Overview:

Product Description:

Sizing a photovoltaic (PV) system is easy to do. PV systems can reduce greenhouse gas emissions and provide free electricity. Due to the low current cost of electricity, system costs can generate a range of payback periods depending on where the system is to be installed. If it is in a rural or remote situation, PVs can be less expensive than connecting to the grid. In close-grid connection or urban contexts, payback periods can be from 12 to 20 years.

Nonetheless, many new developments are finding installation of PVs worthwhile either from a marketing or PR ‘feel good’ standpoint or as part of a legislative compliance pathway. One such pathway is through BASIX, which is a way of minimizing overall greenhouse emissions.

The best way of reducing the capital cost of a new PV system is to reduce the energy load on the system. The best way to do this is to:

• avoid consumption where possible  e.g. use climate sensitive design and materials selection to minimise space heating and cooling;
• shift energy sources where possible  e.g. use gas cooking and gas backup solar hot water systems; and
• use the most efficient appliances and lighting possible.

A decision as to whether the system should be stand alone or grid connected then needs to be made. Among the factors to be considered in making this decision are:

• Is the grid reliable?
• Is the extra cost and maintenance of batteries warranted?
• What will the supply authority pay for the power supplied into the grid?
• What is the likely annual income from the Renewable Energy Certificates (RECs)?
• How does the peak energy consumption within the development relate to the peak demand in the grid?

All of these issues can have an impact on the decision to grid connect or stand alone. In urban situations the most ecologically and socially sustainable decision is likely to be grid connected. This ensures that excess energy is available for others to use and as the initial system costs are generally lower and the excess energy is sold to generate additional income, grid connected systems are likely to have the lowest overall cost. A counter view that grid connected systems do nothing to modify overall consumption is worthwhile noting.           

To reduce energy consumption across all dwellings, new regulations have been implemented across Australia that require a minimum standard of performance for most household appliances. Such standards include the Minimum Energy Performance Standards (MEPS) and the Water Efficiency Labelling and Standards (WELS) Scheme.  When buying a new dishwasher or refrigerator, for example, keep in mind that a more energy and (hot) water efficient appliance will facilitate smaller PV array size (and cost).

The following links provide a step-by-step guide to sizing a photovoltaic system. As individual's needs vary significantly, so will PV systems. This guide attempts to cover most scenarios, but modifications may be necessary to optimize system performance.

• System Options
• Electric Demand
• Site Evaluation
• Panel Mounting Angles
• Sizing the Array

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