Backup Power Solutions And Tips
What is backup power for?
What happens when the supply of electricity suddenly stops when you need it the most? Are you going to wait until the power comes back even if life was on the line? What is its cost? I kid you not, the cost of a power outage can be severe. Sometimes it can cost you your life. Who knows? Electrical power is that important to human life and we are so dependent on it. That is the reason why John Hanley invented the “Backup Power Supply” back in 1934.
The main use of a backup power supply is that you will be immune to all power outages and blackouts. You can simply work as usual even if there is no power supplied by the grid. You will not waste your time.
From 1932 till today, people have been using backup power systems for different purposes. Early days, backup power solutions are used for major locations where vital economic activities took place. But now there is some sort of battery backup power supply for homes.
What types of backup power solutions you can choose?
There are two major types of power backup systems based on the source of backup power.
As the name implies, generator-based backup power is supplied from a generator connected to the supply. In generator-based backup power supplies, the grid supply and the generator supply are separated by a switch called the changeover switch found in the main panel board. When the grid supply is absent, the system will automatically identify it. The backup generator will start automatically, and the changeover switch will switch to the generator supply.
The other type of backup power is the battery backup system. These are also known as energy storage systems (ESS). There are two types of battery backup systems based on how the batteries are charged.
- Charged by the utility grid
- Charged by renewable energy (Solar)
There is quite a difference between these two types. The power backup systems are charged by the incoming AC (Alternating Current) power from the utility grid. But the battery outlets give out and receive power as DC (Direct Current) power. Therefore, AC power taken in from the utility grid is converted to DC power using a rectifier. Then only the battery is charged using a solar charge controller. These types of backup systems are “Uninterrupted Power Supplies” or UPS power supplies.
The other type of battery backup system is the solar battery backup system. These types are usually used in both off-grid and grid-tied solar systems. For this type of backup power system, having a solar PV system at your home is necessary. When the electricity is generated by solar panels, it is initially consumed by household appliances. The excess energy generated by the solar panels is stored in the battery to use as a UPS power supply for home.
Inverter with batteries backup power Vs generator backup power supply, which one is better?
Considering the generator-based backup systems, a separate generator will start to run to provide the backup power in case of a power outage. The source of power for a generator is usually fossil fuel like diesel.
- Compared to other backup power methods, generators produce loud noise and waste smoke as byproducts.
- The waste smoke may hold harmful gases including carbon monoxide and Sulphur which is quite bad for human health and the environment as well.
- A generator requires a larger room to work. Since it has a lot of mechanical moving parts, wear and tear are high.
Therefore, routine maintenance is necessary for the continuous operation of the system.
Compared to generator backup power, battery backup power system is somewhat better. How?
- It requires lesser space
- It produces no noise at all when it supplies backup power.
- There will be no harmful gas emissions while supplying backup power.
- The batteries do not have any moving parts involving friction.
Therefore, the maintenance of the battery backup power system is minimal.
However, there is a difference between utility grid-powered and solar-powered battery backup systems. You can consider, utility grid-powered battery backup systems are somewhat like generator backup power systems. Let me tell you why.
Power is supplied to the utility grid by different generation methods. There are a lot of power plants using coal and other fossil fuel. Their generators in those power plants are like the ones we use for backup although the scale may be different. Noise pollution and air pollution are prevalent in that scenario as well.
In contrast, solar powered backup power systems are much more environmentally friendly and economical. Here is why.
- solar power is one of the cleanest sources of energy.
- Solar energy is completely free anywhere on earth.
- It does not emit any harmful gases, nor does it generate loud noises which may pollute the environment.
- It merely converts the sunlight into electricity.
- There are no byproducts.
- In solar-powered backup power systems, the batteries are charged by solar power.
Therefore, the batteries keep charging the daytime automatically. Sunlight is available anywhere on earth. There are no special structures or machines to produce solar power. It only requires a set of solar panels and a roof with sufficient space.
Usually, solar panels have a warranty period of over 20 years. The lifetime of solar panels is said to be close to 35 years. It requires truly little maintenance as well.
Comparing all three backup power systems, solar-powered backup power systems lead because of all these advantages it brings to the table.
Battery Backup is BETTER than Generator Backup
Which device is used for inverter with batteries backup of power system?
To put up a solar-powered battery backup system, you need a hybrid inverter or an off-grid inverter. The hybrid inverter connects to both the backup batteries and the grid supply. When the grid supply is present, a hybrid inverter can supply power to your home and the excess is sold to the grid. When there is a power outage, the hybrid inverter quickly switches to backup power. It will cut off the grid connection and supply the power only to your home.
