PV Hybrid Systems

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=82 BGCOLOR="#006699" TEXT="#080000"> <div> <FONT SIZE="5" COLOR="#FFFFFF" FACE="Arial" ><B>IEA PVPS Task 11 - PV Hybrids and Mini Grids</B></FONT><B>     |     </B><A HREF="index.htm" TARGET="_top" TITLE="IEA PVPS Task 11 PV Hybrids and Mini Gr"><U><B>H</B></U></A><A HREF="index.htm" TARGET="_top" TITLE="IEA PVPS Task 11 PV Hybrids and Mini Gr"><U><B>ome</B></U></A></div> <div> <B>PV Hybrid Systems</B>   |   <A HREF="id34.htm" TARGET="_top" TITLE="Minigrids"><U>Mini-grids</U></A>   |   <A HREF="id35.htm" TARGET="_top" TITLE="Village microgrids"><U>Village microgrids</U></A>   |   <A HREF="id36.htm" TARGET="_top" TITLE="Diesel mini grids"><U>Diesel mini grids</U></A>   |   <A HREF="id37.htm" TARGET="_top" TITLE="Urban minigrids"><U>Urban mini-grids</U></A></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#FFCC66" TEXT="#080000"> <div> <A HREF="id18.htm" TARGET="_top" TITLE="Mission"><U>Mission</U></A></div> <div> <A HREF="id27.htm" TARGET="_top" TITLE="Work Plan"><U>Work Plan</U></A></div> <div> <A HREF="id17.htm" TARGET="_top" TITLE="Event Calendar"><U>Event Calendar</U></A></div> <div> <A HREF="id19.htm" TARGET="_top" TITLE="Contact Us"><U>Contact Us</U></A></div> <div> <A HREF="id20.htm" TARGET="_top" TITLE="Participant List"><U>Participant List</U></A></div> <div> <A HREF="id25.htm" TARGET="_top" TITLE="Related Links"><U>Related Links</U></A></div> <div> <A HREF="id26.htm" TARGET="_top" TITLE="Public Downloads"><U>Public Downloads</U></A></div> <div> <A HREF="id31.htm" TARGET="_top" TITLE="Participant Area"><U>Participant Area</U></A></div> </td> <td valign="top" height=398 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <I>PV Hybrid Systems</I></div> <div> Hybrid energy systems combine multiple energy generation or storage technologies to create an electricity generation system that optimizes the characteristics of the individual generation sources.  For example, PV hybrid  systems usually combine photovoltaic (PV) generation of electricity with energy storage (typically a rechargeable battery) and a fossil fuel engine generator (genset).  </div> <bR> <div> PV generators have no fuel costs, produce no greenhouse gases or other air contaminants, are quiet and require minimal maintenance, but they have relatively high capital cost and produce power intermittently, depending on the amount of sunlight available (they are <I>non-dispatchable).  </I>Fossil fuel gensets, on the other hand, have low capital cost and can generate power on demand (they are <I>dispatchable</I>) but have high fuel and maintenance costs, produce greenhouse gases and other air pollution, and are noisy.   A PV hybrid system uses PV power (and energy storage), when sunlight is available, to generate and store energy and uses the fossil fuel generator as an energy source when sunlight is limited or unavailable for extended periods.  By optimizing the size of the PV array, the battery, and the genset, and through proper control strategy, an economic compromise between the capital cost of the PV array and the battery and the operating cost and emissions of the genset can be achieved.</div> <bR> <div> The environmental arguments for PV hybrids are similar to those for hybrid automobiles.  While it may be desirable to eliminate the fossil fuel engine in an automobile completely, current battery or fuel cell technology does not have the performance and cost to allow this.  Hybrid automobiles represent an intermediate step that provides emission reductions and provides manufacturers with real market experience with the technologies required to eventually make pure electric vehicles practical.   Similarly, PV hybrids using fossil fuel engine gensets are a practical intermediate step towards even cleaner systems that will appear when PV costs go down, advanced battery technology arrives, and cleaner fossil fuel generators are available.</div> <bR> <div> While PV (and other) hybrid systems are practical today, there are a number of obstacles, both technical and non-technical, to their wider use.  These include</div> <bR> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Inadequate energy storage technology.  Most current PV hybrid systems rely on lead-acid batteries which have limited lifetime and relatively low "round-trip" efficiency - thus the cost of energy cycled through the battery is much higher than the cost of energy delivered directly to the load.</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Complex design process.  Software tools are available to assist in the design of PV hybrid systems, but design still requires careful analysis of the available energy and the load profile, and trade-offs among many design options.  Design cost  is usually considerably higher than for a grid-tie PV system or a simple genset installation. </div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Limited component interoperability.  Control and data networking systems for PV hybrid systems are not standardized and integration of components from different manufacturers into a working system can be a complex and expensive task.</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Financial disincentives.   It may be difficult to obtain the significant up-front investment required to install a PV hybrid system,  or the required financial hurdle (interest rate, applied discount rate, or payback period) is unreasonalby high.  Or fossil fuel  may be subsidized, skewing the financial incentives towards a genset only solution.</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.gif" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Operation and maintenance infastructure.  The infrastructure (trained personnel, service facilities, spare parts) may not be available to to ensure long-term, reliable operation of the system.   </div> </td> </tr></table></body>