What Is Inverter Bypass Mode? (Great Feature)

Some inverters and, more specifically, Uninterruptible Power Supply (UPS) inverters must run continuously to supply alternating current of stable voltage and current strength to the connected AC loads. Such an inverter system cannot remain operational indefinitely and will break down or require maintenance from time to time.

Inverter Bypass Mode allows the AC grid power to bypass the inverter and directly power the connected AC loads if the inverter breaks down or requires maintenance. An automatic transfer of power from the grid AC will bypass the inverter when it experiences an internal failure.

Installing a bypass switch or inverter with a bypass mode function is recommended in grid-tied situations. In an off-grid solar-powered system, a bypass switch or bypass mode will be redundant as the inverter will function for as long as the battery bank is sufficiently charged.

The types of bypass switches available are:

  • Static bypass switch
  • External maintenance bypass switch

Let’s look at the differences between these two types of bypass switches and how to bypass mode on inverters works.

Inverter With Bypass Mode
Inverter With Bypass Mode

How Does A Static Bypass On A UPS Inverter Work?

An Uninterruptible Power Supply (UPS Inverter) is linked to a battery bank from where it draws direct current (DC) and converts it to alternating current (AC), which is stable and available for as long as the battery charge remains sufficient.

The battery bank is charged from the grid AC power supply via a battery charger. The function of the UPS is to feed the AC loads with the power of a constant voltage and operating frequency and to ensure that the power supply to the connected loads is not suddenly disrupted.

UPS Inverters also fail eventually due to heat degradation of the circuitry and components of the inverter. UPS failure is negated by installing a static bypass switch either in the UPS or as a separate switch.

Voltage Detection

If the UPS inverter fails, the static bypass switch will detect the voltage drop and instantaneously switch to the grid AC power supply. This will ensure continuity of power to the connected AC loads and allow time for the UPS Inverter to be replaced or repaired.

A static bypass switch senses the continuity of the AC supply of the UPS and will switch to AC-grid power when it detects an interruption in supply from the UPS. This ensures that the connected AC loads can continue running without any disruption.

The static bypass switch must not be confused with the maintenance bypass switch, which is engaged manually when the UPS Inverter has to be maintained or replaced.

Why Does An Inverter need To Have A Bypass Mode?

Grid-tied inverters need to have a static bypass switch as part of the inverter assembly to enable the AC-loads to keep running on grid power in the event of a failure of the inverter or backup battery.

There is no backup to the power stored in the battery bank in an off-grid power supply system. The battery bank is charged via solar panels, wind power generators, or a backup generator.

Still, if the battery bank is depleted or the inverter breaks down, there is no redundancy power available to maintain the power supply to the AC loads.

In a grid-tied system, the power grid is the backup power source if the inverter becomes defective or the battery is depleted beyond the maximum depth of discharge.

The inverter can switch over to bypass mode when it detects that the inverter fails and routes grid AC directly to the distribution panel and the AC loads.

Repair or Replace

This bypass mode operation will allow the inverter to be repaired or replaced or for the battery charge to be replenished to a point where the inverter can function again. The battery technology determines the depth of discharge possible.

Lead-acid batteries should not be discharged lower than 50% of maximum charge capacity as this will cause damage to the battery chemistry and significantly reduce the number of recharge cycles of the battery.

Modern Lithium-Ion batteries can continue to operate to a much lower depth of discharge level without any detrimental effect on the battery chemistry.

They can be fast-charged back to operational levels and last as much as ten times longer than conventional lead-acid batteries.

Planning Your Inverter Installation Features

The principle of building redundancy into your power supply system ensures that power supply continuity can be maintained when the primary power supply system fails. For a grid-tied Uninterrupted Power Supply Inverter system, it is imperative that the inverter is fitted with a static bypass switch.

UPS systems are designed to filter grid AC and ensure that connected AC loads do not suffer from sudden power loss. The UPS batteries are charged via a rectifier circuit to maintain the battery state of charge within the operational range.

The UPS inverter draws direct current from the UPS batteries and converts it to AC power of uniform voltage and sufficient current to power the connected AC loads. If the inverter battery or the inverter components fail, a static bypass switch directly connects the AC loads to the AC grid power supply.

