With the growing popularity of solar energy storage systems, many homeowners are looking to add batteries to their existing solar panel systems. Solar batteries are particularly attractive in areas with an unstable electrical grid, such as areas regularly hit by severe weather. Due to the structure of utility rates in some areas, some homeowners are able to lower their electricity bills more with batteries. Let’s review this topic so you can better serve your existing customers.
Can I add a battery to an existing solar system?
Yes, it is possible to retrofit an existing system with a solar battery. This is an excellent way to reduce the impact of power outages by making solar power available 24/7.
Solar panels are almost always compatible with energy storage systems. However, if your solar system was not originally designed with battery power in mind, you will need to replace your existing solar inverter or install an AC-coupled battery.
Why add batteries to a solar system?
Adding batteries to a solar system provides energy storage, allowing users to store excess solar energy for later use or power outages. Batteries for solar panels cope with fluctuations in energy production and consumption, providing a reliable power source during periods without sunlight or power outages. The main motivation for adding solar batteries is to increase self-sufficiency and reduce dependence on the power grid for both residential and commercial applications.
Considerations for adding solar.
Before you plan your approach to upgrading the batteries in your solar system, there are several factors to consider.
What type of solar inverter is the system currently using?
Unless your solar system is designed to store energy in batteries, you will need to either replace the inverter or install an AC-coupled solar battery, such as a Tesla Powerwall or Panasonic Evervolt. These types of batteries have a built-in storage inverter, so they can work with both microinverters and standard string inverters.
However, some homeowners knew they would want to add a battery in the future and installed a storage-ready solar system with a hybrid inverter such as the Solaredge Storedge. In such cases, they may pair a DC-coupled battery with their system, but such a situation is rare.
It is also worth considering the expected remaining life of the existing inverter. For example, many string inverters have a life expectancy of 10 to 15 years. So if the equipment is already 10 years old, it may be better to replace the inverter with a hybrid inverter and switch to a DC-coupled solution.
Is the solar system AC or DC coupled?
An AC-coupled system with batteries has two separate inverters. One of them converts direct current (DC) from the solar panels into alternating current (AC). This energy can power the house, and the excess can go to the electric grid. The other inverter works with a battery that stores DC energy.
The DC-coupled system, on the other hand, has a hybrid inverter that can reverse the current from both the solar panels and the battery. This option allows direct charging of the battery with DC power from the solar panels. When supplying power from the battery to your home or the grid, it can also convert DC to AC.
If you install an AC-coupled battery and keep the existing inverter, the initial cost is likely to be lower, but the system may be slightly less efficient. In the long run, this can add up. If your customer wants to reduce their costs, this is probably a better option, as they will not have to incur the additional cost of replacing the inverter.
However, a DC-coupled solar system is a good choice if your customer cares more about system performance. With a DC-coupled system, the solar panels can charge the batteries directly without converting the energy, which reduces inefficiency.
Are there any permits for solar installation or legal requirements from AHJ authorities to add a solar battery to an existing system?
Local authorities with jurisdiction (AHJs) will likely have permit requirements for installing a battery energy storage system. In addition, you may need to update your interconnection agreement with the local utility. Therefore, please contact the AHJ to find out about their requirements and specifications before starting your project.
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Solar panel battery capacity needs.
Correctly sizing the battery capacity is critical, so start by considering how the customer wants to use the stored energy. For example, some homeowners only want emergency power during an emergency, while others want whole-house backup power.
Unfortunately, whole-house backup power can be very expensive, especially if they have large loads such as air conditioners, electric heating or hot tubs. For this reason, most off-grid systems usually don’t have many large electrical loads, or homeowners use them very sparingly.
To size a battery storage system, determine the home loads and how often they are run. Most smaller battery systems can handle relatively small loads, such as a refrigerator, stove electrical components, some lights, a Wi-Fi router and a few electronic devices, but will quickly be depleted by power-hungry appliances.
Customer expectations for adding a solar battery.
It is very important to assess customers’ expectations of how much electricity the batteries can provide during an outage. It may not be possible to run electric water heaters, electric clothes dryers, heat pumps, air conditioners, power tools or electric stoves without multiple batteries. Solar installers typically add a critical load panel to prioritize the most important loads.
Financial savings from adding solar batteries.
If your customer lives in an area with time-of-use (TOU) rates and net metering, they can save even more by installing a battery and drawing power from it when rates are highest. In areas with TOU rates, the cost of energy tends to be higher in the late afternoon and early evening, and lowest in the middle of the night. Similarly, electricity can cost more per kWh in summer than in winter.
In addition to time-of-use rates, some residential customers may also receive demand charges. With both on-demand chargers and time-of-use rates, having solar batteries will help your customers lower their electricity bills by using stored energy when it is most expensive.
How do I add a battery to a solar panel?
Adding a solar battery to an existing photovoltaic system involves several steps:
Assessing solar storage needs. Determine the customer’s energy storage needs. Please consider factors such as daily energy consumption, desired backup time during power outages, and energy independence goals.
Please comply with the regulations regarding permits for solar installations. Please install a solar panel battery system.
Upgrade or add a solar inverter.
Reconfigure the solar wiring.
Programming and configuration: please program the system to work in conjunction with the solar panels. Configure battery charging and discharging settings based on your preferences and energy needs. If the power company applies time-of-use rates, please take this into account.
Test and monitor the photovoltaic system.
Can I use solar panels without a solar battery?
Yes, you can use solar panels without an energy storage battery. In a grid-connected solar power system without energy storage, solar panels produce electricity when the sun shines, and this energy is immediately consumed at home or transferred back to the power grid. When the solar panels produce more electricity than the home consumes, the excess can be sent back to the grid, often earning solar credits or compensation under net-metering programs. This setup does not require a battery for energy storage.
However, a solar system with a solar battery allows homes to store excess energy generated during the day for use at night or on cloudy days. Adding a battery to a solar system provides backup power and increases the ability to use solar energy when the sun is not available.
Adding batteries to a solar system may be the right solution for your customers.
Severe weather conditions are becoming more common, causing more frequent power outages. Due to falling solar battery prices and more incentives for energy storage, many homeowners with solar systems want to add backup energy storage. While this is certainly possible, proper planning and knowledge are key.