Study on accurate regulation of power consumption in self-supporting time of off-grid system in Haikou

Abstract

In practical engineering, Off-grid PV systems have failed to meet user requirements due to the absence of precise local weather parameters and unverified battery charging times. In this study, off-grid solar street lights in a village in Haikou were taken as an example. A three-year monitoring period was conducted using a local PV station. It was observed that in this area, the lowest solar radiation is typically recorded from December to January. Over three years, there were four instances of continuous overcast and rainy weather, with the longest period lasting up to 9 days. During these 9 days, the daily average power generation per kilowatt of PV module fluctuated between 0.46 and 0.92 kW. Based on this data, a theoretical formula for the optimal daily power consumption was derived, and it was determined that 180W and 240W were the optimal power consumption levels for continuous overcast and rainy weather. The charging time for the batteries was verified to be 4 days. Finally, practical validation was conducted using the village's solar street lights, confirming that the optimal power consumption during continuous overcast and rainy days was 180W, and during continuous overcast days, it was 230W. These research findings hold significant importance.

Highlights

Through theory and demonstration, it is concluded that:

1. Based on years of meteorological monitoring, it has been determined that the maximum self-sufficient duration for the off-grid power station system in the Haikou area is 9 days.

2. Under the condition of satisfying SST, the formula of optimal daily power consumption of off-grid PV system load and optimal days of battery full charge is derived through theoretical analysis.

3. The actual engineering demonstration shows that the optimal daily consumption power of the street light off-grid system is about 180W when the load is in continuous rainy days. Under continuous overcast conditions, the optimal daily consumption power of the load is about 240 W. The best time for a fully charged battery is four days.

KEYWORDS:

• Energy and power engineering
• off-grid power station
• number of days of self-sufficiency
• accumulator capacity
• depth of discharge
• interval coefficient

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data generated or analyzed during this study are included in this published article.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by Hainan Provincial Natural Science Foundation of China: [Grant Number 121MS059].