Bypass Mode Gives Flexibility

It does mean that the AC loads may be subjected to the variations and instabilities of the grid power, but this is preferable to the complete loss of power. The inverter can be repaired or replaced in static bypass mode, or the UPS battery can be recharged.

A bypass mode is a form of redundancy in that the grid AC can be switched on in the event that the UPS supplied AC is interrupted. This maintains the functionality of the connected AC appliances and devices, allowing them to be shut down in a controlled manner.

The computer systems for banks and communication centers will have several layers of redundancy to ensure that the systems that require continuous power supply can remain unaffected if one or more of the power supply sources are affected.

Inverters designed for such applications have static bypass switches incorporated into the system design to enable continuity of supply to grid-tied inverter power systems.

References:

General Solar Panel FAQ

What Problems Do Solar Panels Solve?

In environmental terms, solar panels can potentially solve a handful of problems, including;
1. Air pollution
2. Water pollution
3. Greenhouse gases
4. Reduction in fossil fuel use

For individuals, solar energy allows you to become completely self-sufficient when it comes to your electricity needs and can save you a lot of money in the long run.

What Are 3 Important Uses Of Solar Panels?

The three most important uses of solar panels are;
1. Solar electricity. This can be used to power almost any appliance in your home, including TVs, computers, and fridges.
2. Lighting. In addition to the use of low-power, LED lightbulbs, solar panels can provide an efficient, low-cost, and environmentally friendly way to provide lighting to homes. 
3. Portable solar. In our modern, always-connected lives, our phones, tablets, and computers are almost always with us, and all run on batteries. Portable PV chargers can help keep our batteries topped up no matter where we are, as long as there is some sun to charge them.

Do solar panels give you free electricity?

Once the cost of the array is paid in full, the energy it produces is free. There are ongoing maintenance costs, too, such as annual panel cleaning, etc. 

How much will my electric bill be with solar panels?

Suppose your solar array includes a solar battery backup system, and it is large enough to fully cover your energy usage per day. In that case, your monthly electric bill will be next to zero dollars, even with a grid-tied system. 

If your solar array does not include a solar battery backup system, then at night, your house or business will use grid electricity. That cost will vary but expect to pay from 1/3-2/3 of your average electric bill, and that cost will fluctuate seasonally. 

Do you save money with solar panels?

The simple answer is, Yes, you save money with solar panels. There is an initial upfront cost, but since solar panels are warrantied for 25 years, you will save money over time. You will also begin to see monthly savings in energy bills, but there are other ways that solar panels pay you back. Those include:
1. Adding value to your home or commercial building 
2. Monthly decreases in energy costs
3. The ability to add more energy appliances without increased monthly costs
4. The potential for tax credits for going solar

Can solar panels power a house 24-7?

Most definitely! Solar panels can certainly power a house 24-7, with the addition of a high-quality inverter and a suitable battery bank, of course. To power, a house under normal usage will require a massive solar array, though, and there will be a very expensive initial financial outlay.

Do I need to tell my energy supplier I have solar panels?

This depends on where you live, but in most cases, it’s not necessary to inform your energy supplier that you have solar panels. That said, you may be producing excess power with your solar system, in which case you may be able to sell that excess power back to energy companies.

In this case, you’ll naturally need to be in contact with them. 

What Are Solar Cells Known as and Why?

Solar cells are also called photovoltaic (PV) cells. They are called so because the term ‘photovoltaic’ literally means light i.e. photo and electricity i.e. voltaic.

These cells generate electricity through the photovoltaic effect. This effect basically causes the generation of free electrons from the semiconducting silicon material of the solar panel when sunlight hits its surface.

What Type of Solar Panels Are Most Efficient and Why?

There are currently three types of solar panels available in the market that are:
1. Monocrystalline
2. Polycrystalline
3. Thin-filmed

Among these, monocrystalline solar panels are known to be the most efficient among all others.

Does heat enter your home through the roof?

Absolutely. Heat enters your home through your roof, and on a hot day your attic can get up to 150 degrees Fahrenheit or more. Through conduction, heat from the sun warms your roof which then warms your attic and the rest of your home.

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