Performance Comparison and Analysis of Heating and Ventilation of Two Kinds of Roof Solar Collectors

Two roof solar collectors (RSCs), conventional single pass RSC and new double pass RSC, were compared. The new roof solar collector, which is formed by integrating a double pass solar air collector with the roof of the building, can be operated more efficiently for space heating in winter, and for natural ventilation in other seasons. To evaluate the performances of the two RSCs for both space heating and natural ventilation, a single traditional Chinese style house, on which the two RSCs will be mounted, was developed. The efficiency of solar energy conversion for the new RSC is higher than that of the single pass one by 10% on average, and the ventilation rate contributed by natural ventilation for the new RSC can be improved to a great extent for most cases, indicating that the new RSC is superior to the single pass one from the viewpoint of both space heating and natural ventilation. The new RSC is more potential for improving indoor thermal environment and energy saving of buildings.

Analyses and Simulation of V-I Characteristics for Solar Cells Based on P-N Junction

Through theoretical analyses of the Shockley equation and the difference between a practical P-N junction and its ideal model, the mathematical models of P-N junction and solar cells had been obtained. With Matlab software, the V-I characteristics of diodes and solar cells were simulated, and a computer simulation model of the solar cells based on P-N junction was also established. Based on the simulation model, the influences of solar cell’s internal resistances on open-circuit voltage and short-circuit current under certain illumination were numerically analyzed and solved. The simulation results showed that the equivalent series resistance and shunt resistance could strongly affect the V-I characteristics of solar cell, but their influence styles were different.

Solar-Assisted Space Heating and Small Pond-Assisted Space Cooling of a Highly Insulated Energy Efficient House

For three weeks in October 2009, the U.S. Department of Energy hosted the Solar Decathlon Competition in which 20 teams of college and university students competed to design, build, and operate their own version of a solar-powered house. Team North＇s mission was to deliver North House, a compelling, marketable solar powered home for people with active lifestyles, while building Canada＇s next generation of leaders in sustainable engineering, business and design. This paper deals with a solar-assisted space heating system that was studied as a potential design for the competition. Among several other conclusions, it was found that using a solar-assisted in-floor heating system can decrease the energy consumption to only 8% of the case without the in-floor loop.

Selection and Design of WSN Node Based on Solar Power in Facility Greenhouse

In this study, the green energy saving of greenhouse sensor node is de- signed to reduce the system power consumption and high efficiency. The green renewable solar energy resources are used as the energy source of nodes; the lowenergy consumed and cost effective MSP430 chip is used as the main control chip of the processor unit; the transmission frequency of the wireless transmission unit is 433 MHz, which has the characteristics of low power consumption, high signal strength, long transmission distance and small signal attenuation during the transmission; the power supply system unit is composed of monocrystalline silicon solar panel and high performance rechargeable lithium ion battery. The selection basis of each unit is clarified in detail, and optimization is performed by hardware circuit and software program to further reduce power consumption. The power consumption of the node is calculated by the experiment, and the charging conditions of the solar panel used in the node is tested. The results show that the system can achieve the setting target through the selection and design.

Potential of Photovoltaic Industry in Egypt

PV （photovoltaic） market is dominated by Europe, especially Germany and Spain. However, the PV industry leaders recently exist in Asia. The huge market growth require industry growth, but with competitive cost. The electricity shortage in Egypt makes transferring to photovoltaic technology necessary, especially with the high solar radiation. The only reason why grid parity is not yet reached in Egypt is the elevated subsidiary of conventional electricity. If this subsidy is transformed to incentives for using and manufacturing solar cells, the situation will vary. This article shows that transferring PV industry to Egypt has a potential of cost saving of 5.7%, which could be translated either into competitive price or higher return on investment. This work is not a feasibility study. However, based on the cost structure of each phase in the PV industry value chain, the benefit （5.7% cost reduction potential） of transferring the industry to Egypt is worthy to accomplish the needed feasibility study.

