Choosing solar lighting presents an opportunity for dramatic installation cost reductions. It does however present additional challenges for lighting engineers and procurement professionals in deciding what units to purchase.
Below is our Solar Lighting Buying Checklist. It lists all of the information you should look for from any solar lighting manufacturer or distributor. Gathering all of the information below will help you to make an informed decision about the best possible product for your application and give you confidence that you have chosen a high quality product.
A solar panels output is measured in Watts. The higher the wattage, the more energy a panel can produce under the same conditions. As a general rule of thumb, here more is better. The higher wattage your solar panel is, the more energy it will be able to harvest and store during the day allowing for more light at night.
Panel size shows the area of the panel and is measured in M2. This information can be combined with the panel efficiency and solar radiation data to calculate how much power will be generated in a specific location.
Measured in %, solar panel efficiency is a measure of how much sunlight a panel can convert into useable electricity. Panel efficiency is a good indicator of a units quality. The higher the efficiency, the better engineered a product is.
Solar irradiance is the amount of power received from the sun for a given location. Often expressed in kW Hours per Metre2 per day. Whilst solar irradiance is a natural feature rather then a product feature, a knowledgeable and responsible manufacturer or distributor of solar products should be able to provide you this data to help you make an informed choice as to whether solar will work as desired for your project.
We are happy to draw data for any location and recommend NASA’s excellent power data access viewer for anyone wishing to learn more.
A batteries capacity is the amount of electric charge it can deliver at the rated voltage and is measured in amp-hours (Ah) or watt-hours (Wh). The higher volume a units battery is, the greater the number of days backup it will be able to provide in case of overcast weather.
The potential difference or electrical “pressure” contained within a battery. Battery voltage is determined by the batteries internal construction and chemistry and is useful for converting Ah into Wh or vice versa. The formula’s to do this are;
Wh = V*Ah
Ah = Wh/V
There are three types of battery commonly used in solar lighting, each with their own advantages and drawbacks.
Lithium-Ion – Lithium-Ion is the most commonly used battery type for solar lighting and is similar to the batteries you will find in your smartphone or laptop. A low maintenance, high density battery type, Li-Ion batteries have no memory or scheduled cycling.
Lithium-Phosphate (LiFePo4) – An advanced battery type found in high end solar units, Lithium-Phosphate batteries experience a slower rate of capacity loss compared with standard Li-Ion batteries.
Deep Cycle Gel AGM Batteries – Gel AGM batteries allow for a lower price point then LI-Ion or LiFePo4 batteries however their life cycle is not as long.
All batteries degrade over time. A units battery warranty will suggest how long the battery on your unit will last for before needing replacement.
Charge controllers are an important feature of solar lights. They help ensure that a units are working at optimum performance, helping power to last all night.
Programmable on off times and dimming options help to conserve power, as do PIR sensors.
High quality units such as the GFS Aspire, Defender and Stealth feature IoT functionality and remote control. Green Frog’s SAM (Solar Activity Monitor) system allows you to remotely measure the performance of your solar units.
Adjustments to light levels and dimming schedules can then be made to maximise performance of your units.
Units 4 & 5