Off-Grid Solar Power System with Battery Storage for Remote Homes

In remote high-altitude regions, extending the power grid is prohibitively expensive, and households often rely on diesel generators for electricity. However, this solution is costly, inconvenient, and environmentally unsustainable. With the rapid development of photovoltaic and energy storage technologies, clean energy has become the most viable alternative for off-grid communities.

This design focuses on a herder household located at an altitude of 4,200 meters, where annual sunshine reaches approximately 2,600 hours and the average annual solar radiation is 5,800 MJ/m². Based on the local conditions and daily power demand, a stand-alone solar photovoltaic and battery storage system is proposed. The system is designed to provide reliable 24-hour electricity supply for lighting, household appliances, and small-scale production equipment. It combines technical feasibility, economic efficiency, and environmental sustainability, offering a practical solution to improve the quality of life for residents in remote plateau regions.

1. Project Background 

A residential settlement is located at an altitude of 4,200 meters, 35 kilometers from the nearest power grid, and the cost of extending the grid is prohibitive. The area has an average annual sunshine of approximately 2,600 hours and abundant solar resources (annual average radiation of 5,800 MJ/m²). A 24-hour off-grid power supply was required for a herder household (a family of five) to meet basic living needs, lighting, and small production equipment. 

2.Load Analysis

Key Parameters:

Total load power: ≈1.1kW.Pump is a inductive load.When it starts,peak power is about 4 times rated power.Peak power:1200W

Average daily power consumption: 1.62kWh

All the home appliances are 220V/50Hz.

3. Photovoltaic system design

3.1 PV array configuration

3.1.1 Soalr panel selection: Monocrystalline silicon photovoltaic panel (325W/piece)

● Maximum power (Pmax/W):325

● Open-circuit voltage (Voc/V)::46.15

● Short circuit current (Isc/A) :9.39

● Peak power voltage (Vmp/V) :37.45

● Peak power current (Imp/A) :8.68

● Module Efficiency:19.2%

3.1.2 Solar panel quantity calculation:

● Local average daily peak sunshine hours: 4.08 hours (based on NASA weather data)

● Total system power demand = daily power consumption / system efficiency = 1600Wh / 0.8≈ 2000Wh

● Total module power = 2000Wh ÷ 4.08h ≈ 490W

● Actual configuration: 2 × 325W = 650W (25% redundancy to account for dust, attenuation, and rainy days)

● Array layout: 2 modules in series (2S), operating voltage 65.2V

3.2  Battery Configuration

Solar battery selection: Lithium iron phosphate battery (long life, high energy density)

Capacity Calculation:

Requires operation for three consecutive rainy days (no sunlight)

Total discharge capacity : daily power consumption × number of days without sunlight × depth of discharge

 1620Wh × 3 ÷ 0.95 = 5115Wh

Total battery capacity (24V system) : 5115Wh ÷ 25.6V ≈ 200Ah

Actual configuration: one 25.6V200Ah solar battery

Actual usable capacity: 25.6 × 200×0.95 (DOD) = 4864Wh

Here we use Brovolt's 25.6V200A battery. It has high energy density, long life, high discharge rate, and a lifespan of up to ten years. Bluetooth and heating modules are optional.

3.3 Inverter Selection

Power Requirement: Water pump (300W). This is an inductive load, and the peak power at startup is approximately four times that of a 1200W load.

Model:Pure sine wave solar inverter (shock-resistant)

Rated Power: 2kW

Peak Power: 4kW

Battery Voltage: DC 24V

Output Voltage: AC 220V ±3%

Solar Charger type:MPPT

Maximum PV Array Open Circuit Voltage:102vdc

Maximum PV Array Power:1400W

MPPT Range @ Operating Voltage:30-80VDC

Maximum Solar Charge Current:50A

4. System Structure Diagram

5. Key Design Safeguards

Anti-Reverse Current Protection:

1. The battery has a built-in temperature sensor, which activates heating when the temperature drops below -10°C.

2. The photovoltaic panels are tilted at a 60° angle (a high angle in winter enhances snowfall).

 Lightning Protection:

1. The photovoltaic array grounding resistance is ≤ 4Ω.

2. A secondary lightning arrester (40kA) is installed on the DC side.

3. Overload Protection: The inverter has built-in overcurrent, short-circuit, and overtemperature protection.

6. Power Generation and Economic Analysis

6.1. Power Generation Estimation

6.2 Initial investment

6.3. Economic Benefits: 

Cost of alternative solution: Diesel generator (annual fuel consumption ≈ 600L × 1.1 USD/L = 660USD/year) 

PV system annual maintenance fee: approximately 45USD (battery testing/module cleaning) 

Static payback period:

Initial investment ÷ annual fuel savings = 1106 ÷ (660- 45)=1.8 years 

Battery life: 10 years (based on 95% DOD usage), system life > 15 years

7. Operation and Maintenance Management Recommended User Training:

1. Clean dust from the photovoltaic panel surface monthly.

2. Remote Monitoring: Install a 4G data acquisition module (to monitor power generation and battery SOC).

3. Regular Maintenance: Check battery health quarterly.

4. Check ground resistance and cable insulation.

8. Design Summary

This system, based on a 650W photovoltaic array and 5kWh energy storage, meets the off-grid power needs of a single household in the plateau region around the clock. With an initial investment of 1,106USD, the diesel engine replacement cost can be recovered in 1.8 years.

Design Features Include:

1. The inverter improves power generation efficiency by over 10% in low-temperature environments and ensures reliable starting of motor loads.

2. The lithium-ion battery supports -30°C operation, making it suitable for cold and high-altitude areas.

3. 3-day energy storage redundancy to cope with continuous rainy weather