Net-Zero Energy Building Enhancement for a Leadership in Energy and Environmental Design Platinum Educational Facility

In the United States, university buildings use 17% of total non-residential building energy per year. According to the NREL （National Renewable Energy Laboratory）, the average lifecycle of a building in a university is 42 years with an EUI （energy use intensity） of 23 kWh/m^2/y. Current building and energy codes limit the EUI to 16 kWh/m^2/y for new school buildings; this benchmark can vary depending on climate, occupancy, and other contextual factors. Although the LEED （leadership in energy and environmental design） system provides a set of guidelines to rate sustainable buildings, studies have shown that 28%-35% of the educational LEED-rated buildings use more energy than their conventional counterparts. This paper examines the issues specific to a LEED-rated design addition to an existing university building. The forum, a lecture hall expansion of to an existing building at the University of Kansas, has been proposed as environmentally friendly and energy-efficient building addition. Comfort and health aspects have been considered in the design in order to obtain LEED platinum certificate. The forum＇s energy performance strategies include a double-skin facade to reduce energy consumption and PV （photovoltaic） panels to generate onsite energy. This study considers various scenarios to meet NZEB （net-zero energy building） criteria and maximize energy savings. The feasibility of NZE criteria is evaluated for： （a） seasonal comparison; （b） facility occupancy; （c） PV panels＇ addition in relation to double skin facade. The results of NZEB approach are compared to LEED platinum requirements, based on Rol （return on investment） and PV panel＇s efficiency for this specific educational building.

Life-Cycle Cost Analysis of an Installed Multiunit Seasonal Thermal Energy Store

The financial viability of a solar STES （seasonal thermal energy store） installed in a mixed commercial and residential multiunit development of low-energy buildings located in Lysekil, Sweden, a maritime Scandinavian Climate has been investigated. Using recorded figures for the installation costs and performance, a financial life cycle analysis has been undertaken to determine the cost effectiveness of the system. The time value of money is considered and an LCC （life cycle cost） analysis undertaken to identify the cost-effectiveness of the solution. It shows that while a direct heating and hot water system incorporating STES can be economically viable in a Swedish maritime climate in the long term, assistance such as that provided by government incentives is required to assist with the high capital cost of the initial investment.

Analysis of Energy Saving Achievable through Solar Photovoltaic Systems on School Roofs： A Case of the City of Rome

Embracing renewable energy technology makes a lot of sense for the public sectors and schools as it meets the government sustainability goals and provides a financially viable means of achieving carbon savings while offering income potential. This study is aimed to quantify the achievable energy saving by spread use ofphotovoltaic systems on public building stock in the city of Rome. The installation of PV （photovoltaic） systems in the historic center depends on the feasibility conditions, generally more complex compared to the cases examined in the consolidated city, because they require compliance with the formal and aesthetic characteristics of the buildings, so the choice must be made between compatible components, which allow to minimize the transformation. The suburbs are characterized by large plane roofs in bad conditions and belonging to isolated buildings, so the useful surface, according to shading condition, offers a big potential for renewable technologies. The research provides an evaluation of maximum production of solar energy and the subsequent energy saving and reduction of greenhouse gasses, using parametric data, and an evaluation of the cost-effectiveness, with a rough calculation of return on investment.

Effects of Latitude and Design Variables on Performance and Cost of a Solar Heating System with Seasonal Storage

A thermo-economic model for the simulation and optimization of a CSHPSS （central solar heating plant with seasonal storage） is presented. The model, written in Matlab, allows to analyze the effects of different design and operating variables on plant performance and cost. Daily and seasonal variations of solar irradiation at different latitudes are considered, and an original approximate model for thermal stratification is included. Since a limited computational time is required, the simulation model can be effectively integrated with a non-linear constrained optimization procedure so as to determine the optimal choice of design variables for different locations and operating conditions. The comparison between a two-variable and four-variable optimization for five different locations at various latitudes has been presented, showing a significant decrease in pay-back time with latitude. Finally a sensitivity analysis on the most important design and operating variables has been performed and presented. It emerges that the optimal insulator thickness always decreases with latitude. The optimal tilt angle is slightly lower than latitude only when the plant is designed to cover the whole thermal load, while higher tilt values are selected in case of partial load covering.