As a group we have reviewed a domestic PV-fuel cell energy system. The system requires only the direct inputs of water and sunlight into the proprietary process of which the main system components are a PV array, electrolyser, hydrogen storage, and a fuel cell. The basic system is illustrated below.

Figure 1: Basic system diagram

The basic principles of the solar hydrogen system is that the photovoltaic array supplies electricity directly to an autonomous dwelling in periods of high solar irradiance and surplus electricity is used to generate hydrogen gas that can be stored on site. The hydrogen gas is produced by splitting water (H2O), using an electrolyser, into its elemental components, oxygen (which is vented to the atmosphere) and hydrogen (stored as a fuel). In periods of low solar irradiance (for example during night or during the winter), long-term seasonal storage of the hydrogen can be used to power the electrical loads within the dwelling. 

The key influential factors in our decision to study the PV-fuel cell system for Part B of the MSc 'Energy Systems & the Environment' are as follows: 

• The system produces negligible environmental emissions.
  

•  The technological advances and the increasing economic viability in the manufacture of photovoltaics.
  

•  The approaching market readiness of fuel cells, potentially enabling hydrogen to become a dominant energy provider.
  

•  The large potential market for the system. Over 1 million houses are currently isolated from the grid in the EU.

The outcome of the project is a comparison of the implementation of the PV-fuel cell system in three different localities, with vastly differing climates; Glasgow in Scotland, Catania in Italy and Phoenix in the U.S. This has been achieved using results that have been attained for each locality using demand/supply matching software.

 The results for each location have been classified as follows:

• The number of PV panels required to supply the electrical load of an autonomous dwelling.

•  The hydrogen storage capacity (m3) required for a period of a year.

•  The rating of fuel cell required (kW).

•  The rating of the system inverter required (kW).

The project outcomes are a comparative review of these variables in terms of the technical, environmental and economic feasibility of the PV-fuel cell system in each of the three locations.

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