Thermodynamic and Cost Analyses of a Residential Hybrid PV–Fuel Cell–Battery System for a Canadian House

Abstract

A residential photovoltaic (PV)-based hydrogen fuel cell system is analyzed using energy and exergy methods, and its monthly performance is investigated. The PV system is accompanied by a water electrolyser for hydrogen production, a lead acid battery pack, and a solid oxide fuel cell (SOFC) for reconverting the hydrogen produced to electricity during periods of solar unavailability. The solar irradiance is based on a monthly average in Toronto in 2011. The energy and exergy analysis results reported include the PV power output and the shares attributable to the battery and the SOFC in meeting the electrical demand. The exergy destructions of the main components and the overall efficiencies are presented. A cost analysis is performed to determine the electricity unit cost over the system lifetime.

Nomenclature

ex :

Specific exergy, kJ/kg

$\overset{.}{ En}$ :

Energy flow rate, kW

$\overset{.}{ Ex}$ :

Exergy flow rate, kW

G :

Solar irradiance, W/m²

I _L :

PV light current, A

I ₀ :

Reverse saturation current, A

I :

PV electric current, A

k :

Boltzmann constant

k _t :

Manufacturer supplied temperature coefficient of short-circuit current, A/°C

LHV:

Lower heating value, kJ/kg

$\dot{m}$ :

Mass flow rate, kg/s

P :

Power, kW

$\dot{Q}$ :

Heat transfer rate, kW

R _s :

Series resistance of the PV cells, Ohm

T :

Temperature, K

V :

Voltage, V

$\dot{W}$ :

Work rate, kW

γ:

PV cell shape factor

η:

Energy efficiency, %

ψ:

Exergy efficiency, %

0:

Ambient condition

cell:

PV cells

H₂ :

Hydrogen

in, el:

Input to the electrolyser

mp:

Maximum power

SOFC:

Solid oxide fuel cell

CHP:

Combined heat and power

PV:

Photovoltaic

SOFC:

Solid oxide fuel cell

STC:

Standard test condition