An off-grid inverter has no connection to the grid at all. It only connects to your home. When the grid supply goes off, the backup power switches on and supplies the power to your home.
You need special circuitry to charge batteries in addition to the inverter. It is called the solar charge controller. It controls the inflow and outflow of power of the battery when it is charging and discharging. In hybrid inverters, this circuit is included inside the inverter itself. Therefore, you do not have to buy a separate solar charge controller. In the case of the off-grid inverter, you must buy a separate charge controller sometimes since that part is not included in most of the off-grid inverters found in the market. However, good brands include the charge controller inside the inverter itself.
Home Battery Backup System – Power Outage Demo
How to connect inverter batteries backup supply to power supply?
First, you must install solar panels on the roof. In installing solar panels, you must make sure that there is no shade falling onto the solar panels. It might reduce the generation. The DC cables from solar panels is directly connected to the external charge controller (in case of and off grid system) or the hybrid inverter. In case of a off grid system, the batteries are also connected to the external charge controller. In contrast, if you are using a hybrid inverter, you must connect the batteries to the hybrid inverter.
Inverter inverts the DC power signal to 400/230V AC power which we use in our day-to-day life. If you are using an off-grid system, that means your solar backup power system have no connections with the grid. However, it is particularly important to keep in mind to use an auto changeover switch to switch between the grid supply and the solar backup supply. Therefore, both the home mainline, the grid supply and solar backup power supply should be connected to the auto changeover switch.
In hybrid inverters, the changeover operation is happening inside the inverter itself. Therefore, the home main line and the grid supply should be connected to the hybrid inverter.
What size of inverter batteries backup power supply system do you need?
Before planning on installing a battery backup system, you need to identify what appliances should be powered and for how long you need the backup power. Therefore, you need to take extra care in sizing the batteries and the solar PV when designing the backup power system.
In designing a backup power system, firstly, you need to see what appliances you should power from your backup power system. You can add up the rated power of all those appliances and understand the power requirement for the backup power system. You must choose the size of the inverter based on the power requirement of the appliances.
Next, you must find out the time you need these appliances to be powered. For example, if you run a motor of a capacity of 1kW for 1 hour, you need 1kWh (unit) of energy. So, if you need to run this motor for 5 hours using backup power, you need a battery capacity of 5kWh right? No, it’s wrong. When sizing the battery, depth of discharge (DOD) comes into effect. We must take this DOD factor into account. For old AGM batteries, the depth of discharge is 50%. It means that you can discharge the battery only up to 50% of the total capacity. If you choose a battery of 5kWh with 50% DOD, you can only use 2.5kWh out of 5kWh from the battery. So, when sizing the battery, it’s better to find a battery with high DOD. But you must compromise with the cost at the same time.
How long your inverter batteries backup power system can work?
The backup time solely depends on the amount of power drawn from the batteries. If you run many appliances at the same time and fully load the inverter, the backup time will be short. However, if you reduce the load on the inverter, you will be able to extend the backup time longer.
For example, for a backup battery with capacity of 1kWh (41.8 Ah at 24V), you can run a 1kW load for half an hour considering the depth of discharge is 50% (as explained in the earlier point). When you increase the load to 2kW, you can understand that the backup time will be limited further to 15 minutes only.
The backup time is dependent on the battery life of the system per single charge. The battery life is solely based on the load put on the backup power system.
How many loading appliances can you run at once?
The number of appliances loaded to the battery backup system depends on the rated power of the power inverter. For example, 1kW inverter can output power only up to 1kW.
Therefore, you must take extra care to manage the appliances so that the sum of the total power of the appliances accumulates to 1kW or a little less than that. If you try to overload the inverter, it will surely trip by activating overload protection. You will not be able to run the inverter until you reduce the load on the inverter to the rated value or less than that.
Therefore, the number of appliances loaded to the inverter totally depends on the capacity of the inverter.
Tips for better using solar inverter batteries backup power system
Here are a few tips when you use a solar-powered backup power system. You must use the batteries occasionally. That means you must discharge the batteries even though they are not naturally discharged because of power outages. When the batteries are idle for a long time, the charge leaks out and the battery characteristics tend to change little by little. After some time, the battery may not be able to hold much energy in it. The solar panels also need cleaning at least once in six months. There will be dirt depositing on the solar panels over time reducing the amount of light traveling onto the solar cells. Because of this reason, the generation of solar panels might fall. It might take a longer time to charge the batteries as a result.
However, compared to other backup power systems, solar-powered backup power systems are the least to worry about because their maintenance is minimal.
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