Uninterrupted power supply (UPS) and inverter are both the devices used to support power supplies when the power outage happens. Is UPS the same as inverter? Which one is better for home/business use? Do I need a UPS or an inverter? If you have these questions, this post will offer you some help on understanding UPS vs inverter.
An inverter, or a power inverter, is a power electronic device that converts direct current (DC) to alternating current (AC). It can be used as either a standalone device capable of receiving power from DC sources such as solar power and battery, and converting it to AC supply, or a utility-interactive inverter being one part of a bigger circuit such as power supply unit or UPS. An inverter does not generate or store power, but it can be connected to power sources, generally batteries, to support power supplies.
Figure 1: Inverters for solar power system
UPS refers to uninterrupted power supply. A UPS is a hardware device that provides backup power source when there is a power failure of the primary power source or a significant power drop. A UPS system contains a number of components. For a basic UPS system, it contains batteries, a battery charger, an inverter and a transfer switch. In this basic UPS system, the inverter is used as the device to convert the DC to AC since the power from battery use DC current but it has to be distributed in the form of AC. More information about UPS is available in What Is Uninterruptible Power Supply or UPS.
Figure 2: Standard parts in a basic UPS system
After the brief introduction of the inverter and UPS above, you may have a basic knowledge of inverter and UPS concepts. The following chart will help you gain a better understanding of their differences by considering the various factors.
|Main function||Providing backup power supply for devices to work on smoothly||Converting DC to AC and storing power in the battery|
|Energy storage||Yes, includes built-in batteries and a charge controller||No, but many inverter modules can use external storage|
|Backup time||Power back up for short duration||Power back up for long duration|
|Changeover time||Around 10 milliseconds||Around 500 milliseconds|
|Connection||Connected to appliances requiring alternative power||Connected to batteries and appliances|
|Power input||Around 240-279 Vac||Around 170-270 Vac|
|Battery maintenance||No maintenance required||Requiring continuous maintenance|
|Circuitry sophistication||More sophisticated||Less sophisticated|
|Protection||Providing protection to load||No protection against line abnormalities provided|
|Price||More expensive||Less expensive|
|Application||For electronics application domestic or industrial use||For general electric application|
From the comparison chart, it can be seen that inverters have major drawbacks in terms of long changeover time and no protection to the load. Though the inverter can be also used as backup power supplies when combined with an energy storage system, it can not realize the seamless transition as a UPS does. While due to the more complicated circuit and considering the additional components and functions, a UPS is generally more expensive than an inverter.
Since both UPS and inverter have their merits, how to choose between them? Maybe you have got your answers after checking the comparison chart of UPS vs inverter difference above. There are factors such as costs, power requirements and protection, etc. for the product to be considered. To make it simpler, it all comes down to your backup requirements and the most important thing to be considered is the extended delays in the power supply.
If you have not deployed either of them, this section is for you. For large business and organization applications that have high requirements in the respective of power system reliability, there is no doubt to choose the device with minimal delay—UPS to ensure data security and profits. For home use, if you are wondering if an inverter can be used as UPS in order to save costs, the answer could be: It all depends. If using inverters for general domestic electric gadgets whose working doesn’t get affected by the long switching time, it is feasible. For example, for most home electric gadgets such as bulbs and TV, the delay is endurable. However, for those critical devices like computers, it is advised to use UPS instead in case of data loss.
Some may get worried about whether the inverter can cope with the power outage of the PC properly and intend to add a UPS. If you do not want to use PC on the main inverter but want to connect to a UPS, it is OK. But note that sometimes UPS units don’t work well with an inverter (like a traditional UPS and an outdated square/triangle wave output inverter), the sine waves are terrible consequences may occur. But if the inverter combined with UPS is a pure sine wave inverter and the UPS can handle the sine wave, it is reasonably practicable. For a better experience, you are recommended to call the inverter vendor and search for help from their technician staff.