Why Does My Inverter Keep Shutting Off?

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Inverters are designed to convert the direct current (DC) provided by a solar array or battery bank into alternating current (AC) for powering AC loads or feeding the AC into the power grid.

Inverters are designed with shut-off features to prevent damage to the battery bank or unsafe conditions in the power grid or overheating, low or high voltage input, or too-high power demand. The inverter has an LCD, error lights, and an audible alarm to signal the shutdown causes.

An inverter is designed to shut down or, in extreme situations, before any damage can be done to the input or output components of the system: The reasons for shutdown may be due to:

  • Grid power outage
  • Battery state of charge too low
  • Over or Under Voltage condition on inverter input
  • Inverter overheating due to being overloaded with AC loads
  • Inverter overheating due to cooling fan failure
  • Inverter component failure

Let’s review all the potential reasons your inverter may be shutting down.

Repairing A Solar Inverter
Repairing A Solar Inverter

Inverter Shutting Down Continually – Potential Reasons

Inverters are the sacrificial components in grid-tied and off-grid solar power systems. The inverter trip is due to a condition that may cause damage upstream or downstream or when the power input is unstable or interrupted.

Inverters work very hard in converting direct current from a solar array or battery bank to alternating current, and as a result, they generate heat that will deteriorate the components and circuitry over time, leading to a lifespan of typically ten years.

If your inverter is continuously shutting down, check for one or more of the following conditions:

  1. Sufficient sunlight to power the inverters as they can only work when they receive sufficient DC input current and voltage to power the connected AC loads. If the solar energy generated by the solar panels is insufficient to charge the battery bank or allow the inverter to generate AC compliant with the grid input parameters, the inverter will shut down.

The number of Productive Solar Hours per day in the US averages about five hours. Look up the PSH for your area and use this number to calculate how much solar power can be generated per day.

  1. Grid Power Supply Outage – In a grid power outage, the inverter must shut down to stop AC from being fed into the grid and endangering the technicians working to repair the grid supply.
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The inverter continuously senses the grid power’s presence by measuring the grid’s voltage and frequency and adjusting the AC generated to match. The inverter must be UL certified to signify that it can shut down in the event of a power outage.

  1. The battery back may be discharged to a state of discharge that is below the programmed disconnect voltage. Lead-acid batteries should not be discharged below 50% of their maximum state of charge. Li-ion batteries can be discharged to almost 0% SOC, but keeping the SOC between 20% and 80% is recommended for the best battery life and recharge time.
  1. An inverter failure is seldom without prior warning. The inverter will run a self-test sequence when switched on to sense abnormal input conditions or an overload on the output side. Modern inverters are fitted with liquid crystal displays that indicate the error code.

A red LED will indicate an error mode and be accompanied by an audible beeping signal. The user can correct most such error messages, but in case of the inverter fails, it will have to be repaired or replaced.

  1. An overload of the inverter on the AC output side is the most likely cause of the inverter shutting down. Check that the sum of the power demand of the appliances connected to the inverter does not exceed 80% of the maximum rated output.
  1. The inverter may also shut down when it senses that the load demand on the output side is too high and will cause damage to the connected AC loads. Over and under-voltage protection on the inverter’s output side is required to protect the connected AC appliances from damage.
  1. Overheating the inverter components and circuitry will also result in a shutdown to prevent the inverter from burning out. The inverter cooling fans running continuously or becoming noisy is a sign that the inverter is overheating or overloading.

Check that the cooling fans’ air intakes are not blocked with dust and lint and that the fan blades are clean and running quietly. Ensure that the inverter has sufficient space around the heat sink housing to dissipate heat and is not close to other heat sources.

  1. Poor cable connections between the battery bank and the inverter or between the solar array and the inverter will also result in a shutdown. Cables of sufficient gauge must be selected and must be as short as possible to limit voltage drop.
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Inverters are designed to shut down to protect the entire system from damage or unsafe conditions. Most household fires have their origin in failed electrical installations, and inverters that fail to shut down will overheat and may lead to a short circuit.

If your inverter continually keeps shutting down and you cannot find the root cause contact the installer or a qualified electrician to investigate the installation and test the inverter.

The risk of electrocution with an inverter is very high, and the current is sufficient to cause a fatal shock.

Continual Inverter Shut-Down Is A Protection Mode

An inverter is a central point connecting the DC power source to the AC loads. DC power supply can be a battery bank, solar panel array, wind power generator, or hydropower generator. All these DC power sources are variable in output as their ability to supply power is limited.

To protect them from damage due to voltage drops or spikes, the inverter senses their state of power supply and will shut down operation if:

  • The battery state of charge (SOC) or depth of discharge (DOD) drops too low;
  • When the sunlight intensity is insufficient to generate solar power from the panels;
  • When the wind speed drops too below the generator’s ability to generate enough wind power;
  • When the water flow is insufficient to drive the hydro-generator to produce hydropower.

The inverter also has built-in protection systems to protect it from overheating due to:

  • Insufficient cooling due to poor heat dissipation;
  • Cooling fans not providing sufficient cooling airflow;
  • Inverter overheating due to excessive AC load demand.

The inverter will shut down when it detects any overheating or overloading conditions. It may also shut down due to defective internal components. If your inverter fails to startup, there must be a valid reason.

Start by checking the DC inputs like the battery SOC or the cable connections. Then check the inverter cooling fans and whether there is sufficient cooling space around the inverter. Finally, check that you do not have too many AC loads connected to the inverter.

If all your checks fail to get the inverter going again, it may be that you have some internal damage. Have the inverter checked out by a qualified technician and repaired or replaced if it is beyond repair.


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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