# Regional Adaptability Analysis of Solar Roof Utilization Technologies in China
## 1 Introduction
[PERSON] [19] proposed a solar heating systems coupled with an electromagnetic heating unit and a phase change energy storage tank and established the simulation model with life cycle cost as the objective function. The economic analysis of solar technology as building energy supply has been brought forward in recent years. [PERSON] [20] presented a techno-economic investigation to analyze the economic viability of a photovoltaic battery (PVB) system in Switzerland for the years 2020-2050 using a static investment model. [PERSON] [21] developed a quantitative optimized model for analyzing the opportunities of centralized systems to adequately meet the demands of a residential neighborhood and support the grid. [PERSON] [22] presented an economic analysis of grid-connected residential rooftop PVs in Turkey. [PERSON] [23] compared the building energy consumption and carried out the photovoltaic economic analysis between residential buildings in Santiago de Chile and Santo Domingo of the Dominican Republic. The methodology considered thermal simulation, sizing of a solar PV system, an economic analysis, and CO\({}_{2}\) emissions given the solar resources of both countries. [PERSON] [24] constructed a model with economic measures of internal rate of return and payback period based on discounted cash flow to make a complete economic assessment of residential PV systems at the county level. [PERSON] [25] took the approach of analyzing various scenarios for the installation of PV roof systems in existing and future households of Cyprus island until 2050. The results showed that the electricity demand of the domestic sector can be 100% covered when over 70% of the existing residential stock installed 3 kW roof PV systems. Several other researchers have been engaged in the relevant studies, focusing on large-scale applications [26], the viability and implementation of PV battery systems [27; 28], and environmental issues of distributed PV systems [29]. The utilizations of solar energy has developed well in China. In 2018, the installed capacity of solar water heaters in China reached around 35.43 million m\({}^{2}\)[30]. The solar heating systems are mainly for domestic hot water supply (80%), space heating (14%), and other purposes (6%). There is a fast R&D development in the field of PV systems. The efficiency of a commercial c-Si PV cell is typically 14%-20%, while for a monocrystalline cell, it is between 16% and 20%, and for a multi-crystalline cell, it is typically between 14% and 16%. In 2018, the installed capacity of solar PV reached 174.45 GW [31]. With a large amount of building rooftops and a fast development of solar utilization technologies, the available solar energy resource on building rooftops could be exploited to cover a significant share of the energy demand of buildings, consequently decreasing the CO\({}_{2}\) emission of buildings [32; 33; 34]. China has a vast territory, where there are a variety of thermal climate zones. Although a series of research studies have examined the utilization of solar energy on individual buildings, these studies focus on individual climatic zones. Few have been able to evaluate the suitability of the different solar roof utilization technologies for different climatic zones of China; consequently, there is a lack of a systematic investigation and an overall estimation of the influence of climates and building types on the solar roof utilization technologies. This paper aims to fill the gaps by analyzing the regional adaptability of solar roof utilization technologies for different buildings in China. All provinces and cities in China are divided into 13 zones based on its economic development, thermal climate division, and availability of solar energy resources. Over 100 buildings are investigated, and the information of 28 buildings is analyzed to identify 18 typical building types. A new evaluation method is developed for both solar heating systems and solar PV.