- Which battery models should I consider for my solar outdoor lighting system?
- What is the expected battery life cycle in solar street light applications?
- What is the price of each solar battery type under consideration?
- What is the battery maintenance cost and how frequently it should be monitored?
Question 1: Which battery models should I consider for my solar street lights?
- Flooded lead acid battery
- Sealed lead acid battery
Flooded lead acid battery was first developed in 1859 by the French physicist Gaston Planté. It is the oldest type of rechargeable battery. The flooded battery contains liquid electrolytes and is quite cheap when compared to newly developed battery technologies. Flooded lead-acid batteries are commonly used when surge current is not of high importance, as they are designed to provide higher energy densities. They are usually used for energy storage and UPS systems in cell phone towers, hospitals and other stand-alone power systems.
To conclude, the winner in this category is the AGM battery model, but only if connected to a smart solar charge controller which can optimize its performance and prolong its life cycle. If you want to find out more about this topic, check out this blog: How to increase solar street light performance and reliability?
Question 3: What is the price of each solar battery type under consideration?
- Price: We know that low price always sounds good. However, when you buy cheap solar battery you will have to replace it after 2 to 3 years, which will drastically increase the cost of your initial investment. That is why you should always try to find the right balance between pricing, performance and solar technology that is available in the market.
- Capacity: If you want your solar battery to last longer, you need to make proper configuration of your solar off-grid lighting system. The following article will give you insights on how to configure your solar LED street lights: WHAT'S IN YOUR SMART SOLAR STREET LIGHT: SYSTEM DESIGN AND COMPONENTS
- Voltage: Battery voltage needs to be aligned with the rest of the solar outdoor lighting system. For example, if your loads (LED lights) are 24 Volts, you will need to go either with two serially connected batteries (2x12 Volts) or with one solar battery (1x24 Volts).
All of the aforementioned tips have to be considered when purchasing a certain type of solar battery since these costs will add up to your initial investment calculations. For a smart solar outdoor lighting system to function over a 25 year period, my estimation of the total cost of an AGM battery model is up to 1000 USD (including replenishment costs).
Question 4: What is the solar battery maintenance cost and how frequently it should be monitored?
Both AGM and Lithium-ion batteries do not need to be refilled and significantly maintained in the long run, which puts them at advantage when compared to the flooded battery model. When you have solar street lights projects with solar batteries buried underground during installation (if the solar companies tell you differently, please ask them how do they protect the batteries against extreme temperatures), then you are not going to be able to maintain them much. As we have explained previously, the solution in this case is to have a smart off-grid controller as part of your solar LED street light system. This smart device will provide you with the ability to remotely control your solar battery performance and even predict how long the battery will last.
Final Advice: If you are not able to monitor and adapt battery charging according to your current energy consumption and external temperatures, your solar battery life span will be around 3 years. This means that if you go with AGM batteries without remote control features, you will end up paying every 3 years for a new battery set.
To conclude, flooded batteries may be a suitable solution for certain solar system applications. However, we have seen that they are not the right choice to make when implementing solar outdoor lighting projects. Lithium-ion batteries may have the longest battery life (the most life cycles), but the pricing tag that comes with them is still not competitive enough to generate a positive ROI from your solar street light project.
AGM (VRLA) seems to be the best choice at the moment, with one caveat in mind: they need to be accompanied by smart technology which will enable the user to remotely control and monitor the battery to ensure longer life and high performance.
Looking forward to your comments, let's discuss and make some progress!