How does an off-grid inverter work?

When buying a solar system, we find 3 extensive options: off-grid and grid-tied and hybrid inverters. We must choose a suitable system among them. This is because each type of system has its advantages and disadvantages. Our choice of a suitable solar inverter can greatly impact equipment efficiency, installation costs, etc. Next, let’s explore off-grid and grid-tied solar inverters.

Grid-Tied vs Off-Grid Solar inverter

Off-grid solar inverter

An off-grid inverter is, as the name implies, a solar inverter that is off the grid, meaning that it works alone and cannot work with the grid.The off-grid solar inverter draws energy from the battery, transforms it from DC to AC, and then outputs it as AC. In a hybrid system, the off-grid inverter can be used to create the grid. Then, to run most or all of the electricity, utilize a grid-tied inverter.

Advantages of off-grid solar systems.

1. Completely independent of the grid and can install in locations where access to the utility grid is not possible
2. In some distant places, off-grid solar systems may be less expensive than extending power lines.
3. Off-grid solar systems are energy self-sufficient, and power outages on the utility grid will not affect them.

Disadvantages of off-grid solar systems

1. They cost more
2. Batteries need to be powered continuously during the day and night
3. May require lifestyle changes to reduce energy consumption
4. May waste excess energy production
5. At night or on overcast days, you can’t rely on the grid.
6. Batteries require maintenance, have relatively short lifetimes, and degrade rapidly

Grid-tied solar inverter

Grid-tied inverters are designed to be linked to your home’s main power supply to supplement it. When solar energy is available, the system feeds it to your appliances. When there isn’t enough energy to go around, the system reverts to grid power.Grid-tied inverters work with the power source to deliver as much energy as possible. Their intelligent design knows when power is being provided and when it is not and synchronizes power delivery with grid power.

Advantages of Grid-tied Solar Inverters

1. Grid-Tied Solar inverter systems save more money because they do not require batteries and other equipment
2. Can sell excess power to utilities for additional revenue
3. Lower installation costs, no maintenance or replacement, higher efficiency
4. Net metering allows the power generated by the solar system to offset the energy used from the grid at night or on cloudy days
5. Can obtain backup power from the utility grid to prevent sudden power outages

Disadvantages of Grid-tied Solar Inverters systems

1. Your grid-tied system will automatically shut down during a grid outage and turn back on when power is restored if a grid failure causes a power loss.
2. Not completely grid-independent

How does a Grid-Tied Solar Inverters system work?

A grid-tied system works by allowing solar panels (via an inverter) to power your house. And the solar inverter will connect to the local utility grid to connect. The solar inverter will power your home load until the demand for electricity exceeds the supply. Then you will need to purchase some equipment, which includes:

Grid-tied inverter:

Regulates the power coming from your solar panels. The DC power brought in by your panels is converted into AC power that your appliances can use. Another type of inverter you might consider is a micro-inverter. Each solar panel has an inverter on the back of it. It can increase the amount of power converted to each panel. This is a good option if your panels are often in the shade. But micro inverters are, of course, more expensive.

Power meter:

Often called a net meter or bi-directional meter, this device can measure power in both directions from the grid to your home and vice versa. Calculate the electricity generated by the solar panels as well as the utility grid connection. Sometimes your local supplier will install one for free.

How do off-grid solar systems work?

If you desire or need to be totally self-contained from the local power system. Then a stand-alone solar option that allows you to be entirely off the grid is a good choice. In other words, your solar panels will allow you to be entirely self-sufficient in terms of energy. This power will transmit from your panels to a set of solar batteries that will pass through an off-grid inverter and directly into your home.If you want to install this system for your home, you must install some key equipment for your system to operate as a unit. This includes:

Solar charge controllers:

Also known as charge regulators, these controllers regulate the amount of power flowing to the solar cells. This is necessary to avoid harming the batteries by overcharging them. A suitable charge controller is critical to keeping the batteries healthy, ensuring the maximum life of the battery pack. If you have a battery-based inverter, it will most likely have an integrated charge controller.Battery pack: A battery pack is essentially a group of batteries connected. It stores the power generated by the panel. A battery pack is important unless you like to live in the dark after sunset.

DC Connection Switch:

All solar systems require AC and DC safety disconnects. An extra DC disconnect is built between the battery bank and the off-grid inverter for off-grid solar systems. It does use to interrupt the flow of electricity between these components. This is critical for preventative maintenance, troubleshooting, and electrical fires.

Off-grid inverter:

The solar charge controller and the battery bank both receive current from the solar panels. It is finally converted to AC power by the off-grid inverter. This regulates the current from the panel and converts it to AC for your equipment to use to turn on the power.

Backup generator:

If you live in a place that doesn’t see sunlight all year round. Then you’ll need to invest in a backup generator. Standby generators generally output AC power. AC power can be used through an inverter or converted to DC power and stored in the supply battery.

Conclusion

For most people, a grid-tied solar system is a safe and predictable investment for their business, farm, or house. A solar system connected to the grid has a faster payback and fewer components to replace in the future. Off-grid solar systems are a good alternative for some cabins and more remote places, but they still can’t compete with grid-tied systems regarding return on investment and ROI.

off grid inverter......no demand no output
grid tie inverter....generated as much power as available and assumes that the grid can use it all

Grid tie .............grid tie inverters must monitor the grid for 5 minutes and watch voltage and frequency. EDIT: and not output any power until the 5 minute clock is up. END EDIT. If there is one cycle where frequency or voltage is out of limits then the 5 minute clock restarts again. This is to prevent a grid collision where the grid has shut down and then comes back up again, sometimes the grid will come up for 8-15 seconds, determine that all is not well, shut down and then restart. It’s coded into the National energy policy set by the federal government the DOE.......U.S. Department of Energy.


Rule number 1 in doing this.....your loads must always be greater than the grid tie inverter can output. I have done this but it is not for newbie’s....you can do massive damage if you mess it up.


Some smart hybrid off grid inverters have a way of dealing with this for instance the MagnaSine MS4048PAE when paired with a grid tie inverter will “bump” its frequency up to 66 hz for a cycle or two when the output voltage goes out of range which will cause the grid tie inverter to shut down.

Not recommended unless you have a big system with MagnaSine, Schneider, or Outback or some such “hi-end” inverters