Solar Energy Microgrid for Remote Locations

We realize that many locations in remote areas may not have electrical power to run the equipment needed to deliver these services, so we have worked with providers to create a solar energy package capable of powering these systems.

Solar Implementation Design

This design of our Solar Kit is different than all off-grid systems we’ve come across.  Since the power requirements needed to provide computer technology to a classroom or clinic is not large (such as with heating or operating large motors), we’ve been able to create a complete system that does not involve AC (Alternating Current).

The following diagram shows the components of a typical solar power system:

In this configuration, the Inverter is the component that generates the most heat and is usually the first to wear out, especially in hot, dusty environments.  We’ve already mentioned that heat makes electronic components and other machinery wear out faster.  To reduce the consequences of the heat they produce, the manufacturers add fans to keep the devices cooler.  Unfortunately, in places like Africa or the Middle East, these fans draw dust into the machine or component, thereby wearing them out even faster.

We have been successful, however, to create an alternative setup where the entire system runs low-voltage, DC current and cool.

Choosing a Solar Battery

There are several battery types that can be used for a solar energy system.  Here are some of the more common ones and their differences:

1. Lithium-Ion Batteries:
   • Lithium-ion batteries are versatile and widely used in various applications, including smaller microgrids.
   • They offer high energy density, allowing for efficient use of space.
   • Lithium-ion batteries have a longer lifespan compared to lead-acid batteries and require minimal maintenance.
   • They can handle deep discharges and provide good efficiency.
   • While they have a higher upfront cost, the decreasing prices of lithium-ion batteries have made them more accessible for smaller microgrids.
   • Their compact size and lightweight nature make them suitable for installations with space constraints.
2. Lead-Carbon Batteries:
   • Lead-carbon batteries combine the benefits of lead-acid and carbon technologies.
   • They are an improved version of traditional lead-acid batteries and are suitable for small to medium-sized microgrids.
   • Lead-carbon batteries offer higher cycling capabilities, longer lifespan, and increased charge acceptance compared to standard lead-acid batteries.
   • They are more resistant to sulfation, which can extend their overall lifespan.
   • Lead-carbon batteries perform better under partial state of charge (PSOC) conditions, which is common in renewable energy systems.
   • While they may have a slightly higher upfront cost compared to traditional lead-acid batteries, their improved performance and longer lifespan can make them a cost-effective choice in the long run.
3.  Absorbent Glass Mat (AGM) Batteries:
   • AGM batteries are a type of sealed lead-acid battery that uses a fiberglass mat between the plates to hold the electrolyte.
   • They are maintenance-free, as the design eliminates the need to add water or check the electrolyte levels.
   • AGM batteries offer good resistance to vibration and shock, making them suitable for mobile or off-grid applications.
   • They have a relatively low self-discharge rate and can provide high currents when needed.
   • AGM batteries are generally more expensive than traditional flooded lead-acid batteries but provide better performance and durability.

4. Lithium Iron Phosphate (LiFePO4) Batteries:

   • LiFePO4 batteries, also known as LFP batteries, are a type of lithium-ion battery chemistry.
   • They are highly regarded for their long lifespan, typically lasting over 10 years.
   • LiFePO4 batteries have excellent thermal stability and are less prone to thermal runaway or fire hazards compared to other lithium-ion chemistries.
   • They provide a high number of charge-discharge cycles, making them suitable for long-term use.
   • LiFePO4 batteries have a high energy density, allowing for compact and lightweight designs.
   • They can handle high discharge rates, making them ideal for applications that require high power output.

Of the two most feasible choices in a typical remote location, there are lithium-ion and lithium iron phosphate.  When comparing lithium-ion (Li-ion) batteries and lithium iron phosphate (LiFePO4) batteries for use in solar energy systems, there are several factors to consider:

1. Energy Density: Li-ion batteries generally have higher energy density compared to LiFePO4 batteries. This means that for a given weight or volume, Li-ion batteries can store more energy. Higher energy density is advantageous when space or weight is a concern.

2. Cycle Life: LiFePO4 batteries typically have a longer cycle life compared to Li-ion batteries. A cycle refers to a complete charge-discharge cycle. LiFePO4 batteries can endure a larger number of cycles before experiencing significant capacity degradation. This makes them more suitable for applications that require frequent and deep cycling, such as solar energy systems.

3. Safety: LiFePO4 batteries are considered safer than Li-ion batteries. LiFePO4 chemistry is more stable and less prone to thermal runaway or spontaneous combustion. They are less sensitive to high temperatures, overcharging, and physical damage, making them a safer choice for applications where safety is a priority.

4. Cost: Li-ion batteries are generally more affordable than LiFePO4 batteries, primarily due to the difference in materials used. LiFePO4 batteries require a higher quantity of raw materials, including iron, which can contribute to their higher cost.

5. Efficiency: Both Li-ion and LiFePO4 batteries have high charge and discharge efficiencies. However, LiFePO4 batteries typically exhibit slightly higher round-trip efficiency (energy efficiency of charge-discharge cycles) compared to Li-ion batteries, resulting in less energy loss during operation.

6. Operating Temperature Range: Li-ion batteries can operate over a wider temperature range compared to LiFePO4 batteries. LiFePO4 batteries have a narrower temperature range in which they perform optimally. Extreme temperatures can affect the performance and longevity of both battery types, but LiFePO4 batteries are more sensitive to high temperatures.

In summary, Li-ion batteries offer higher energy density and lower cost, making them a good choice for applications where space and budget are significant considerations. LiFePO4 batteries, on the other hand, provide longer cycle life, improved safety, and better performance in extreme temperatures, making them suitable for applications that require frequent deep cycling, safety, and reliability. Ultimately, the choice between the two depends on the specific requirements and priorities of the solar energy system.

For these reasons, our first choice would be LiFeP04 batteries:  they are safer, they last longer, more efficient than the Lithium-Ion batteries.  We feel that these tradeoffs make the small extra cost worthwhile.