Thermic diode solar panels for space heating

Thermic diode solar panels are a new method of heating buildings using solar energy. Each panel combines all the necessary elements of a complete solar energy system (collector, controls, storage heat exchangers and ducting) into a single module. They have no moving parts and they need no external power. Panal operation is discussed and thermic panels are compared to other typical solar heating systems: air heating, water heating, active and passive. Residential and commercial applications are also discussed.

The performance of thermic panels are compared to conventional solar systems. A computer simulation of thermic panels in a residential space-heating application resulted in predictions of the percentage of solar heat provided by the panels. The predictions are compared to similar analyses of conventional solar systems. Thermic panels did as well or better than conventional systems in the six climate types investigated. However, since their installed cost is less, they are expected to be more economic than conventional solar systems.

Thermic panels improve the economics of flat-plate collectors by their modularity and simplicity. Modularity reduces installation costs and raw materials cost; simplicity reduces maintenance costs. Furthermore, the panels can be integrated into the buildings structure, saving the cost of the wall or roof elements they replace.     

An applied methodology for assessment of the sustainability of biomass district heating systems

In order to maximise the share of biomass in the energy supplying system, the designers should adopt the appropriate changes to the traditional systems and become more familiar with the design details of the biomass heating systems. The aim of this study is to present the development of methodology and its associated implementation in software that is useful for the design of biomass thermal conversion systems linked with district heating (DH) systems, taking into consideration the types of building structures and urban settlement layout around the plant. The methodology is based on a completely parametric logic, providing an impact assessment of variations in one or more technical and/or economic parameters and thus, facilitating a quick conclusion on the viability of this particular energy system. The essential energy parameters are presented and discussed for the design of biomass power and heat production system which are in connection with DH network, as well as for its environmental and economic evaluation (i.e. selectivity and viability of the relevant investment). Emphasis has been placed upon the technical parameters of biomass logistics, energy system's design, the economic details of the selected technology (integrated cogeneration combined cycle or direct combustion boiler), the DH network and peripheral equipment (thermal substations) and the greenhouse gas emissions. The purpose of this implementation is the assessment of the pertinent investment financial viability taking into account the available biomass feedstock, the economical and market conditions, and the capital/operating costs. As long as biomass resources (forest wood and cultivation products) are available and close to the settlement, disposal and transportation costs of biomass, remain low assuring the sustainability of such energy systems.     

家用太阳热水器与太阳热水系统的技术经济比较

分析了户用太阳热水器和太阳热水系统工程的经济技术特点,对两者成本构成、项目财务净现值、投入回收期和财务内部收益率等有关指标进行了经济技术比较.分析比较表明,太阳热水系统与家用热水器相比,节省安装占地,与建筑相结合得好,在降低成本,缩短投资回收期,提高经济效益方面有明显的优势.     

Cost of house heating with solar energy

There has long been a need for a practical method of predicting the true cost of heating a house with solar energy and designing the heating system (solar and auxiliary) to achieve the minimum total annual heating cost possible under the particular climatic, geographic, and residential characteristics involved. Rough approximations based on various types of averaged values of weather and seasonal variables have previously been developed, but the reliability of such methods and results is open to question. The authors have therefore made a rigorous analysis of projected solar heating costs in eight U.S. cities and have optimized the heating system design in each location.The analysis involved the use of a high speed computer and approximately 400,000 hourly observations in eight cities of radiation, temperature, wind, solar altitude, cloud cover, and humidity. Equations for performance of flat plate solar collectors and sensible heat storage systems were developed and programmed with the above weather variables and with eight design parameters comprising house size, collector size, storage size, collector tilt, number of transparent surfaces in collector, hot water demand, insulation on storage unit, and thermal capacity of collector. Capital and operating costs were quantitatively related to heating system design parameters, and the values of all design variables which yielded lowest annual heating cost in each city were then selected.The findings are presented in the form of two tables and ten graphs, showing heating costs as functions of various design and location factors. The relative importance of each factor is discussed, and the overall costs of solar heating are compared with the costs of conventional heat supply in each location. The method for designing the least-cost combination of solar and conventional heat supplies is also shown, and an example of the use of the method is presented.     

