This solution is an off-grid integrated PV energy storage power supply system specially customized for residential buildings, applicable to daily energy-saving power consumption and emergency backup during unexpected blackouts.

The system adopts a complete architecture consisting of photovoltaic power generation, energy dispatching via MPPT hybrid inverter, and energy storage through wall-mounted lithium iron phosphate batteries. It realizes self-consumption of solar power and surplus energy storage. It can independently and stably supply power in areas without utility grid, and realize dual-source complementary power supply when grid power is available, meeting dual demands of household energy cost reduction and power failure guarantee.

The whole system is composed of three core units: PV array, 4.2kW PV hybrid inverter and 25.6V wall-mounted energy storage battery. All electrical parameters of equipment are matched and verified, with fully compatible voltage, power and communication protocols, ensuring long-term stable and reliable operation, suitable for installation in ordinary urban and rural residential buildings across China.

The PV array of this system consists of 6 pieces of 620W N-type TOPCon monocrystalline PV modules. Key parameters under standard test conditions for a single module: open-circuit voltage Voc=50.3V, maximum power point voltage Vmp=41.6V, peak power 620W. The module reaches IP68 protection rating, capable of outdoor exposure against rain, snow and sand dust, with operating temperature range of -40℃ ~ 70℃ and excellent environmental adaptability.

The array adopts a 6-module series wiring scheme, with key electrical parameters calculated as follows:

• Total open-circuit voltage of PV array: 50.3V × 6 = 301.8V
• Maximum power operating voltage of PV array: 41.6V × 6 = 249.6V

The MPPT voltage operating range of matching SW4200T-24L Pro hybrid inverter is 60VDC ~ 500VDC. The array open-circuit voltage 301.8V and operating voltage 249.6V after series connection fall entirely within the safe MPPT tracking range of the inverter. There will be neither low voltage leading to reduced charging efficiency nor overvoltage risk of equipment breakdown, achieving excellent PV charging adaptability.

Total peak power of PV array = 620W × 6 = 3720W. The maximum PV input power of SW4200T-24L Pro inverter reaches 6200W, meaning the total PV power is far below the equipment bearing limit, reserving sufficient power margin for later PV capacity expansion. The maximum system withstand voltage of each module is 1500VDC, rated short-circuit current 15.94A, matched with special 30A fuses to provide ample safety margin for circuits.

The core power conversion equipment of this solution is the single-phase 24V SW4200T-24L Pro hybrid inverter, integrating MPPT PV charging, grid complementary charging and DC-to-AC inverter output functions. The all-in-one design simplifies system wiring and reduces fault points.

Rated AC output: 4200VA/4200W; instantaneous surge power 8400VA. It can stably drive inductive loads such as refrigerators, air conditioners and water pumps, as well as capacitive loads including TVs, computers and lighting. It outputs standard 220V pure sine wave AC power without damaging precision household electronic devices.

The equipment natively supports 24V lithium batteries and lead-acid batteries, with built-in lithium battery activation program. It communicates in real time with the battery BMS via RS485 bus to synchronously collect cell voltage, temperature and remaining capacity data. It supports dual charging via PV and utility grid, with maximum charging current up to 120A for both PV and grid charging, delivering fast charging speed.

Two switching speeds are available for power supply between grid, PV and battery: 10ms switching for precision electronic loads and 20ms for ordinary home appliances. Lights won’t flicker and household appliances won’t shut down during switching.

The unit is equipped with complete protection logic: 5-second overload protection, 10-second heavy overload protection, plus multi-level protection against overcharge, overdischarge, short circuit and overtemperature. Operating temperature range: -10℃ ~ 55℃, IP21 protection rating, suitable for stable indoor operation in storage rooms and equipment rooms. An optional WIFI module supports remote data monitoring, with a color screen and RGB status indicator lights for intuitive local maintenance.

The energy storage unit adopts 25.6V 200Ah wall-mounted lithium iron phosphate battery, with rated energy capacity of 5120Wh (5.12kWh), perfectly matching the 24V voltage system of SW4200T-24L Pro inverter.

Continuous charge and discharge current of the battery ranges from 0 to 150A, with cycle life ≥6000 times, slow capacity attenuation during long-term use and service life over 10 years. It is equipped with multi-standard communication interfaces including RS232, RS485 and CAN to realize two-way data interaction with the hybrid inverter, supporting synchronization of BMS fault alarms to the inverter display.

Built-in intelligent balanced BMS management system delivers full-dimensional cell protection against overvoltage, undervoltage, overload, short circuit and overtemperature, eliminating risks of battery swelling and thermal runaway. Operating temperature range: -20℃ ~ 60℃. Wall-mounted indoor installation saves floor space with flexible layout. The system daily storage capacity is designed as 5kWh, matching the rated battery capacity to fully store surplus PV power generated in daytime and avoid waste of solar energy. An optional APP module allows users to remotely check battery SOC and charge-discharge status via mobile phones.

The whole system adopts a three-layer safety protection system from PV input terminal, power conversion equipment to energy storage battery terminal:

1. PV modules feature insulation and leakage-proof design, matched with special DC fuses for circuits.
2. SW4200T-24L Pro hybrid inverter integrates hardware protection against overload, short circuit and overtemperature.
3. Energy storage battery is equipped with independent BMS cell protection board to monitor the status of each cell string in real time and cut off the circuit immediately upon abnormality.

The system operates without waste gas, noise or pollutant emissions, belonging to clean energy power supply solutions. Equipment operating temperature adapts to high temperature in southern summer and low temperature in northern winter, and can run stably under 5%~95% non-condensing humidity in high-humidity environments all year round.

All equipment adopts standardized modular design, facilitating simple later maintenance and component replacement with low operation threshold.

All equipment of this residential PV storage system undergoes precise calculation and matching on voltage, power and communication protocols. The total open-circuit voltage of 6 series-connected 620W PV modules is 301.8V, located within the safe MPPT operating range of SW4200T-24L Pro inverter, eliminating risks of electrical matching faults such as overvoltage and undervoltage.

The system generates around 18.6 kWh solar power per day, with 5 kWh surplus energy stored in the battery every day. It can not only reduce daily grid electricity expenses, but also provide stable emergency power when the grid is cut off, satisfying dual demands of energy saving and backup power supply for ordinary families.

With concise architecture, strong equipment compatibility, complete safety protection and convenient operation & maintenance, this complete solution serves as an economical, stable and reliable integrated off-grid PV energy storage solution for residential use.