Battery Technologies for Off-Grid Living
There are so many battery technologies out in the marketplace, and it is highly likely between me writing this and you reading it there will be another new fandangled world’s best battery that has hit the market.
What Elon Musk has done with Tesla is to create a market awareness of wanting to install home battery storage and reduce our impact on the environment from burning fossil fuels. This has been fantastic for raising the level of awareness.
Is installing home battery storage actually the best thing for the environment though?
As any good permaculture teacher will tell you “It all depends on the situation.”
My experience with batteries is that all the technologies have a place and purpose; it’s about choosing what’s right for you and your situation.
It’s about choosing the right tool for the job and understanding the capabilities of that device. Not choosing the correct tool for the job can end up with a broken machine!
This week I got the inside on the Tesla power wall training I attended about installing home battery storage from the distributor of Tesla powerwall in Australia. It was a fascinating look on what can be done with the technology and it’s limitations.
The three top batteries sold around the world for battery storage are Lithium, Lead Acid, and Nickel-Iron Cells. Australia is currently the largest installer of nickel-iron cells around the world for stand alone solar applications.
Let’s start with the number one selling battery worldwide the Lead Acid Battery.
Lead Acid Batteries
Lead Acid cells have been the biggest selling batteries for home energy storage as they have been the most cost efficient and simple cell to use. Being the battery of choice for cars has helped bring down the cost of production. A lead-acid battery is made up of 2-volt cells. Your car battery, for example, will have six 2-volt cells joined in series, and that will give you a 12-volt battery. The most common thing in your car battery that fails will be a cell, and unfortunately, you can’t replace the one cell. The reason in larger systems you get individual cells is a) if one fails you can replace the one cell and, b) they are easier to move around, as lead has substantial weight when you start putting large systems together.
You can get a lead acid battery to last 25 years and yes you can build a system out of them using 12-volt car batteries.
The key to getting them to last a long time is running loads like lights, computers, fans, TVs, energy efficient fridges, and avoiding items that have a significant power draw at a high speed like kettles, toasters, ovens, microwaves, irons, and electric hot water systems. A good rule of thumb is, if it heats or cools it will want lots of energy fast.
If you’re going off-grid the majority of the power-hungry devices used for heating can be sorted out by installing a fireplace and by using landscaping (good design) to cool your dwelling too. Most off-grid systems will have a generator of some kind for backup. It is best to run any of the energy hungry appliances directly from your generator as it will make everything last longer. If you have the grid available you can use the network as your backup as running massive loads directly from the grid will save your batteries.
The key to getting your lead acid cells to last is to keep them well charged and to only use 30% of their capacity. Use only light loads and understand how your appliances work. With this knowledge and application a good lead acid set will last as long as your solar panels.
Nickel-iron and Nickel-cadmium cells both last a very long time. Nickel-cadmium cells are not that attractive as one must deal with the cadmium waste disposal problem at the end of their life cycle. Nickel-iron, on the other hand, is Nickel and Iron; the NiFe cells name comes from the periodic table. The electrolyte in a NiFe cell is alkaline-based potash, which is just distilled water and potassium hydroxide. This is a commonly used plant fertilizer. Your biggest decision when getting rid of the electrolyte once neutralized is deciding where you are going to grow your pumpkins and Jerusalem Artichokes. They both love potash.
These batteries are very robust, and you can use anything on them. They will not be damaged by overcharging or undercharging. They are in my opinion one of the world’s most environmentally friendly battery on the market and one of the best all-rounder cells to use in a home storage system.
The downside to these cells is they off-gas hydrogen so it’s important to keep them in a well-ventilated space where they will not create a buildup of hydrogen. You are required to top them up with distilled water on average about 8-10 times a year depending on how hard you use them. The biggest problem people have with them is the combination of the right technology with regards to inverters and solar charge controllers.
Lithium’s popularity has taken off, especially with the help of Elon Musk’s passion for taking over the world with solar-powered electric cars.
Lithium is a battery that is light and energy dense. It is what has changed smart-phones, cameras, electric vehicles and anything that is a considered a handheld device. Lithium is ideal for all of these uses.
The most important thing to get right with lithium is the BMS (Battery Management System), and that there have been no faults in the manufacturing process.
Check out some fun and educational videos on exploding phones here. (Lithium Batteries)
Most of the handheld devices we own and use have been designed in such a way that before they get to the dangerous stage of battery failure we are up for a new device anyway. One of the issue’s I see with using lithium in home energy storage is in having the lithium battery permanently connected to a charger such as your solar panels on your house. If the BMS fails it will soon overcharge the batteries, and you could potentially have an explosion. A 7kWh power-wall will have a very different bang to a smart-phone battery.
It’s true that lithium batteries have a range of protective features to prevent this and using it in parallel with the grid is one of those essential protective features. Most lithium manufacturers will not allow their batteries to be used completely standalone without the grid at this point in time. There are also lots of brands of lithium available other than the ‘power wall’.
Lithium is an ideal technology for running light loads similar to the lead acid batteries, such as lights, TVs, energy efficient fridges and so on. It’s good for use in units, apartments, town-houses and in places where the grid is available and you can rewire your home only to run what I call your critical loads. This will make it last a lot longer and have some environmental benefit from installing it.
If you use a lithium battery and run ovens, air conditioners, kettles/jugs and heavy loads, you will be buying a new battery before it ever pays back the embodied energy in its creation, or your bank account.
Currently very little lithium is recycled due to the cost of doing so. This is the reason I call it the plastic bag of the battery world.
The best thing you can do for yourself and the environment is to reduce your energy demand. It will save you money straight away, reduce the use of fossil fuels and when putting in a home solar system with batteries you will be installing a smaller system, as you don’t have a large load to support.
Check out this video to help you reduce your energy demand for free.
To learn more about how to take control of your energy requirements, you can attend a hands-on workshop or subscribe to our YouTube channel for videos to help you on your journey.
Mike Haydon is running a 2 day workshop in our Greening the Desert Site in October 2018 , link below for more information :