Hybrid solar systems generate power in the same way as a common grid-tie solar system but use batteries to store energy for later use. This ability to store energy enables most hybrid systems to also operate as a backup power supply during a blackout. For those new to solar read our how solar works article.
Why store the solar energy you generate rather than feed it to the grid? Many governments and electricity network operators have reduced the solar feed-in tariff or FiT (money or credit received for feeding solar energy to the grid), which means grid-feed solar systems have become less economical. Since most people are working during the day and are not home to use the solar energy as it is generated, the energy is fed into the grid for very little return. However for the majority of commercial businesses which operate during the day a common grid-feed solar system is still the most economical choice.
Hybrid solar systems enable you to store solar energy and use it when you're home during the evening when the cost of electricity is typically at the peak rate.
The ability to store and use your solar energy when desired is referred to as self-use or self-consumption. It works in the same way as an off-grid power system but the battery capacity required is far less, usually just enough to cover peak consumption (8 hours or less) as opposed to 3-5 days with a typical off-grid system.
Solar Hybrid System Advantages
- Stores & saves solar or cheaper off-peak energy.
- Allows use of solar energy during peak times (self-use or load-shifting)
- Power available during a grid outage or blackout –UPS
- Enables advanced energy management (ie. peak shaving)
- Enables energy independence
- Reduces power consumption from the grid (reduced demand)
Solar Hybrid System Disadvantages
- Higher cost than grid-feed solar. Mainly due to the high cost of batteries.
- Larger more complex installation requires more room and higher install cost.
- Battery life of 7-15 years.
- May limit how many appliances you can run at the same time (depending on the type of hybrid inverter and its capability)
HYBRID SYSTEM TYPES - Technical Guide
The following is a detailed technical guide of the various hybrid solar systems and inverters on the market. The systems available may vary depending on the local distributors and electricity network operators in your country. Refer to our complete hybrid and battery storage review for a comparison of the various hybrid inverters and battery storage systems.
This section is divided into two parts:
1. Basic all-in-one hybrid inverters and complete systems
2. Advanced grid interactive systems (off-grid or hybrid)
1. All-in-one hybrid inverter/system:
The most economical hybrid solar Inverter is the all-in-one inverter which contains a solar inverter and battery inverter/charger together with clever controls which can be programmed to determine the most efficient use of your available energy. An all-in-one hybrid system is basically a hybrid inverter together with an integrated lithium battery in one complete package usually about the same size of a fridge. However like most appliances there are several features and capabilities which differentiate the wide variety of systems available.
1.1 All-in-one inverter (no back-up)
This is the most basic kind of hybrid solar inverter and works much like a grid feed solar inverter but also enables storage of solar energy in battery system for self-use. The main disadvantage of this type of Inverter is that is does not contain a grid isolation device which means it cannot supply power when there is a blackout (commonly known as an uninterruptible power supply or UPS function). Although if grid stability is not an issue then this simple hybrid inverter would be an good economical choice.
AVAILABLE INVERTERS: Solax X-hybrid, Growatt, SolarEdge, Sungrow, (Samsung hybrid system including batteries)
1.2 All-in-one inverter with back-up (UPS)
This more advanced all-in-one hybrid inverter can often be used as both an on-grid or off-grid inverter as it has back-up capability built-in. Under normal operation it can supply power to the home (designated power circuits), charge the batteries and excess power can be fed into the grid. If there is a blackout or the grid becomes unstable the unit will automatically switch over to battery supply and continue to operate independently from the electricity grid (in usually less than half a second).
1.3 All-in-one system with integrated battery
A more recent trend is to package the all-in-one hybrid inverter together with a battery system in one complete unit. This offers a very neat and cost effect option which is usually about the size of a medium fridge. These systems are very easy to install but can have some limitations as some models cannot be expanded at a later date.
2. Grid interactive hybrid/Off-grid systems
Until recently (before cheaper all-in-one hybrid inverters) most hybrid systems consisted of two different inverters which worked together to form what is known as an AC coupled system; a standard solar inverter and a sophisticated interactive or multi-mode battery inverter.
The Solar inverter can be any standard unit but it is usually either the same brand or is compatible with the interactive inverter to optimise battery charging.
The interactive or multi-mode inverter acts as a battery inverter/charger and complete energy management system using clever, programmable software to optimise energy. Interactive inverters supply power in the same way as an off-grid inverter but also control grid connection (import and export power) and can be setup to automatically start and run a back-up gen-set (generator).
Key features of a grid interactive system
- Powerful battery inverter to supply continuous high loads
- Advanced multi-stage charger for lead-acid or lithium batteries
- Automatic AC transfer switch (UPS function) built-in
- High pass through power capability
- High surge load capability
- Generator control – Auto start / stop
- Can also be used for high end Off-grid power systems
- Remote monitoring
- Grid feed-in and limiting when excess power is generated
- Peak shaving to reduce peak demand
- Load shifting and advanced energy demand management
Advanced interactive systems are used for off-grid and hybrid installations which require a high level of power management. The powerful software used to run Interactive inverters enable energy controls such as peak shaving, plus data logging and PLC capabilities through digital input/outputs and relay controls. These systems can also work with very large battery banks and incorporate specialised battery monitoring and temperature sensors to prolong battery life.
Due to the many features and advanced software the cost of interactive inverters is typically higher than all-in-one inverters but in many applications the extra cost is worth the additional investment as they are generally more reliable, more efficient and enable future expansion.
AVAILABLE INVERTERS: Selectronic SP PRO, SMA Sunny Island, Victron Energy Multiplus, Schneider Conext XW, Outback Radian Series (US).
Please refer to our hybrid inverter and system review for the full list of hybrid systems and inverters currently available.