The Basics of a Solar Energy Storage System
Solar energy storage is a great solution to help balance out how solar contributes to your home’s electricity supply. Storage can be co-located with PV or standalone.
Storage is also helpful if your utility uses Time-of-Use rates and charges higher electric prices during peak demand hours. Energy storage helps to offset that increase and reduces tariff structure change risk.
Solar Panels
There are a few different ways to produce solar energy. Panels convert sunlight into electricity using one of three different types of silicon: monocrystalline, polycrystalline or amorphous. The type of silicon used determines the efficiency and cost of the panels. Most solar panel manufacturers use silicon because it’s an abundant and cost-effective material. Solar panels can be fixed or can track the sun’s movement throughout the day. Fixed mounting racks are less expensive to install and require less maintenance than tracking mounts.
Most solar systems will also include battery storage. This is because solar panels don’t generate energy when the sun is not shining. Pairing a solar system with a battery will allow your home to operate “off-grid” even though you will still be connected to the electric grid.
When your solar panels generate more electricity than you need, the excess will Solar energy storage system either flow into your battery or the grid. If you have a power outage, you will then draw on your energy reserves to keep the lights on.
Unlike gas-powered generators, solar batteries are quiet and environmentally friendly. They also have a much lower cost than traditional generators. There are two main kinds of solar battery technology: lead-acid and lithium-ion. The former uses the same chemistry as your car battery while the latter is found in most electronic devices including mobile phones and laptops. Both of these technologies have pros and cons but are great options for homeowners looking to cut their energy costs and dependence on the grid.
Charge Controller
A solar charge controller regulates the flow of energy from a PV array to a backup battery. Using solar panel voltage, the charger controls current into the battery based on charging “set points” which battery manufacturers establish for each stage of charge: bulk, absorption and float. The charge controller connects to the solar panels and disconnects them when the battery reaches a set voltage.
The most common type of solar charge controller is a PWM (pulse width modulated). It uses a series transistor switch that opens and closes at a high rate to control the current going into the batteries. It works well for 12V systems with only one or two solar panels.
Another option is to use a Maximum Power Point Tracking (MPPT) solar charge controller, which increases the efficiency of the system by pulling the panel voltage down to match the battery voltage. This reduces the current that is drawn from the batteries, which improves the battery lifespan and extends the time between charging cycles.
The MPPT also displays essential system information like the battery’s vitals, current voltage and state of charge on an LCD screen. This allows the installer to easily troubleshoot any issues. In addition, the installer can monitor energy production and consumption via a smartphone app to optimize performance and maximize savings.
Batteries
Solar batteries are a common way for homeowners to store solar energy. When electricity enters a battery, a chemical reaction stores the power until it’s needed later. When the battery is discharged, the reaction reverses and electric current exits the system. Lithium-ion batteries are the most popular choice for solar storage systems, but new technology is rapidly improving battery performance and affordability.
Solar storage can make your home more energy efficient by allowing you to take advantage of your rooftop solar’s electricity production at times when the grid is most expensive. This is especially beneficial if your utility uses Time-of-Use rates.
Storage can also help you avoid peak electricity usage, which is good for the environment and your wallet. When utilities must run their power plants during these peak hours, they burn fossil fuels to meet demand. A battery can allow you to save your excess solar electricity for nighttime use, avoiding the need to buy expensive electricity from the grid.
Solar storage can also make your home more resilient during power outages by providing backup power to critical loads such as appliances and lighting. Some solar installers offer critical load subpanels to help maximize the efficiency of your storage setup and prolong its lifespan during an outage.
Inverter
Once the energy has gone through the regulator and been stored in the batteries, there’s one more piece needed: the inverter. This is what will take the DC electricity from the battery and convert it into alternating currents (AC) that will be able to power your household appliances. In addition, this will allow you to use your solar power on cloudy days and even after the sun sets!
Without storage, the only way to make use of excess solar power is to send it to the grid. However, this can result in the system getting curtailed when there is too much generation and not enough demand, a problem that can be avoided with solar battery storage systems.
Solar battery systems can be co-located with or installed next to PV solar panels or they can be standalone systems. Regardless, they all perform Solar energy storage system the same functions: providing backup power, increasing energy independence and helping to reduce electric bills.
Batteries are the most common form of solar energy storage for residential applications. They are made up of lithium-ion cells that charge and discharge using a chemical reaction. However, thermal and mechanical storage options also exist. Both of these utilize a medium, such as molten salt or water, to absorb and retain heat from sunlight. This is then heated to produce electricity when the demand arises.
