A Powerwall home energy storage wall is a back-up energy system that is capable of storing large amounts of energy for certain emergencies. This Powerwall home energy storage wall is a simple to use and long-lasting energy storage system. Not only can it be used to power appliances such as lights and refrigerators in the event of a power outage, but it can also help to reduce dependence on the grid and achieve partial self-sufficiency, saving on electricity costs.
Nowadays, more and more DIYers are experimenting with the residential energy storage aspect. And as a kind of energy storage system with higher selling price but lower production cost, more and more people have started to try DIY Powerwall home energy storage wall.
1. How to DIY Powerwall home energy storage wall
1.1 Determine the voltage of the energy storage wall
Before making a homemade Powerwall home energy storage wall, we first need to estimate the maximum current of the system, as a way to calculate the maximum voltage of the battery cells, and select the most suitable battery according to this data.
Secondly, another important reference for determining the rated voltage of the energy storage wall is the input voltage of the inverter. This kind of home-based energy storage wall generally speaking needs to be installed with an inverter, and then the AC power converted by the inverter will be used to supply energy to the home appliances. Therefore, the input voltage of the inverter used largely determines the amount of voltage of that energy storage system.
Although it is said that the higher the voltage of the energy storage wall, the less stress the parts of the system have to endure and the smaller the wires that are connected to the components. However, in addition to the energy storage system that needs to be taken into account, we also need to consider the cost of components such as the BMS, inverter, charge controller, and so on. Therefore, various factors need to be considered when choosing the voltage of the energy storage wall.
1.2 Connecting batteries together
1.2.1 Two ways to combine batteries to form a battery pack
There are two ways to connect the batteries needed for homemade together, and the difference between the two lies in whether the batteries are connected to form a battery pack by means of welding.
One is to connect a fuse protruding from the positive terminal to the negative terminal, and then connect the individual cells to the busbar through this fuse. By repeating the above steps, it is possible to connect the cells to form a battery pack. The battery pack is then soldered to the copper tube by means of soldering.
The second way is to connect the fuse of each battery to a wire with a screw terminal on the end, and then solder the screw terminal to the copper tube. This direct connection of the cells to the batteries by means of screw terminals rather than soldering will provide convenience in the event that a single battery needs to be replaced at a later date.
1.2.2 Material selection for connecting battery packs to make consumables
When using copper busbars, the second way of simple connection cannot be realized. Therefore, if you want to avoid soldering and directly assemble the cells to form a battery pack, you can use aluminum strips.
For reasons of ease of disassembly and size of space, the wires needed to connect the batteries can be chosen from a slightly smaller model. It is more convenient to disassemble and strip the wires when making your own. At the same time, its size is smaller, more suitable for use in the home environment
1.3 Making the overall framework
Generally considering the avoidance of fire caused by electrical appliances failure, the frame of the homemade Powerwall home energy storage wall should generally choose non-flammable materials. The specific structure and size of the frame mainly depends on the specific power of the energy storage wall and the specific number of battery packs.
Generally speaking, each battery parallel group needs to be separated by a frame structure. Firstly, the aluminium busbars have to be installed inside the frame, then the battery packs have to be connected to the busbars, and it is better to balance the capacity of each battery pack in the frame while completing this step. Finally, the outermost layer of the frame structure is installed.
1.4 Installation of inverters and charge controllers
The main function of the inverter is to convert DC power into AC power. For some industrial workshops that can be powered directly by DC power, it is not necessary to install an inverter or not. But for the Powerwall energy storage wall for home use, the installation of the inverter is very necessary because most of the home appliances use AC power supply.
Secondly, as the DIY energy storage wall may require a higher current when charging, but in order to avoid damaging the battery pack and causing a fire. The presence of a charge controller is very necessary. It is worth noting that before installing the charge controller, you need to make sure that the two are configured correctly for compatibility: first, check that the battery chemistry supported by the charge controller is compatible with the batteries used in your homemade. Second, check the current setting of the charge controller to avoid over or under setting the current, causing damage to the battery pack or slow charging.
2.What type of battery do you need to choose for DIY Powerwall home energy storages
2.1 18650 lithium battery
18650 battery is the most common type of battery used to make energy storage wall. Its advantage is that it is small and inexpensive, which is suitable for the requirements of cost saving when DIY energy storage wall.
2.2 Lithium iron phosphate battery
Lithium iron phosphate battery is a kind of lithium ion battery. Its operating voltage is lower compared to 18650 batteries, so while choosing to use lithium iron phosphate batteries means that more batteries are needed to maintain the same voltage of the energy storage wall. Although this point raises the cost to some extent.
However, it is worth noting that for some sizes of systems, such as 12-volt energy storage systems. Selection of lithium iron phosphate battery will be very suitable, can improve the operating efficiency and service life of the system.
3. DIY Powerwall home energy storage device need to pay attention to what issues?
3.1 Do I need to install BMS and how to install BMS?
BMS, also known as battery management system. The main purpose within the system is to monitor and manage the performance status of the battery pack. Its operation principle is connected between the negative terminal of the battery pack and the load, after the negative terminal of the battery enters the BMS, then from the BMS directly into the load.
While the current is constantly flowing, the BMS can keep it passing at the rated current level at all times, thus keeping the battery pack safe. In terms of installation, it is usually necessary to set the rated current value of the BMS a little on the high side for the system to operate properly.
3.2 How much can a DIY Powerwall home storage wall save?
The selling price of Tesla’s Powerwall home energy storage wall depends on the specific power which is the number of lithium-ion batteries, generally speaking, a 5kwh energy storage powerwall for around $700, and a 10kwh powerwall for around $1,300.
Due to the simplicity of the construction of the wall, the price of the required parts is also lower, for example, you can use lithium-ion batteries removed from your laptop and buy the whole frame at a yard sale. This means that you can save about seventy percent of the cost of a successful homemade energy storage wall.
To summarize
A DIY home-based Powerwall energy storage wall can save you a lot of money. However, before you start making your own, you first need to calculate the right voltage, and then prepare the raw materials such as batteries, bus bars, frames, and other supporting components such as inverters, charge controllers, and BMS.
After making all the preparations, then start the assembly. Secondly, as it involves part of the knowledge of electrician, learn the related knowledge properly before the DIY starts, I believe this can ensure your DIY process smoother. Finally, the DIY process needs to maintain a professional and rigorous attitude to ensure the safety of your life and property.
