Battery Energy Storage Vs. Grid-Tied Solar Panel System

Grid-tied refers to a solar system with a connection to the utility grid. This system depends on an existing utility as a vital component. Therefore, as you utilize energy from the sun, you still have a connection to a local utility. It is the most popular choice for residential and commercial premises. It involves mounting of several solar panels on the roof and connecting it to the electrical system of the building. First, the power generated meets the immediate requirements of the home. After that, the surplus energy flows through your meter to the utility grid. The name grid-tie suggests that this system connects to the utility grid, which becomes part of the solar system. It differs from the stand-alone and off-grid systems. In the two, there is no connection to the utility power. The utility company keeps a record of the electricity that flows to the grid from your system.
  Grid-Tied System Battery Backup System
Cost Lower cost than battery backup system Quite expensive to buy solar energy storage batteries
Power control Dependent on the grid Independent from the grid
Components Grid-tie inverter power meter Solar energy storage battery,

Benefits of installing a grid-tied solar system

1. Saves on cost

When you use the grid-tied system, you save on your instant costs as the solar gets active and starts to generate power. It is the primary reason why most people prefers this system as it lowers their utility bills. When the system is functioning, the power you use is free. The system does not require a large energy storage system because of the grid-backup.

2. Cushion from the high utility prices

The system can last for around 30 years. In fact, there are grid-tied systems that are over 40 years old. For all that time, of course, the utility prices can’t be the same. Therefore, this system protects owners from the hikes and uncertainties of cost of electricity.

3. Increases the value of a property

solar system increases the value of a property. Potential buyers find it more appealing when a building has solar energy connection. It gives you an edge when the real estate market is tight, and you want to sell your property. For environmentalist buyers, this will be a deal sealer.

4. ITC Eligibility 

With this system, you are eligible for a 26% ITC in addition to exemption from sales tax. This does not only apply to the equipment, but also the installation cost.

Components of the grid-tied Solar system

There are two components used in a standard grid-tied solar system:
  • Grid-tie inverter
  • Power meter

a) Grid-Tie Inverter (GTI)

The primary function of this component is to regulate the voltage and current. Majority of electrical appliances use alternating current. However, the solar panels generate power in direct current. Therefore, conversion of the DC to AC has to take place. Besides, the inverters harmonize the frequency and phase of the current for it to flow to the utility grid. It also adjusts the output voltage to a slightly higher amount so that the extra power can flow to the grid.


Micro-inverters are found at the back of every solar panel in contrary to a single inverter for the entire array. Recently, there have been different opinions regarding which is the best between central inverters and micro-inverters. The latter is highly efficient but are expensive.

b) Power Meter

Most of the times, you need to change the current power meter for you to install a grid-tied system. You should use one that suits net metering. This meter can track the amount of power that flows in both directions.

What happens in case of power outage?

When you lose the connection to the utility due to an outage, the grid-tied system shuts down. This is a safety regulation that cushions solar panels from accidentally powering the grid which may result in damage. However, it is possible to have electricity even when there is a power outage. For that to happen, you need to incorporate a power storage battery into the system. When you integrate batteries to a grid-tied system, it becomes a grid-hybrid. You can as well incorporate a generator that will produce backup energy for essential items in the house. Battery storage in a grid-tied system can draw energy from the grid or the solar panel system. Therefore, you have a guarantee of backup power in case of an outage.

Battery Backup

A battery storage connection in a grid-tied usually consists of an automatic transfer switch. This allows a grid-interactive and an isolated mode. The system works like a conventional standby generator. When there is a power outage in the utility, connections in your house switch off. This means that you have no access to electricity. However, the battery storage system senses the outage and detaches your house from the utility. After that, the backup power system supplies energy to your house. Having battery storage for your grid-tied system is vital in maximization of solar production and storage of the extra power. When your system is producing excess power during the peak hours of the day, you can have the surplus energy stored in your batteries. When the cost of electricity is high in surging demand, you use your stored power. Therefore, you rely less on the grid during high demand evening hours. At such times the cost of energy is higher than normal. Therefore, you save a lot when you have your backup power.

Approaches to incorporate battery storage in a grid-tied system

If you wish to have battery storage in your grid-tied system, there are three approaches you can use.
  1. AC Coupling
  2. DC Coupling
  3. Use of a storage-ready inverter
  • AC Coupling

Grid-tied inverters require the grid power to function. They frequently detect grid voltage and frequency and switch off if it goes below the range. In a system with an AC coupling, the grid-tied inverter usually pairs to an off-grid one and a battery. The off-grid inverter acts as a second source of energy. It deceives the grid-tied inverter into remaining active. Through that, it is possible to charge the batteries and operate vital appliances when there is a blackout. Advantage of AC Coupling: AC coupling is the easiest and most convenient way, especially if it is a micro-inverter system. Disadvantage of AC Coupling: There is a challenge when it comes to sizing due to stringent requirements for inverter and size of the battery. In case the battery bank or inverter is undersize, the system might function poorly or entirely fail. Besides, an AC Coupled system might be expensive in case the present grid-tied inverter is big.
  • DC Coupling

In these systems, a charge controller connects the solar panel array to the battery. Basically, it is the mode of function for off-grid systems. It is possible to incorporate a grid-tied system where the central inverter is 600 volts. There is a manual switch to shift between off-grid and grid-tie modes. The drawback with DC coupling is that you cannot program it. To charge the battery, you have to turn the switch physically. Although the inverter on the battery switches on and power essential appliances automatically, the solar array can’t charge the batteries unless you manually turn the switch. Therefore, you should be around to turn on; otherwise, the batteries might drain such that you can’t recharge from the solar. Advantage of DC coupling: Unlike the AC coupling, this type functions with an extensive range of off-grid inverters and size of the battery bank. The disadvantage of DC coupling: The major downside of DC coupling is that you have to be around to start the charging. The system still provides back up power when you are not there, but there won’t be any recharge from the panels.

Replacing the grid-tie inverter

Replacement of the present inverter with a storage ready one is the most expensive option. However, it is the most flexible too. It is compatible with all grid-tie systems. Most of the times, homeowners wish to replace the current inverter with a type that can utilize a similar wiring array. Besides, they want one that is of the same size. Replacement of the inverter is a better option than the use of DC or DC. The design from the manufacturer considers energy storage and is thus best for the purpose. This tactic is not convenient when it comes to micro inverters. Removing the old ones and incorporating a new one in every panel is tough. Besides, the cost of labor is higher, and the process takes more time. Therefore, for the sake of micro-inverter systems, AC coupling is more convenient. Advantages of grid-tied inverter replacement: This approach is compatible with any system. Additionally, the storage ready inverters have several extra features. Disadvantages of grid-tied inverter replacement: The drawback is the high cost of labor, especially in a system that uses micro-inverters. It makes sense for an average household to maintain a connection to the utility grid. But having a battery backup is even more convenient. That is more so if the compensation policy by the utility company is not that good. Some utilities do not offer net metering at a retail rate; therefore, you won’t get the full credit amount for the power that you generate and send to the utility grid.