Economic evaluation and optimization of solar heating systems

A procedure is developed for assessing the economic viability of a solar heating system in terms of the life cycle savings of a solar heating system over a conventional heating system. The life cycle savings is expressed in a generalized formby introducing two economic parameters, P₁ and P₂, which relate all life cycle cost considerations to the first year fuel cost or the initial solar system investment cost. Using the generalized life cycle savings equation, a method is developed for calculating the solar heating system design which maximizes the life cycle savings. A similar method is developed for determining the set of economic conditions at which the optimal solar heating system design is just competitive with the conventional heating system. The results of these optimization methods can be presented in tabular or graphical form. The sensitivity of the economic evaluation and optimization calculations to uncertainties in constituent thermal and economic variables is also investigated.     

大庆地区太阳能地板辐射采暖研究与经济分析

设计了太阳能地板辐射采暖系统,给出了系统的工作原理。探讨了集热器单位面积有效利用能和集热器效率的计算方法。通过经济分析,得到大庆市某60 m2平顶民房安装太阳能地板辐射采暖的年计算费用为1 485元;安装散热器采暖年计算费用为1991元。经济分析结果表明,太阳能地板辐射采暖系统具有良好的经济效益。     

太阳能吸收式空调系统的经济性分析

针对一个特定的对象,进行了太阳能吸收式空调系统寿命周期内的模拟计算及影响因素的分析,结果表明：（1）单纯太阳能空调（无采暖与热水供应）的经济性很差,太阳能空调与供热的复合系统的经济性要优于单纯的太阳能空调系统;（2）太阳能采暖与空调的复合系统,采暖与供冷的负荷比对系统的经济性有很大影响,即使在最佳的负荷比时仍无法和常规的系统竞争;（3）太阳能与生活热水系统的负荷系统中,热水负荷所占比重越大,经济性越好,当太阳能空调使用生活热水系统夏季多余的热量时,太阳能空调系统经济上可以和天然气锅炉＋电动制冷机竞争,并具有很好的节能性和环境效益。     

Assessment of government support for the household adoption of micro-generation systems in Korea

This paper investigates how Korean government support affects household adoption of renewable energy-based micro-generation systems by analyzing household preferences in relation to the costs and benefits of system installation and different kinds of government support. The research adopts a discrete choice experiment approach and focuses on two micro-generation technologies: solar voltaic and solar thermal. Our empirical analysis revealed firstly that households prefer micro-generation systems that have low installation costs but high energy saving benefits and long warranty periods; and secondly that households prefer direct subsidies to low-interest loans. However, we also found that households are reluctant to install photovoltaic or solar thermal systems in reality because they see the cost of system installation as being higher than the benefits they would receive from such installation. In short, while existing government supports are somewhat effective in promoting household adoption of micro-generation systems, there also exists the obstacle that the majority of households are unwilling to install such systems despite government support. Thus several policy improvements, which focus on increasing the benefits and decreasing the installation costs of micro-generation systems, are suggested in this paper.     

A simplified method for direct calculation of the annual load fraction of solar systems for space heating

Availability of data about long-term system performance is a first step towards economic analysis and optimization of solar systems. The use of detailed computer simulation techniques or even design methods such as the f-chart for evaluating system performance may be cumbersome for engineers and architects. In this paper, we present a simplified method to predict the annual system performance. The method allows direct calculation of the annual solar load fraction, for a specific location, as a function of collector area and design parameters. This method is based on a correlation of data generated by using the f-chart method. Because of its simplicity and excellent agreement with f-chart calculations, the present method should be a useful design aid for sizing and selecting solar systems for space heating.     

Solar absorption cooling feasibility

The feasibility of small scale solar absorption cooling systems is dependent upon its technical and economically competitive position with respect to other cooling systems alternatives. Technical feasibility can be shown by comparisons of the thermodynamic efficiency of solar absorption cooling with conventional vapor-compression cooling equipment and by reference to numerous experimental evaluations. Economic feasibility is heavily dependent upon the financial parameters assumed (in particular the inflation rate of conventional fuel costs). In particular cases, i.e. particular assumptions of the financial parameters, economic feasibility of solar absorption cooling can be demonstrated.     

