A solar power system is more than just a few fancy panels attached to your roof or set up in a sunny position on your property. One of the most important components to your solar power system is the inverter.
A solar inverter, or sometimes solar converter or a PV inverter, converts the variable DC output of a PV (photovoltaic) solar panel into an AC current that can be used by a commercial power grid or by can be fed back into your own off grid network.
How do Inverters work?
In simple English a solar inverter works in this way:
- The sun shines down onto your solar panels. Your solar panels are cells that are made of semiconductor layers of crystalline silicon or gallium arsenide. These layers are a combination of both positive and negative layers, and they are connected through a junction.
- The semiconductor material absorbs the sunlight and transfers the light’s energy to the PV cell. This energy knocks electrons loose, and they move from one layer to the other, thereby producing an electrical current. This is a direct current (DC).
- This energy is then stored in a battery bank for later use or sent directly to an inverter, depending on your set up and type of system.
In order to use this generated energy within a residential setting, the energy needs to be converted from DC power to AC power as all home appliances require an AC power supply. This is where you need an inverter.
The inverter takes the DC energy and runs it through a transformer. The inverter runs the DC energy through two or more transistors that are rapidly turned on and off and feed two different sides of the transformer. This in turn creates AC power which you can then use, store or send back to the power grid.
Types of Inverters
There are generally three broad types of solar inverters available for your system:
- Stand Alone Inverters
- Grid Tie Inverters; and / or
- Battery Backup Inverters
Each type of inverter has a specialised function and it is important to have the right type of inverter for your system to get maximum benefit from your investment.
Stand Alone Inverters: These are used in systems where the inverter needs to draw DC energy from batteries that get charged by the photovoltaic arrays (solar panels). Quite often, stand-alone inverters will also incorporate integral battery charges which can refill the battery from an AC source.
Grid Tie Inverters: These are designed to shut down automatically upon any loss of power from your power company supply. This is for safety reasons. If you have a Grid Tie Inverter you will have no backup power if there is a power cut from your power supplier (ie Vector, Meridian, Genesis, etc)
Battery Backup Inverters: These inverters are designed to draw energy from a battery. They manage the battery charge via an on board charger, and then send any excess energy back to the power grid.
What are the Advantages and Disadvantages of having a Solar Inverter?
Without an inverter it is impossible to create the right type of energy to be used in your home with your appliances so the biggest advantage to having an inverter is being able to run your home as if you were still connected to the national grid.
We categorised inverters (above) into three generic types – however within these types you can also choose centralized string inverters, micro inverters or power optimisers. What are these? Centralized string inverters are the most common technology option for rooftop solar panel systems however micro and power optimizers have gained popularity in recent years.
Advantages of Centralised, Micro and Power Optimiser Inverters:
- If you are looking for the most affordable option – you need a centralised string inverter. They function best if you have your solar panels installed on your roof.
- If your solar panels are installed on a shaded part of your roof, or you have many angles to your roof and the panels are spread out across the angles then a micro inverter or power optimizer will give you the best results.
- Micro Inverters and power optimizers are more efficient than a centralised string inverter and if you have either of these types installed then you will receive slightly higher amounts of energy from your system than if you have a centralised string inverter.
- If one of your solar panels in your system is underperforming, a Micro Inverter or a Power Optimiser device will ensure that your system still produces a substantial amount of power. If one panel fails, the others will still continue to produce electricity IF you have a Micro Inverter or Power Optimiser Inverter installed.
- Because Micro Inverters and Power Optimisers are both relatively new technology, they also have the ability to allow you to monitor the performance of individual solar panels, through your smartphone or via a web portal.
- They typically come with longer warranties than string inverters – up to 25 years when they are integrated with solar panels. String inverters are usually warrantied for 10 years and will typically remain operational for about 15 years before needing to be replaced.
Disadvantages of Centralised, Micro and Power Optimiser Inverters:
The potential disadvantages of micro-inverters and power optimizers have to do with maintenance and reliability, rather than how well the devices convert DC electricity to AC.
- With a central string inverter, you can experience a substantial drop in overall system power generation if a single panel stops producing power.
- Both Micro Inverters and Power Optimisers have higher costswhen compared to centralised string inverters, because they require more pieces of equipment.
- With micro-inverter and power optimizer systems, all or most of the critical equipment sits on the roof through rain, snow and heat. By comparison, string inverters are generally located off the roof.