PV and CHP hybrid systems

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Small scale CHP systems offer the opportunity to further enhance the penetration level of solar electricity on the grid. These coupled projects look at the viability of this approach to create a massive distributed generation based electrical system, where individual homes provide their own power and heat.

Contents

[edit] Expanding Photovoltaic Penetration with Residential Distributed Generation from Hybrid Solar Photovoltaic + Combined Heat and Power Systems

[edit] Abstract

The recent development of small scale combined heat and power (CHP) systems has provided the opportunity for in house power backup of residential scale photovoltaic (PV) arrays. This paper investigates the potential of deploying a distributed network of PV+CHP hybrid systems in order increase the PV penetration level in the U.S. The temporal distribution of solar flux, electrical and heating requirements for representative U.S. single family residences were analyzed and the results clearly show that hybridizing CHP with PV can enable additional PV deployment above what is possible with a conventional centralized electric generation system. The technical evolution of such PV+CHP hybrid systems was developed from the present (near market) technology through four generations, which enable high utilization rates of both PV generated electricity and CHP generated heat. A method to determine the maximum percent of PV generated electricity on the grid without energy storage was derived and applied to an example area. The results show that a PV+CHP hybrid system not only has the potential to radically reduce energy waste in the status quo electrical and heating systems, but it also enables the share of solar PV to be expanded by about a factor of five.

[edit] Dispatch Strategy and Model for Hybrid Photovoltaic and Combined Heating, Cooling, and Power Systems

[edit] Abstract

The advent of small scale combined heat and power (CHP) systems has provided the opportunity for in-house power backup of residential-scale photovoltaic (PV) arrays. These hybrid systems enjoy a symbiotic relationship between components, but have large thermal energy wastes when operated to provide 100% of the electric load. In a novel hybrid system is proposed here of PV-trigeneration. In order to reduce waste from excess heat, an absorption chiller has been proposed to utilize the CHP-produced thermal energy for cooling of PV-CHP system. This complexity has brought forth entirely new levels of system dynamics and interaction that require numerical simulation in order to optimize system design. This paper introduces a dispatch strategy for such a system that accounts for electric, domestic hot water, space heating, and space cooling load categories. The dispatch strategy was simulated for a typical home in Vancouver and the results indicate an improvement in performance of over 50% available when a PV-CHP system also accounts for cooling. The dispatch strategy and simulation are to be used as a foundation for an optimization algorithm of such systems.

[edit] Optimizing Design of Household Scale Hybrid Solar Photovoltaic + Combined Heat and Power Systems for Ontario

  • P. Derewonko and J.M. Pearce, “Optimizing Design of Household Scale Hybrid Solar Photovoltaic + Combined Heat and Power Systems for Ontario”, Photovoltaic Specialists Conference (PVSC), 2009 34th IEEE, pp.1274-1279, 7-12 June 2009. Available [1]

[edit] Abstract

This paper investigates the feasibility of implementing a hybrid solar photovoltaic (PV) + combined heat and power (CHP) and battery bank system for a residential application to generate reliable base load power to the grid in Ontario. Deploying PV on a large­scale has a penetration level threshold due to the inherent power supply intermittency associated with the solar resource. By creating a hybrid PV+CHP system there is potential of increasing the PV penetration level. One year of one second resolution pyranometer data is analyzed for Kingston Ontario to determine the total amount of PV energy generation potential, the rate of change of PV power generation due to intermittent cloud cover, and the daily CHP run time required to supply reliable base load power to the grid using this hybrid system.This analysis found that the vast majority of solar energy fluctuations are small in magnitude and the worst case energy fluctuation can be accommodated by relatively inexpensive and simple storage with conventional lead ­acid batteries. For systems where the PV power rating is identical to the CHP unit, the CHP unit must run for more than twenty hours a day for the system to meet the base load requirement during the winter months. This provides a fortunate supply of heat, which can be used for the needed home heating. This paper provides analysis for a preliminary base line system.

[edit] Institutional-Scale Operational Symbiosis of Photovoltaic and Cogeneration Energy Systems

  • M. Mostofi, A. H. Nosrat, and J. M. Pearce, “Institutional-Scale Operational Symbiosis of Photovoltaic and Cogeneration Energy Systems” International Journal of Environmental Science and Technology 8(1), pp. 31-44, 2011. Available open access: [2]

[edit] Abstract

Due to the negative environmental effects of fossil fuel combustion there is a growing interest in both improved efficiency in energy management and a large-scale transition to renewable energy systems. Using both of these strategies, a large institutional-scale hybrid energy system is proposed here, which incorporates both solar photovoltaic (PV) energy conversion to supply renewable energy and cogeneration (cogen) to improve efficiency. In this case the PV reduces the run time for the cogen to meet load, particularly in peaking air conditioning times. In turn, however, the cogen system is used to provide power back up for the PV during the night and adverse weather conditions. To illustrate the operational symbiosis between these two technical systems, this paper provides a case study of a hybrid PV and cogeneration system for the Taleghani hospital in Tehran. Three design scenarios using only existing technologies for such a hybrid system are considered here: i) single cogen+PV, ii) double cogen+PV, iii) single cogen+PV+storage. Numerical simulations for PV and cogen performance both before and after incorporating improved thermal energy management and high efficiency lighting were considered. The results show that the total amount of natural gas required to provide for the hospitals needs could be lowered from the status quo by 55% for scenario 1 and 62% for both scenario 2 and 3, respectively. This significant improvement in natural gas consumption illustrates the potential of hybridizing solar photovoltaic systems and cogeneration systems on a large scale.

[edit] Improved Performance of Hybrid Photovoltaic-Trigeneration Systems Over Photovoltaic-Cogen Systems Including Effects of Battery Storage

  • A.H. Nosrat, L.G. Swan, J.M. Pearce, "Improved Performance of Hybrid Photovoltaic-Trigeneration Systems Over Photovoltaic-Cogen Systems Including Effects of Battery Storage", Energy 49, pp. 366-374 (2013). DOI, open access.

[edit] Abstract

Recent work has proposed that hybridization of residential-scale cogeneration with roof-mounted solar PV (photovoltaic) arrays can increase the PV penetration level in ideal situations by a factor of five. In regions where there is a significant cooling load PV-cogen hybrid systems could be coupled to an absorption chiller to utilize waste heat from the cogen unit. In order to investigate realistic (non-ideal) loads that such a hybrid system would need to service, a new numerical simulation called PVTOM (PV-trigeneration optimization model) was created and coupled to the results of the established CHREM (Canadian Hybrid Residential End-Use Energy and Emissions Model). In this paper, PVTOM is applied to representative houses in select Canadian regions, which experience cooling loads, to assess the fuel utilization efficiency and reduction in greenhouse gas emissions from hybrid PV-cogen and trigen systems in comparison with conventional systems. Results of the optimization runs are provided and the efficacy of PV-cogen and PV-trigen systems is discussed. Both PV-trigen and PV-cogen systems have demonstrated to be more effective at reducing emissions when compared to the current combination of centralized power plants and household heating technologies in some regions.

[edit] See also