Preface

Yunnan boasts abundant solar irradiation resources. Mountain homestays commonly suffer from grid power fluctuations, occasional blackouts and high electricity costs during peak hours. As commercial premises, homestays require stable continuous power supply for air conditioning, lighting, water supply & drainage and guest-room appliances. Once the utility grid fails, guest experience will be directly impaired and operational losses incurred. This solar-storage integrated system makes full use of local solar energy, combining photovoltaic power generation, energy storage and grid-tie/off-grid switching technology. During daytime, PV power supplies the homestay loads preferentially, and surplus electricity is stored in batteries. When sunlight is insufficient or grid power fails, the stored energy is released to sustain loads. The system supports three-phase unbalanced output and fast grid-tie/off-grid switching. It meets daily power demand and emergency backup requirements, improving power supply resilience, reducing reliance on public grids, and delivering a green and reliable power solution tailored for homestay operation.

PV Panel Installation Diagram

I. Main System Equipment Parameters

The homestay solar-storage system is scientifically configured to match site conditions and power consumption requirements. The whole system consists of photovoltaic power generation unit, inverter & control unit and energy storage unit.

30kW 96kWh Solar-Storage System Configuration Diagram

The core configuration includes 48 pieces of 630W high-efficiency PV modules, wired in standardized strings, paired with a 30kW dedicated solar-storage hybrid inverter, and matched with a total 96kWh stacked high-voltage energy storage battery. All devices feature well-matched parameters and strong coordination. Leveraging Yunnan’s superior solar resources, the system realizes integrated PV generation, energy storage and power consumption to satisfy dual demands: on-site self-consumption and backup power during grid outages.

➤ 630W PV Module

This high-efficiency N-type monocrystalline silicon PV module delivers excellent low-light power generation performance. Under STC conditions, its open-circuit voltage is 48.59V. With high mechanical strength, it withstands bidirectional wind and snow loads, suitable for outdoor installation in Yunnan. Reliable encapsulation protects against environmental corrosion, adapting to the large day-night temperature difference on plateaus. Stable electrical parameters and consistent power output allow series connection into PV strings to connect to the inverter’s MPPT ports. The anodized aluminum alloy frame facilitates mounting on brackets, and standard PV connectors simplify field wiring. Balancing generation efficiency and service life, the modules provide steady DC energy input for the whole system to meet daytime power demand of the homestay.

➤ 30kW Distributed Solar-Storage Hybrid Inverter

The 30kW solar-storage hybrid inverter supports both grid-tie and off-grid modes, with millisecond-level switching between modes to guarantee uninterrupted power supply for homestay loads. It is equipped with 2 MPPT PV input channels and supports three-phase unbalanced output, adapting to fluctuating three-phase loads of homestays. The maximum PV input voltage is 1000V, and the MPPT operating range is 180‑850V, compatible with high-voltage energy storage batteries. Rated grid-tie output is 30kW; rated off-grid output is 30kW, and hybrid combined output can reach 130kW. It adopts air-cooled automatic temperature control and comprehensive protection logic, meeting industrial and commercial standards for protection and electrical performance.

Cloud remote monitoring is supported to implement peak-valley power management. It coordinates energy scheduling among PV, battery and utility grid, converts AC/DC power, and manages energy flow of the entire system.

➤ 96kWh Rack-mounted High-voltage Energy Storage Battery Pack

The 96kWh rack-stacked lithium iron phosphate energy storage system is assembled by 6 ×16kWh units connected in series, with nominal voltage of 51.2V. Equipped with BMS intelligent management system, it realizes active equalization, overvoltage, overcurrent and temperature protection. Multiple units can be paralleled for capacity expansion. Its communication protocol is compatible with the inverter in this project, enabling real-time exchange of SOC, voltage and current data. The battery enjoys outstanding cycle life, over 8000 cycles at 80% DOD, with a wide charge-discharge temperature range to adapt to plateau temperature variations in Yunnan. The rack design allows indoor cabinet stacking installation, with status indicators; battery operating status can be checked via APP. The recommended discharge depth is 90%. It stores surplus PV electricity generated in daytime and releases power at night, on cloudy days or during grid faults to provide continuous backup power for the homestay.

II. Electrical Matching Verification of PV Strings

30kW 96kWh Solar-Storage System Topology Diagram

This project adopts 48 pieces of 630W PV modules. 12 modules are connected in series to form one string, with a total of 4 strings. Two strings are paralleled into one circuit; two circuits are separately connected to the two MPPT ports of the inverter.

The open-circuit voltage of one module is 48.59V. One string with 12 modules in series reaches 583.08V, fully falling within the inverter MPPT operating voltage range of 180–850V. Voltage matching is good with no risks of overvoltage or undervoltage operation. The working current of a single module is 14.92A. After two strings are paralleled, the input current per circuit is 29.84A, lower than the inverter single-channel MPPT maximum input limit of 40A. The current condition is safe and compliant.

Total installed PV capacity is 30.24kW. The system daily power generation reaches 151 kWh, with 96 kWh surplus electricity stored in the battery. Reasonable string layout ensures fully matched electrical parameters with the inverter, enabling stable long-term safe power generation and energy storage.

III. System Operating Principle

The whole solar-storage system consists of PV generation unit, inverter & control unit, energy storage unit, homestay loads and utility grid, forming a fully automatic intelligent energy dispatching system.

Video: Working Principle Demonstration of 30kW 96kWh Solar-Storage System

When sunlight is sufficient in daytime, PV modules produce DC power, collected via the inverter MPPT ports and converted into AC power to preferentially supply all homestay loads including lighting, air conditioning, kitchen equipment and water supply. When PV output exceeds real-time homestay consumption, surplus power is automatically stored in the 96kWh battery.

At night or on cloudy days with insufficient PV generation, the system automatically draws power from the battery. When the utility grid is normal, the system runs in grid-tie mode for self-consumption with surplus power stored. Once grid power cuts off, the inverter switches to off-grid mode within milliseconds. PV plus battery jointly power loads to ensure uninterrupted supply. After grid recovery, it automatically switches back to grid-tie mode without manual intervention.

IV. Available Load Power & Power Supply Duration

The system rated off-grid output power is 30kW, capable of covering all homestay loads: full-house lighting, central air conditioning, water heaters, water supply & drainage, guest-room smart appliances and monitoring devices. Calculated at the safe discharge depth of 90%, the usable capacity of the energy storage system is 86.4kWh. The actual backup duration is shown below:

• Half load at 15kW: continuous power supply for approx. 5.7 hours
• Basic load at 8kW (lighting + domestic equipment): continuous power supply for approx. 10.8 hours
• Emergency load at 3kW (lighting + monitoring): continuous power supply up to 28.8 hours

Actual runtime will slightly fluctuate subject to real-time PV recharge, ambient temperature and equipment losses.

Conclusion

This Yunnan homestay solar-storage system is configured to match local solar resources and homestay power consumption. Equipment parameters are well-matched and string design is safe and compliant. With daily generation of 151 kWh and 96kWh storage capacity, it effectively offsets grid electricity and reduces power expenses for the homestay. Supporting grid-tie self-consumption and off-grid emergency backup, it resolves unstable mountain grid supply and sudden blackouts, guaranteeing continuous power for homestay operation. Featuring long service life, high stability and easy maintenance, this green energy solution balances economic benefit and practicality, fully suitable for long-term homestay operation.