Hybrid solar systems work similarly to grid-tied solar systems, but they use hybrid batteries and inverters to store energy. Most hybrid systems can also serve as backup power sources in a blackout as a result of storing energy, similar to a UPS system.
It used to refer to a combination of two different sources, such as wind and solar, but currently in the solar world the term ‘hybrid’ refers to a system that combines both solar and storage as well as being connected to the electricity grid.
What is a Battery Ready System?
Instead of a string solar inverter, battery ready systems use a hybrid inverter. Nowadays, hybrid inverters include a charger and connection for the battery, which will make it much easier to add a battery in the future. It is however more expensive to install hybrid inverters and if you don’t include batteries when installing the system, finding compatible batteries may become difficult.
Is a hybrid inverter necessary to add batteries?
No. Any existing grid-tied solar system can be upgraded to include a battery at any time using a ‘AC battery system’. More and more AC batteries, such as the Tesla Powerwall 2, are becoming available. Inverter and battery technology are developing rapidly, so investing in a battery-ready system may not always be a good idea if you intend to leave the battery in the system within 2 years. In light of the fact that battery technology is advancing rapidly, if you delay adding batteries, your system might become obsolete.
What is the purpose of storing solar energy in a battery?
The solar feed-in tariff (money or credit received for feeding solar energy to the grid) has been reduced by many governments and network operators. Therefore, traditional grid-feed solar systems lose their appeal because most people are not home during the day and therefore cannot use the solar energy as it is generated, so it is fed into the grid at no or very little profit.
During a blackout, a solar hybrid system will provide back-up power to store excess solar power. It is perfect for homeowners, but for most businesses that operate during daylight hours, a grid-fed solar system remains the most economical choice.
Self-consumption involves the ability to store your solar energy and use it when desired. The solar power system works exactly like a typical off-grid system, except that the battery capacity needed is far less than with a typical off-grid system, usually enough for peak consumption (8 hours or less) as opposed to 3-5 days.
Advantages of Hybrid Systems
- You can use solar power or cheaper electric power at off-peak times to store excess electricity.
- Utilizes stored solar energy during peak evening hours (known as self-use or load-shifting).
- Backup power is available in most hybrid inverters.
- Reduces grid energy consumption (reduces demand)
- Energy management (peak shaving) using advanced technology.
Disadvantages of Hybrid Systems
- The cost is higher mainly because of the price of batteries.
- Longer payback time – Greater return on investment
- Complex installations require more space and cost more to install.
- Typically, batteries last between 7 and 15 years.
Depending on the type of hybrid inverter and its capabilities, backup power may limit the number of appliances you can run at once.
Types of Hybrid Systems
There are four main types of hybrid systems:
- Basic hybrid inverters (no backup power)
- Multi-mode hybrid inverter (with backup power)
- All-in-one battery energy storage systems (BESS)
- Advanced AC-coupled systems (off-grid or hybrid)
Hybrid solar systems are the most energy-efficient when they use a simple hybrid inverter which consists of a solar inverter and battery inverter/charger together with smart controls which determine the most efficient use of your available energy.
The larger BESS systems consist of an inverter combined with lithium batteries in a package about the size of a refrigerator. Hybrid systems offer a wide range of features and capabilities that differentiate them from other appliances.
1. Basic hybrid inverter (no back-up)
The simplest hybrid solar inverter works similarly to a grid-fed system but also allows storage of solar energy in batteries for self-use. Inverters of this type do not contain a grid isolation device, which means they are unable to supply power during a blackout. The simple hybrid inverter would be the best economical choice if grid stability is not an issue.
2. Multi-mode hybrid inverter with back-up
Multi-mode inverters have backup power capabilities either built-in or as separate add-on units. When running normally, it supplies power to the house (designated power circuits), charges the batteries, and any surplus power can be fed back into the grid. The unit automatically switches over to the backup battery if there is a blackout or grid failure (in usually less than a minute).
3. All-in-one battery energy storage system
In recent years, hybrid inverters have been packaged with batteries in one complete unit. This is referred to as a BESS or Battery Energy Storage System. It can be retrofitted to a home that already has a solar system. These systems come in different sizes and are typically about the size of a medium refrigerator.
4. AC-coupled hybrid and Off-grid systems
In the past, most hybrid systems comprised two inverters that worked together to form an AC coupled system: Standard solar inverters and multi-mode interactive inverters. An interactive inverter is usually either a unit from the same brand, or it is compatible with the solar inverter to optimise battery charging.
A high level of power management is required for off-grid and hybrid systems with advanced AC coupled systems. Interactive inverters tend to be more expensive than all-in-one inverters due to the additional features and advanced software, but in many applications, they are more reliable, more efficient, and allow future expansion.