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The word ‘hybrid’ in the field of green energy has been used to refer to two sources such as solar and wind. However, in the solar world, ‘hybrid’ refers to a solar power system that has both energy storage and connection to the electricity grid.
The hybrid solar system is one of the three types of solar power systems (off grid, on grid, hybrid) that exist in the market today. It is the most complex among the three as it involves more electrical components for the system to function at its fullest potential.
Despite the many touted benefits of the hybrid solar system for homes, it is not as widely adopted as it should be, due to reasons which will be made clear in this article. A lack of proper understanding also contributes to the lack of adoption. This article will attempt to resolve that.
Hybrid solar system design
A hybrid solar system is designed to complement a grid-tie or on grid solar system (in some countries referred to as regular battery-free system). Typically, it would have photovoltaic panels, a hybrid solar inverter, solar batteries and battery inverter linked to the meter or switchboard of a property that is connected to a power grid.
For the system to work, the hybrid solar inverters and solar batteries must be compatible with each other. The batteries enable the hybrid system to store solar-generated power.
From this store of power, a hybrid solar system can offer a backup power supply during a blackout or during periods with lack of sunlight. With the right hy-tech components, there can be Uninterrupted Power Supply (UPS).
This system can also pull electricity from the grid in high energy use periods like cold winter months. AC electricity can also be converted to DC to be stored in the solar batteries.
What are the hy-tech components used in a hybrid solar system?
First, we have the hybrid solar inverter and battery inverter. These enable the switching of DC to AC and vice versa, which regular solar components cannot do.
In order for a hybrid solar system to be controlled, a compatible software is required between the hybrid inverter and battery technologies.
Then there is the Emergency Power Supply device or EPS. It enables the system to automatically switch from solar batteries to power in the event of a blackout.
How does a hybrid solar system work?
Just like any solar panel system, it draws solar energy from sunlight during the day. Any unused DC electricity produced can be channelled into the solar batteries in the system. At night, or when the skies are gloomy, you can draw power from the batteries or from the grid.
When the batteries are fully charged, excess power is exported into the power grid at the Feed in Tariff (FiT) rate. Conversely, when the batteries are drained out, a hybrid system allows you to charge them using power from the grid.
Generally, a hybrid system is configured for solar usage first, then battery power, and lastly grid power. This is meant to help one save on the electricity bill.
That being said, it is possible to instruct a hybrid system to do precisely what you want, as it is fully programmable.
For instance, if there isn’t enough solar-generated power to fulfil daytime usage and charge the solar batteries at the same time, you can program the system to charge the batteries from the grid during off-peak electricity rate.
In some countries, utility companies may charge a higher rate when electricity usage goes above a certain level. They call this peak-rate charge. To circumvent this, you can program your hybrid solar system to draw power from batteries instead of the grid.
Choosing the right type of hybrid inverter
Solar inverters that can be hooked up to both solar and batteries are generally called hybrid inverters or battery-ready inverters. In some markets, not all hybrid inverters are created with equal ability.
You need to know the subtle differences in order to get the right one that can give you automatic uninterrupted power supply (UPS).
1. Grid connected inverter
This type offers no blackout protection. If there is a power outage, it does not draw power from the batteries on its own. In this instance, an EPS will be required along with other components to make UPS possible.
2. Multiple mode inverter
‘Multi mode’ means it can operate in more than one mode, i.e. connected to the grid and stand alone. This type offers blackout protection but there is a delay before power backup kicks in. It can be used to connect power to the whole house or just a specific circuit.
3. UPS multiple mode inverter
As its name suggests, it is designed to provide uninterrupted power supply. In the event of a blackout, it will draw power from the battery system immediately. On top of that, it can function with the grid and in off-grid mode.
Hybrid solar system price
For a solar installation on a house, a hybrid system is generally cheaper than an off grid solar system. Compared with a grid-tie, hybrid is definitely more expensive; in fact, the price can be at least double.
If you line all the 3 types of solar power systems up, you’ll have on-grid as the cheapest followed by hybrid then off grid as the most expensive.
What adds to a hybrid solar system cost is its additional components compared with an on grid type. Hybrid solar inverters are also pricier than those of on-grid installations.
That is because an on-grid solar inverter is based on simple technology. It is only required to convert DC to AC electricity as DC passes through it.
A hybrid solar inverter, on the other hand, is the most complex type of inverter in the solar world, even more complex than an off-grid inverter. It has technological components which allow it to function in both on-grid and off-grid modes. This is what makes it the most expensive.
The overall cost of a hybrid system is also dependent on how many batteries you want and how much power you need for the house. The more power and storage capacity, the higher the bill.
Lastly, there is the cost of additional components which enable it to automatically run in off-grid mode – the EPS as well as additional control and switching equipment. These can pile on at least $1,000 more.
How much more do hybrid inverters cost?
A hybrid solar inverter can cost about $1,000 to $2,000 more than a standard solar inverter, depending on the brand and inverter size.
How to make the best use of a hybrid solar system
If your country has no FiT policy or has a lousy one, depend on solar energy for the bulk of your usage. In other words, max it out.
If your country has net metering for solar or different electricity rates, use as much solar power as you can during peak hour rates. Then, export excess solar power when the FiT rates are high.
Advantages of a hybrid solar system
- Flexibility of storing power generated during the day instead of feeding it back into the grid
- Fully programmable to provide a smart combination of all the energy sources – grid, solar and battery
- Reduces power consumption from the grid
- Optimal usage of solar power at peak usage times
- Can provide uninterruptible power
- Overcome solar export limits imposed by local electricity provider
Disadvantages of a hybrid solar system
- Overall installation cost is far higher than a grid-tie solar system
- Battery life of 7 to 15 years make the return of investment low
- Limitation in the number of appliances it can support, depending on the hybrid inverter and its capacity
Some frequently asked questions
Can a grid-connected house run on solar power alone?
Yes, only if you have very low electricity demand. Otherwise, you will need a huge battery backup with a very large solar system. This may end up costing you more than just using power from the grid.
Do you need a hybrid inverter to add batteries?
No. A battery can be added to any existing grid-tie solar system at any time.
Can I add batteries if I already have a regular solar power system?
Yes. The easiest way to do this is ‘AC coupling’. This means you don’t alter the existing solar wiring. You simply connect the solar battery to the AC circuit of the house.
Difference between the hybrid system and ‘battery-ready’ solar system
‘Battery-ready’ has been used in sales-speak to describe a system suitable for adding solar batteries later. It is not identical in meaning to ‘hybrid’.
In summary, a hybrid solar system is a grid-connected solar power system with added batteries, hybrid inverter and other hy-tech components, which enable the system to offer UPS.
For a house installation, it is cheaper as a stand alone solar system, but costs over double that of a regular battery-free system. The trump card of a hybrid solar system is its ability to store and draw power from both solar energy and the grid.
Because of that, it does not need a generator, which in the long-term, could cost more. This is especially so for houses located in areas where there is regular power outage, extended periods of high power usage (such as during hot summer months and freezing winter months) or expensive grid power rates.