Solar Lighting ROI
Solar Street Light Savings
I¡¯m often asked about solar lighting ROI based on electricity savings. It is true that you will never get any electric bills from the sun. But you don¡¯t need to wait for future returns to justify your solar lighting installation today.
Solar lighting saves you money right from the start. You will avoid trenching, wiring, remediation, and hook-up costs. And it allows you to install lighting in places you couldn¡¯t consider in the past because of cost or access.
How much will you save?
Costs for an outdoor lighting project vary based on local labor costs, site conditions and the availability of connections. Here¡¯s a framework to help you understand solar lighting savings.
Total cost of ownership considers all costs for the life of the project. Often, the total cost of ownership will be lower for solar than for grid-tied lighting.
If electricity costs continue to increase and battery costs decline as expected, the savings are even greater.
How much will the equipment cost?
The cost of your commercial solar lighting equipment depends on your geographic location and application. Expect the solar lighting to cost more than traditional grid-tied commercial lighting equipment. After all, it includes not only an LED luminaire but also the equipment to generate its own power.
You should steer clear of off-the-shelf products. They don¡¯t include an energy balance for your location and application. Off-the-shelf products advertise the greatest light output potential of the fixture. The advertised wattage often doesn¡¯t reflect performance for your location or winter conditions.
TIP: Be sure you are comparing apples-to-apples performance. An off-the-shelf solar lighting product that costs less than a commercial LED fixture is not going to provide equal performance or durability. You might get better results from a few high-quality systems versus a lot of low-cost products. To compare lighting performance get a proposal that includes a lighting design. Make sure the design uses winter (worst case) light output.
How much will installation cost?
Installation costs for your grid-tied lighting can be at least as much as the equipment. This is where you are likely to see the biggest solar lighting savings.
Trenching and wiring under normal conditions costs $25 ¨C $50 per foot. Rock, tree roots, contamination, or water considerations drive trenching costs even higher. You will also need to pay for high voltage electrical equipment. This includes step-down transformers, panels, and switchgear. Bringing electricity to a site where it¡¯s not already available can be the greatest cost.
Request an estimate from a local electrical contractor to get grid-tied installation costs. Decide what type of pole you¡¯d like to use and have the lighting layout prepared before requesting an estimate. Direct burial aluminum poles save time and money for both grid and solar lighting.
What about maintenance?
A commercial quality LED light fixture will likely be maintenance free for 10 ¨C 20 years. That doesn¡¯t mean LED has eliminated maintenance costs for grid-tied lighting. The grid is vulnerable to lots of nasty issues. Some of them are voltage dips, cut underground cables, damage from rodents, and wire theft. Grid issues are less frequent, but time consuming and costly. Overhead wires need maintenance for tree growth and storm damage.
Solar lighting systems need battery replacements. With a well-designed system, the battery cost will be offset by the savings on electricity.
Not all solar lighting products are equal. Saving money on the cost of the product can often bury you in maintenance costs. That is if you can find the replacement packs. Power 365 uses NiMH technology and conservative sizing. This approach delivers a maintenance-free battery life of 10-12 years. We have 100,000 solar systems installed. You can count on replacements when you need them.
Battery life depends on the type of battery, the formulation, and quality control. Get a complete proposal and energy study to better understand what you can expect.
Are there other costs to consider?
Some costs are hard to convert to a dollar figure but are very real. Is there a liability cost associated with ¡°trying¡± cheap equipment? Is there a public safety cost when the utility turns the power off or fails? Will waiting to light a hard-to-reach area expose you to liability costs? Does your community put a value on reducing carbon emissions?