Solar fundamentals and decision-making tips
Jane Bond, project development manager at SunPower, a global solar technology and energy services provider, shares top considerations for facility managers looking to make a solar investment.
Many commercial facilities, like warehouses, distribution centres, wineries and cold storage buildings, have a large base load requirement for electricity. Typically, this electricity is drawn from the grid and building owners can be subject to volatile network power prices as well as network instability. When energy prices spike or the grid supply cannot meet the facility’s needs, this can significantly impact business operations.
Installing an on-site solar power system can help facility managers save money on energy today and hedge against rising utility rates tomorrow. And, as more business owners transition to solar energy, these benefits are becoming increasingly hard to ignore. By self- generating the power needed, facility owners can reduce grid dependence and lock in energy rates from day one.
However, before moving forward with solar, it is important to determine the total energy generated and savings available over the life of a photovoltaic (PV) installation. Because not all solar is created equal, costs and benefits will differ by technology.
Key variables impacting on solar energy generation
Different solar technologies yield different energy outputs. The energy yielded from any given panel is subject to a number of variables beyond site characteristics. These can include:
Efficiency – The higher a solar panel’s efficiency, the more power generation capacity it has for any given area. This means that a solar power system designed with higher efficiency solar panels would deliver more electricity in less space, than a solar power system designed with lower efficiency solar panels. Higher efficiency panels can make the most out of a space-constrained rooftop.
Performance – How the solar panel performs in real-world conditions will impact the amount of energy it generates. For instance, solar cell performance can be adversely affected by high temperatures. However, the impact of high temperatures will be less consequential in a panel with a lower Normal Operating Cell Temperature (NOCT). Another measurement of how a solar panel will perform is the warranted degradation rate. This is expressed in percentage terms based on the panel’s rated watts at the time of installation. A lower panel degradation rate signals more energy will be generated over the life of the system.
Durability – The solar panel itself must be able to withstand a battering of environmental conditions including extreme heat, cold and wind storms. A common indicator of panel durability is the length of the manufacturer’s warranty, as it is a key indication of confidence in their product.
Main solar PV technologies
There are four main types of solar PV technology commercially available, as shown in Table 1 overleaf.
● can be made flexible, which opens up many new potential applications
● performs well in very high temperatures or in shaded conditions
● mass-production is simple
● the process used to make polycrystalline silicon is less expensive and simpler
● because of lower silicon purity, polycrystalline silicon solar panels are not quite as efficient as monocrystalline silicon solar panels
● made out of high-grade silicon
● thin lines of baked-on metal paste
● soldered copper ribbons on front of cell
● made out of the highest-grade silicon
● highest efficiency rates
● robust against corrosion
● all silicone is exposed to light and unshaded by conduits
Not all solar is created equal
Understanding how solar technologies differ is an important start in assessing the benefit of a solar electricity system. A technology comparison based on a 100-kilowatt
(kW) sized system located in south-east Queensland is shown in Table 2.
Guidelines for a successful solar project
Additional steps facility managers should consider taking before going solar include:
● engaging a Clean Energy Council (CEC) accredited designer, who can be found at www.solaraccreditation.com.au/ consumers/find-an-installer.html
● verifying a CEC-accredited designer’s credentials and requesting energy generation data from any of their prior installations to validate their performance claims about energy yield, as some claims can be unrealistic, and
● determining the ideal solar PV technology and system size that is harmonious with electricity consumption patterns at the site. There is currently little financial incentive to export power to the grid. The primary benefit of a solar power system is gained by self- consumption, whereby retail electricity tariffs can be offset by on-site energy generation.
Ensuring the design takes into account important site variables such as shading and future shading (i.e. from buildings, trees or other structures), orientation toward the sun, tilt (or panel inclination) and surrounding environmental conditions – as these will all have an impact on captured solar irradiation and electricity production.
Evaluating the upfront capital cost of the equipment plus installation, in addition to the ongoing maintenance and component replacement costs that may be required, such as inverters.
Images courtesy of SunPower Corporation.