An analysis of solar heating systems that use vapor-compression cycles

This paper analyzes the technical and economic performance of solar heating systems that use vapor-compression cycles, circulating a compressible fluid as the working fluid. With conventional solar heating systems that use water or as their working fluid, the collector inlet temperature is equal to that of the storage outlet temperature. Operating the system on a cold day can result in large thermal losses to the surroundings and, thus, low useful heat gains. A vapor-compression cycle may be attractive because it allows the collector inlet temperature to be lowered so that the heat gain of the collector can be increased. Such a system is simulated and a preliminary economic analysis performed. The results indicate that the vapor-compression system can collect almost 50% more solar energy than a conventional system if the collector area of the two systems are the same.     

Economic evaluation of energy saving measures in a common type of Greek building

This paper deals with the economic analysis and evaluation of various energy saving measures in the building sector, focusing on a domestic detached house in Greece, i.e. in a typical Mediterranean climate. In order to detect the energy saving measures that, in addition to energy benefits, can also provide economic profits, the study examines the following measures: all kinds of insulation; upgrading of the heating system; use of thermal solar systems; upgrading of lighting; upgrading of electric appliances; upgrading of the cooling system. The economic evaluation methods used for ranking the energy saving measures are the Net Present Value, the Internal Rate of Return, the Savings to Investment Ratio and the Depreciated Payback Period. It has been found that amongst the most effective energy saving methods are the upgrading of lighting, the insulation of the roof of the building and the installation of an automatic temperature control system.     

Techno-economic performance analysis of solar cooling systems

Vapour absorption cooling systems, powered by solar thermal energy, are now commercially manufactured in sizes ranging from 1.5 to over 20 RT (one refrigeration ton = 3.51 kW of cooling). The needed thermal energy at appropriate temperature potential can either be provided by solar thermal collectors or else from a solar pond. The paper gives the assessment criteria and results for technical and economic evaluation of the performance of absorption chiller using a solar pond. These results, based on Kuwait's environmental data and costs, have been compared with three alternate cooling systems, namely:

• 1 Solar thermal collector absorption cooling system.
• 2 Solar photovoltaic cooling system.
• 3 Standard vapour compression cooling system.

The criteria, used for performance evaluation of the solar cooling systems on a technical basis, consists of assessing the extent to which such systems can make a positive contribution in a conserving fossil fuel. This is done by first estimating the total electrical energy needed by the standard system (defined in para. 3 above) to produce one unit of cooling output. Solar cooling systems are then analysed and compared with a standard system to establish their electrical energy saving or generation capability, after accounting for the parasitic electrical energy used in pump/fan motors and equivalent energy needed for the production of soft water (used-up in the cooling tower) from seawater desalination. The economic analysis considers the cost and life of subsystems and that of the electrical and water desalination plants to arrive at the unit cooling cost. The unit cooling is defined as the ratio of amortized capital investments plus operation and maintenance costs over the year and the total yearly cooling production by the system. The results show that the solar pond absorption cooling system is the closest competitor to the conventional cooling system.     

Passive and active residential solar heating: A comparative economic analysis of select designs

This paper compares four passive solar heating concepts to a conventional air collector/rock storage system. Masonry (Trombe) and water walls are considered in the presence and absence of night insulation. The performance of optimally sized systems is evaluated on a state-by-state basis. The effects of low interest loans and National Energy Act (NBA) income tax credits are examined. With natural gas as the alternative fuel, the passive designs evaluated here offer more promise than the active system. This is true with or without inclusion of incentives, although either incentive option enhances economic performance. The passive designs evaluated in this paper are economically competitive against the electric resistance alternative in all but a few states. Moreover, on a life cycle cost basis, these designs are feasible today. Although the optimal solar fractions are generally low, passive designs offer the opportunity to incorporate solar heating into a new home at costs much less than their active counterparts. This is because there are no discernible fixed costs, thereby allowing a simple movement from zero to 100% solar when evaluating economic feasibility. When both active and passive design are shown to be cost competitive against alternative fuels, higher solar fractions will be associated with the active systems. This is principally due to the substantial fixed cost component of active systems, which forces one to achieve a given solar fraction before economic feasibility can be shown.     

