Vietnam has great solar energy potential, in which photovoltaic (PV) power technology is developing rapidly in Vietnam and the investors are very interested in constructing the PV power station. Building the rooftop PV power stations can save monthly electricity costs for the owners and can sell the excess electricity from the PV power station to the power grid to get the economic benefits. Solar radiation in the Northern area in general an. Vietnam has great solar energy potential, in which photovoltaic (PV) power technology is developing rapidly in Vietnam and the investors are very interested in constructing the PV power station. Building the rooftop PV power stations can save monthly electricity costs for the owners and can sell the excess electricity from the PV power station to the power grid to get the economic benefits. Solar radiation in the Northern area in general and in Hanoi city, in particular, is lower than other provinces and cities in the Central area and the Southern area in Vietnam. The development of the rooftop solar power business in Hanoi is also affected because there is no specific assessment of the potential of this kind of solar energy. In this paper, the technical potential of rooftop solar power in Hanoi city is evaluated by using high-resolution remote sensing images technology, it can be seen that the total annual installed capacity of rooftop PV power and the PV optimal in Hanoi city are about 13,169.72 MWp and 37,591,481.20 MWh/year, respectively. Otherwise, the annual operation data of a rooftop PV power station in Hanoi is also collected to evaluate the efficiency in the real working condition, it is found that the payback in the case of actual operations is about 1 year longer than the theoretical calculation.••••The solar energy potential in Hanoi city was analyzed.••A methodology for assessment of rooftop solar power technical potential has been presented.••The total installed capacity and the total generated electricity of rooftop grid-tied solar power system in Hanoi city are calculated.••The payback of the rooftop solar power station in the case of actual operation has been compared with the theoretical calculation.PhotovoltaicInverterRooftop grid-tied PV power systemTechnical potentialCurrently, renewable energy and solar power technology [1,2] are playing an important role in the contribution of meeting energy requirements and fighting climate change across the world. Rooftop solar power is rapid growth in urban areas and can help the buildings to minimize the carbon footprint, meet the electricity needs and achieve the nearly zero-energy building [3,4].The solar energy potential in Vietnam is quite good, in which the Southern area has a higher level of solar radiation than the Northern area and Hanoi city [,, ]. The total installed solar power capacity in Vietnam by 2017 was only about 8 MW, which very low in comparison with the potential for solar power in Vietnam because there was no policy of the Government to support the development of solar power. After the government approved the support policy, the development of the application of the grid-tied PV power system was very fast. According to Vietnam Electricity's data, the total installed capacity of commercial PV power projects has reached 4464 MWp by the end of June 2019, solar power accounted for 8.28% of the total installed capacity of Vietnam's power system. This capacity scale has far exceeded the expected PV power development target of 850 MWp in 2020. Otherwise, the installation of the rooftop PV power system helps to reduce greenhouse gas emissions and protect the environment. The International Energy Agency. Hanoi is the capital of Vietnam with an area of about 3,359 km2. Hanoi is also the commercial, cultural, and educational center of Northern Vietnam and is located in the central area of the Red River Delta Fig. 1. Hanoi rapidly increased in the population (4643.4 thousand in 17 years, a 46.37% increase), in socio-economic indicators from 1960 to 2013, such as the newly built-up areas of residential housing (4987 thousand m2, a 99.48% increase), industrial establishments (97092 industrial establishments, a 97.75% increase), and electricity per capita (1531 kWh/per, a 93.75% increase).World Bank selected Solargis as a provider of global solar energy data and related solar assessment services for Vietnam including Vietnam's solar energy map. According to Solargis data, it is possible to synthesize and determine that the annual solar radiation value and the annual electricity generated from solar panels in each district in Hanoi are different. As shown in Fig. 2, the annual average PV electricity output (PVOUT) of 1050 kWh/kWp/year while the annual average global horizontal irradiance (GHI) of 1329 kWh/m2/year.
