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Best 2020 solar batteries for Africa: 2 top-rated picks from our experts
The most commonly sold solar batteries by chemistry type are:
1. NMC - Nickel Manganese Cobalt. These are typically found in Tesla Firewall and Tesvolt batteries. NMC batteries have the longest life of up to 30 years operation.
2. LiFePO- Lithium Ferrous (Iron) Phosphate. These batteries are found in the following brands: BYD and Simpliphi. LiFePO batteries last 10-20 years, depending on the manufacture.
3. Lead Acid batteries. These are the most commonly found batteries in Africa and include AGM, Gel, OPZV. These batteries can be found in Rolls Surette or Trojan. Lifespan can be as much as 10 years, but depends heavily on the manufacture.
There are 5 factors to consider when buying a battery. This article will discuss each of these factors.
1. Heat. How does the battery function in temperatures above 25C / 72F?
2. Longevity. How many cycles does the battery have, measured in Depth of Discharge DoD?
3. Price. How much does the battery cost per kWh, and for how many years?
4. Environmental foot print. What was the environmental impact from production and how easy is it to recycle?
5. Performance. How much of the battery is usable and what is the efficiency of the battery?
To LiFePO or not to LiFePO, that is the question
LiFePO are a high quality, endurance battery, with low environmental impact on production and on end-of-life recycling. Unlike other batteries that require mining of rare earths and minerals, and rely on child labor, LiFePO has the cleanest environmental bill of all the batteries out on the market.
We recommend BYD for the LiFePO brand.
Reasons: BYD is one of the largest battery makers in the world, with a solid track record. The BYD LiFePO has up to 8,000 cycles at Depth of Discharge (DoD) at 90%. What this means is that the battery can be nearly fully discharged without being damaged. The battery can safely operate up to 50C without being damaged, making the BYD LiFePO one of the safest batteries to operate, especially in hot climates found in Sub Saharan and continental Africa.
sizing a system: For off-grid solar power systems, a certain percentage of total power is consumed during the day, generated by the solar panels, and a certain percentage at night, which will come from the batteries. It is smart to make sure your system has more than enough power so that you aren't ever running out and having blackouts at night. For long term value, it's best to have battery systems have one cycle of discharging before recharging lasting 1-3 days. It's easier on your system and means that your equipment will last longer.
Expanding the system tomorrow impacts the design today
If your goal is to expand the system to a larger size in the future by adding equipment rather than replacing equipment, then these are some important question you should ask:
Will the system use heavy machinery, like a maize mill or air conditioners, in future, requiring a 3-phase system?
In how many years will the system expand? What size will it ultimately be?
Is this strictly an off-grid system, or will it take a blend of power from sources like the grid and generators, with power generated by solar the top priority?
What is the best battery for future expansion?
NMC conveniently couples 1x1 battery to inverter, whereas the LiFePO requires 2x the amount of battery to inverter. So as households start adding appliances, and peak time increases which is the time of day when everyone has everything plugged in, the NMC system would only require additional inverters to meet growing demand, whereas the LiFePO system would require purchasing both batteries and inverters, making this less cost effective.
The Tesvolt battery allows for more batteries to be joined on a single string connected to an inverter, whereas LiFePO has restrictions on how many batteries can be on a string, creating some limitations on LiFePO bigger systems.
We recommend Tesvolt as the best value for this class of battery. It has been designed to integrate seamlessly with SMA. Tesvolt is made with Samsung battery cells and is produced in Germany.
Lead Acid batteries are not a good option for larger scale systems. They are combustible, have short lifespans, don't do well in heat, take up a tremendous amount of space, are bad for the environment, and in large numbers, create a nightmare for wiring.
What is the highest performing battery?
In terms of longevity, NMC is the clear winner. It can be fully discharged 100%, and still gives out 8,000 cycles. LiFePO batteries has an 80% maximum discharge, meaning you can only ever access 80% of available battery capacity, which requires you to buy more battery than you can actually use. The LiFePO at 80% gives 6,000 cycles.
On the other hand, LiFePO has a fast recharge time and a 99% efficient recharge process, which means less wasted electricity. It also has a low rate of self-discharge, which means a long shelf life of up to a year between charges.
Which battery is better for the environment?
LiFePO, hands down wins this question. They are made of non-toxic materials, use commonly available materials including copper, iron, and graphite and contain no rare earth metals, making them an environmentally conscious choice. Less energy is consumed in mining and processing of materials. Phosphate salts are also less soluble than metal oxides, so they are less likely to leach into the environment. Disposal causes minimal harm. LiFePO is environmentally friendly compared to other batteries.
BYD is the world’s leading producer of rechargeable batteries. They have had financial support from Warren Buffet. They offer the “best value for the money” LiFePO battery on the market. Unlike nearly every LiFePO battery out there, the BYD can handle being fully discharged, often. BYD is one of the few batteries that is certified by SMA for ease of configuration and can last up to 20 years.
Conversely, the NMC battery
What is the better inverter for mini grid expansion?
SMA is the most versatile inverter on the market, offering smaller sized 3-phase systems for systems that intend to grow. SMA and the Tesvolt battery have integrated their smart technology seamlessly, making this inverter / battery combo one of the safest and highest performing on the market.
What's the safest battery?
LiFePO is a very stable battery, with not a lot of volatility compared to other batteries, making it the safest option. LiFePO can withstand cold, heat, collision, and mishandling during charging and discharging without risk of combustion.
Of course, if batteries and inverters are wired and stored correctly, in a locked frame, with cool atmospheric temperatures in a well-ventilated and sealed area without dust or rodents, then all of these battery options will be safe. LiFePO is the safest option when there are unexpected environments or events, like a spike in exterior temperature, a collision or short circuit.
What is the best entry-level product?
If you want to test the market, aren't sure if you will expand the system in the future, and want a low cost system that gets you in the door, then the Lead Acid battery and Victron inverter system are the best combination. The batteries will give a solid 5-7 years of life, if stored in a well ventilated, dust-free, and cool environment, and by that time, you can decide your next steps. The solar system should last 30 years, the inverters at least 10 years, and you can extract much of the value within a short time, without spending a lot.
How should I store my equipment?
It is best to have a well ventilated, cool, and dust-free environment for all equipment. LiFePO and NMC batteries can safely operate up to 50C/ 122F, while lead acid batteries start having permanent damage after 25C/ 77F. If the system is large, a containerized system may be the best option to control the atmosphere surrounding the equipment, including a humidifier to prevent static, ventilation, and in some cases, air conditioning.
Security is often an issue. We recommend having steel, lockable, frames for the equipment. Most equipment is very heavy, so when they are locked together, it makes it difficult for a "grab and go."