Simulation and cost optimization of solar heating of buildings in adverse solar regions

In the present study a model has been developed which simulates the effects of hourly weather conditions on the performance and cost of a combined solar/conventional heating system for buildings in cold, cloudy climates. The model exhibits the effects of several system and cost parameters on combined system cost so that optimal designs can be determined.Performance and cost results are presented for 1971 Ottawa, Ontario, weather data. The economic analysis, which treats both collector and conventional system fuel costs parametrically, shows that solar heating of a typical house in cold, cloudy climates is economically competitive with fuel oil heating only if the price of oil rises to approximately 80¢/gal.     

大庆地区三种类型被动式太阳房的对比分析

本文为大庆地区设计了三种常见类型的被动式太阳房.通过太阳房采暖设计的SLR法进行热工设计计算得到直接受益式、集热蓄热墙式和附加阳光间式的节能率分别为0.66、0.59和0.71,节能效果均比较好.采用太阳房在寿命期内的资金节省SAV为经济评价指标,分析计算结果表明,直接受益式被动太阳房在寿命期内的资金节省SAV为35077.06元,回收年限仅为3.19年,阐明了直接受益式被动太阳房的优选性.     

Cost-effectiveness of energy efficiency programmes—evaluating the impacts of a regional programme in France

This paper presents the evaluation of a regional energy efficiency programme implemented in two “départements” of France. électricité de France (EDF), a French energy company, provides refurbishment advice and financial incentives to end-users in the residential sector as well as specific training courses and certification to local installation contractors and building firms. Refurbishment measures analysed in this paper are efficient space heating equipment (condensing boilers, heat pumps and wood stoves or boilers), solar water heating systems and the installation of double-glazed windows. A billing analysis based on a survey of programme participants’ energy consumption is used to calculate the energy savings attributed to the programme. In order to receive an economic feedback of this demonstration programme, the evaluation of both saved energy and programme costs is of importance. Detailed knowledge of the programme’s cost-effectiveness is essential for EDF to achieve the saving obligations imposed by the French White Certificate scheme at the lowest cost. Results of this evaluation can support the development and implementation of further energy efficiency programmes with similar characteristics in other regions of France. The cost-effectiveness is determined from the perspective of the programme participant and the society as well as the energy company in charge of the programme. All cost and benefit components are calculated in Euro per kilowatt-hour, which allows a direct comparison of levelized costs of conserved energy with the avoidable costs of the energy supply system.     

Application of the genetic algorithm for optimisation of large solar hot water systems

An implementation of the genetic algorithm in a design support tool for (large) solar hot water systems is described. The tool calculates the yield and the costs of solar hot water systems based on technical and financial data of the system components. The genetic algorithm allows for optimisation of separate variables such as the collector type, the number of collectors, the heat storage mass and the collector heat exchanger area. Optimisation can be focussed on, for example, payback time and CO₂ emission reduction. Constraints such as maximum initial costs and installation space are taken into account. The applicability of the genetic algorithm was tested for optimisation of large solar hot water systems. Among others, the sensitivity of the optimum system design to the tap water draw-off and the draw-off pattern has been determined using the optimisation algorithm. As the genetic algorithm is a discrete optimisation tool and is implemented in the design tool through the use of databases, the number of variables in principle is free of choice.     

太阳能、热泵辅助燃气供热系统实验研究

搭建了太阳能、热泵辅助燃气的供热系统测试平台,对太阳能辅助燃气供热系统、热泵辅助燃气供热系统以及太阳能、热泵辅助燃气供热系统的热性能进行测试,并对三种供热系统的经济环境效益进行分析。试验结果表明,试验条件下,三种供热系统的修正后一次能源利用率分别为93.3%、92.8%、103.9%,与燃气供热系统相比,节能率分别为3.8%、3.2%和15.6%,年运行费用可节约275、236、1 016￥,每年减排CO₂为123.00、106.00、455.00 kg。