units extend the duration linearly.