How Does Battery Backup for Solar Panels Work?

A typical solar energy system consists mainly of solar panels and an inverter, and when the sun is shining on your panels, electricity is produced. This electricity either goes to powering your home or business at the time of production. 

If you do not need the energy at that time, it feeds into the local power grid and you are generally credited by the utility company. When you need electricity at night or during other times when your panels aren’t producing, you must buy energy from the power grid.

However, a battery backup system allows you to store extra solar power onsite at your home or business for later use. This is helpful for managing time-of-use and demand costs as we’ll explore in the next section, as well as for short-term backup power if the grid experiences an outage.

Solar Battery Benefits

The most significant benefit of solar battery backup systems is that it can help you save money (and a lot of it!), especially if your utility company has time-of-use rates (TOU) or varying demand charges. Let’s look at what these terms mean.

Managing Tim of Use (TOU) Rates

TOU rates vary, as you might expect, based on the time of day that you are using electricity from the grid. Electricity will cost more per kWh at ‘peak hours’ than it does during other times of the day.

Managing Demand Hours

Demand charges essentially mean that you will pay more money the more electricity you use. The goal of this type of program is to motivate people to reduce their electricity usage, but sometimes energy consumption can’t be avoided. Demand charges may be assessed similar to TOU rates with higher charges if you use more energy at peak demand times, or they can be assessed based on the total amount of electricity you use in a month.

With a battery backup system, you can avoid higher fees from either demand charge assessment model by maximizing the amount of your own solar energy that you use, rather than selling it to the grid as it’s produced and then buying it back later at a potentially higher rate.

Electricity Critical Loads

Everything we do and own these days seems to require electricity. So what do you do when the flow of electricity stops for perhaps days or weeks? As we saw during Hurricane Sandy and more recently in Puerto Rico, having the energy to critically sustain ourselves and to avoid dangerous and lengthy power outages.

A solar storage system allows homeowners, businesses, and governments to keep critical applications powered while society itself has gone dark.

WHAT IS PEAK HOURSPeak Hours Usually include the late afternoon and evening, when people generally use the most electricity to turn on lights, power TVs and kitchen appliances, and so forth. It’s also the time when solar panels are not producing a lot of power, so the utility companies know that you will have no other option but to pay the higher rates.

Free Consultation with Local Asheville Solar Installer

Ready to get started with a solar energy storage system? Contact our team of experts at Pisgah Solar today for a free consultation and price quote.

Solar Battery Backup Costs

The cost of solar battery backup systems ranges dramatically based on the battery that you choose and how much capacity you need to match your solar energy system. In general, the price can start from $500 and can increase in cost depending on the brand, additional accessories, and product availability.

The exact installation costs vary based on the difficulty of the project and the ease of access to existing components of the system. Contact us at Pisgah Solar today for a free quote of how much it will cost to install a battery backup system at your home or business.

Can I Add a Battery to My Existing Solar Panel System?

Generally, it’s possible to add a battery backup system to almost any existing solar panel system. The difficulty level will depend on whether or not your system was designed with the intention of eventually adding a battery system. If it was, the process is relatively simple and won’t require much equipment other than the battery itself. However, if your system wasn’t designed with battery backup in mind, you will either need to replace your inverter or choose an AC coupled solution.

Best Solar Battery Backup Systems

The Generac PWRCell and Tesla Powerwall are two of the most popular and highest quality battery backup systems. They are both lithium batteries and both can be scaled up by combining multiple units to create a larger battery with more capacity to meet the needs of your solar energy system.

Tesla Powerwall System

To install a single Powerwall unit, the cost ranges from $14,500-$16,000, or you can install two units for around $26,000. Each unit has a maximum power rating of 5 kW and a usable capacity of 13.5 kWh.

Generac PWRCell

Generac PWRCell System

The Generac PWRCell starts around $10,000 for the smallest unit, but of course the larger units will cost more. It offers a maximum continuous power rating of 3.4 to 6.7 kW and a usable capacity of 8.6 to 17.1 kWh depending on the size of the model you select.