In this century development, some African countries are now still facing a challenge of lack of electricity, because hydropower and thermal fuel are still on a small scale. This problem results in less economic productivity decline of some countries like Rwanda which is among African countries that are at a very high speed in development, and the grid lines are few compared to the need for electricity, especially in rural areas whereby each household needs power usage instead of using local and traditional means of ironing and lighting at home. This issue can be solved using Renewable Energy for rural electrification such as Photovoltaic systems. Therefore, this paper reviews Solar Energy for Sustainable Urban Development in Rural Area (Rwanda). Under this work, case study result will focus on one village in Rwanda named as" Agahozo-Shalom Youth Village (ASYV) located in Rwamagana district in Eastern Rwanda. The project is the first utility-scale, grid-connected, commercial solar field in East Africa. The field is 8.5 MW of grid-connected power to 15,000 homes and it increased Rwanda's generation capacity by 6%. Solar urban design is a phase of sustainable urban planning that will facilitate development and could provide new solutions to the world's energy problem by reducing its consumption and improving the performance of future buildings. The main mission of this article is to care for Rwanda's most vulnerable children, is leasing land to house the solar facility, and the fees from which will help pay for a portion of the Village's charitable.

A laboratory-scale evacuated tube solar collector (ETSCs) has been developed and tested for unloading conditions in Lanzhou, China. clear sky and cloudy conditions have been tested. Heat is generally considered instantaneous because it is a function of multiple instantaneous factors, like ambient temperature and solar radiation. The results show a clear sky day with a maximum and average value of ambient temperature, outlet, inlet, and solar radiation of 12 and -60C, 56 and 310C, 69 and 340C, 931 and 576W/m2, respectively, while a cloudy day was eight and -30C and 861.2 and 449W/m2 respectively. Clear sky day maximum and the average mass flow rate was 0.25 and 0.21 Kg/sec, while the cloudy flow rate was 0.27 and 0.03 Kg/sec, respectively. A clear sky has a heat loss of -0.307 and -0.05kW for a cloudy day. R square were 0.76 and 0.4 for clear sky and cloudy day, respectively. For the heat and radiation correlation relationship, a clear sky has a slope of 0.0029 and 0.0539 for a cloudy day. In other conditions, the solar radiation per unit area increases by 1 W/m2, and the daily heat is collected. Increasing A W/m2, the temperature difference between the average temperature of the hot water storage tank and the average temperature of the environment increases by one °C, and the daily heat collection decreases A W/m2. It concludes that a clear sky has much better efficiency than a cloudy day.

This article aims to investigate the effect of inertia on the outlet temperature of an evacuated tube solar collector. The experiments were conducted during a 24h period in Minquin County (latitude 38034’N, Longitude 10303’E). An analysis was made to determine whether the evacuated tube solar collectors’ fluid thermal inertia impacts the water storage tank temperature. The results showed differences between the useful energy delivered to the water storage tank in the case with mass flow rate adjusted depending on the incident solar radiation for the entire two days in which experiments were conducted. Two days of cloud and sunshine were considered. An indirect optimal control technique refers to the impacts of the inertia of water on the outlet collector temperature, the on/off control of the pump, and the useful heat gain from the storage tank. During days with clear sky, the average solar radiation, mass flow rate, outlet, and tank temperature were 640.02W/m2, 0.06kg/s, 290C, and 44.240C, respectively. For cloudy day was 449W/m2, 0.02kg/s, 270C and 420C respectively. The control system is provided to run the heating circulating pump after rest for several minutes to facilitate the exhaust system, then continues to run for a cycle. The DTP,ON and DTP, OFF range from 30C to 100C and from 0.20C to 1.50C, respectively.