The term ‘system modelling’ refers to the way in which a system is sized for a particular location and application. System modelling takes into account all three variables of the energy budget and how those factors affect the performance of system components.
When modelling a system, solar LED lighting companies typically look at weather data from agencies such as NASA to determine what the solar conditions are in a given location. By understanding how much energy the system will be able to collect, the system can be sized based on the application (energy spend) and operating profile (energy savings) the user has specified.
Solar energy is not uniform across the planet’s surface. Even within relatively small regions, solar energy may vary greatly. For example, in areas around the Great Lakes the available solar energy can be quite different from areas on one side of the region to the other. It is important that systems be modelled to a location as close to the installation site as possible to ensure accurate sizing and appropriate autonomy.
Battery performance over time must also be taken into account in during system modelling. Battery performance is affected by various factors including temperatureBatteries, control of charging and discharging, and battery characteristics. The modelling system should take all parameters into account to accurately gauge battery performance and lifetime.
Individual component degradation over the lifetime of the system is another important factor in system modelling. A solar panel or battery will not perform the same way after of five years of operation as it did on the first day it was installed. This difference must be taken into account to ensure the reliable long-term performance of the system in its environment.
Autonomy is a rainy-day fund used to deal with times when solar income is lower than average. Autonomy is typically defined as the length of time a solar LED lighting system will run from full charge to light failure without being charged by the solar panels. Locations that have long periods of cloud cover require more autonomy than those with consistently sunny weather. Organizations like NASA report the “equivalent number of no-sun days” as a way of quantifying how much solar deficit can be expected in a location.
A system should be modelled to operate on the average amount of solar income expected for its installation location and batteries should be sized such that the system is able to operate reliably for the number of no-sun days in that location. This will ensure maximum system performance regardless of season or prevailing weather conditions.
In addition to expected conditions, systems should be designed to handle extreme operating conditions such as solar panel shading or unusually long spells of bad weather. When a typical solar LED lighting system encounters conditions that take it beyond the expected number of no-sun days, the light will continue to run at full output for as long as the batteries will support the power draw. By the time the light fails, the batteries have been deeply discharged because, although the system has been run at full output all night, the batteries have not been fully charged during the day. This repeated under-charging severely damages the batteries and affects the long-term health of the system. The end result is ongoing, costly battery replacements.
Carmanah solar LED lighting systems incorporate enhanced autonomy, which preserves battery health and allows systems to provide useful light even when extreme operating conditions exist.
A function of the energy management system (EMS), enhanced autonomy enables the EverGEN lighting system to slow its consumption of energy when no-sun conditions extend beyond what is expected. Light levels will step down incrementally as the EMS continues to register poor charging conditions. By stepping light levels down incrementally, EverGEN systems provide useful light much longer than systems functioning with typical autonomy. By keeping the energy spent on light output within the safe limits of the battery’s energy storage capacity, batteries do not deep-discharge, effectively preserving the long-term health of the system. Once the extreme conditions pass, normal system function returns quickly and without impact on battery health and function.
The contents of this page are copyrighted with Carmanah Technologies Corp. The original content can be found at http://carmanah.com/lighting/technology/system-modelling
"Over the last 12 months, council has been extremely happy with how the solar bollards have stood up..
- David Woodroofe
Community Development Officer, Wakefield Regional Council
Our solar bollards have been installed and look wonderful! Everyone is very pleased with their appea..
- Rae D'Espirit
Residents Association, Aldinga Eco Village, SA
With the Barron River in full flood, completely submerging the First Light Bollards on the walkway. ..
- Duncan Muirson
Department of Transport and Main Roads