What are Solar Energy Inverters?

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What is a Solar Inverter? The first inverters were mechanical and invented in the 19th century. A spinning motor was used to constantly change whether the DC source was connected back or forth. Today is a little bit different with electrical switches being made out of transistors, no moving parts with solid-state devices. Transistors are made of semiconductor materials like gallium arsenide or silicon, Allowing the control of the flow of electricity in response to outside electrical signals.

If you think of the solar panels as the muscle of your solar energy system, then the inverter would be the brain. The solar inverter is essentially a computer that is installed with the other components of your solar energy system that “inverts” your energy to alternating current (AC) from direct current (DC). Which the electrical grid uses.

In AC, the electrical current will flow in both directions in the circuit as the voltage changes from positive to negative. In DC, electricity is maintained at a constant voltage in one direction. Inverters are just one example of devices called power electronics that administer the flow of electrical energy.

As many of the leading manufacturers are releasing their advanced newer models with brilliant smart home energy management features and online monitoring. The title for best grid-tie solar inverter has never been closer. The hype around hybrid systems and home battery systems is growing. However, it’s early days at the moment for batteries and the majority of solar installations will still need a dedicated solar inverter.

With having a solar system for your home, your inverter will more than likely perform multiple functions. As well as converting your solar energy into AC power, it monitors the system and provides a communication portal with computer networks. Solar-plus–battery storage systems depend on the state of the art inverters to operate on their own externally without support from the grid during times of outages if they are designed to do so.

Solar Inverter Types


Micro Inverters


Micro inverters (micros) are very small solar inverters and are directly attached to individual solar panels. Since each micro inverter and panel operate independently, they tend to be a good choice for complex roof layouts and locations with shading issues. They tend to be a little higher in cost but micros are very popular in North America due to the many advantages they offer over string inverters.

Off-grid Inverters


Off-grid or stand-alone power systems need powerful battery inverters with inbuilt chargers which can be set up as either direct current (DC) or alternating current (AC) coupled systems. Up to date off-grid chargers/inverter can be used to create advanced hybrid grid-connected systems, also known as multi-mode inverters.

String Solar Inverters


String solar inverters are used as a string of solar panels linked together in series. String inverters would be more commonly used across Europe, Australia, & Asia, but are beginning to become more popular in the US.

What does a solar inverter do? What does a DC to AC inverter do?

So let's go over it again in a little bit more detail. There are a few different ways it can be viewed. So if you view DC and AC as two different languages, think of your solar inverter as the translator.

With all the electrical wiring running through your home carrying or “speaking” AC as do your utility grid and appliances. But you're your solar panels “speaking” DC. So, there’s a translation barrier. Your solar energy system can’t send power to either your utility grid or your home without assistance. An inverter provides that assistance.

Picture yourself as a direct current (DC) battery doing your thing and someone taps you and wants you to produce an alternating current (AC) instead. What would you do? If all the current you are producing flows in the same direction, how about adding a switch to your output lead? Switching your current on and off, extremely rapidly, would provide pulses of direct current (DC), which would do at least half the job. With making a proper alternating current (AC), you'd need a switch that allows you to reverse the current completely continuously about 50‐60 times per second. That is over 3000 times a minute.

If you think of an electric doorbell, the switching device works a bit like this. When the power is connected, it will magnetize said switch, pulling it open and switching it off briefly. A spring will pull the switch back into position, turning it on again and continuously repeating the process.

So as you now know the main purpose of the solar inverter is to translate or “invert” the solar energy that is being generated by your solar panels, from Direct current (DC) to alternating current (AC) so that your and utility grid and home can use it. This is the first and most important service it will provide. Additional to inverting energy from Direct current (DC) to alternating current (AC), your inverter has another very important purpose. It also provides online communication.

Solar inverters allow you to connect your solar energy system to the internet, which in turn allows you to access information about your system. This is especially helpful when you want to compare your solar energy production against your household energy consumption (the energy reflected on your utility bill) or to ensure that your system is functioning properly. There is a Solar app for Apple or Android and you can see at any time the amount of solar energy your system is producing.

How long do solar inverters last? What is the lifespan of a solar inverter?


To be honest no one really knows precisely how long a solar inverter can last but it is estimated around 10 -15 years.

The inverter is a core component of a solar PV system and has been tasked with the conversion of direct current (DC) energy from solar panels into alternating current (AC) energy that runs our appliances and homes.

Many factors such as regular maintenance, humidity, and heat can have a direct effect on the overall lifespan of your inverter, not forgetting the performance of the solar system as well. Also not to forget the grade of electrical components it's made of and the manufacturer.

Imagine your solar inverter as a car and ask yourself how long will a car last and just about anyone will tell you it depends on the make of the car and how well previous owners have looked after the vehicle.

You can apply this exact same theory to solar inverters but there are some ways to gauge what you can expect from each style of an inverter and how long it may last. One of the best ways to go about this is to find out how long the inverters warranty is guaranteed for, this will more than likely vary depending on the manufacturer.

Inverters have a life-span estimated to be around 10 - 15 years as a result of them having more electrical components that are sensitive to heat. In some cases, a high-quality inverter that is well-maintained could last up to 20 years with just a slight drop in inefficiency. Unlike solar panels who have a life-span of 25 years due to no moving components.

However, battery-based inverters having to run 24/7 due to their battery storage capabilities that cause the equipment to overload more frequently, can see shorter lifespans. When it comes to Microinverters and DC Optimizers, the majority suspects at least 20 to 25 years but no one knows for sure as they haven’t been around the solar industry long enough.

Excessive heat can and will eventually cause premature deterioration to your PV inverter and even lead to system performance issues, this one thing we know for sure. Whoever is taking care of the installation of the PV system is following the correct guidelines when choosing the location for the inverter.

Why do we need an inverter for solar panels? Do I need a solar panel inverter?


When you think about solar energy, the first thing that comes to mind is the large flat panels fitted to the rooftops. Now, this is not the only thing needed for converting the sun’s energy into energy for the building. For the sun's energy to be used by the numerous appliances throughout your home, it needs to go through an important component of the system – the solar panel inverter.

An inverter is an absolute MUST, as it is responsible for converting the power collected by the panels into a current that allows you to use it in your home. So understanding the importance of a solar inverter, you must, first of all, understand the whole solar process and answer the question below.

How does the solar inverter work? How do solar inverters work?

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In general solar panels will possess a non-conductive layer in between two main silicon semiconductor layers that are wired together. The electrons on the upper silicon layer will activate when exposed to photons that are produced by the sunlight. When these electrons are activated they become attracted to the atoms in the bottom semiconductor layer and travel through the wire to get to the bottom layer in one direction creating an electrical charge or current flow which is also known as DC or direct current.

In order for the solar energy to be back-fed into a utility grid safely or be utilized throughout a home, it must be converted to AC or alternating current. That’s where the need for a solar inverter comes into action as they handle this task efficiently along with assuring the system stays at an optimal level for peak performance.

Collection of the sun's energy


The process begins with the Solar-powered photovoltaic (PV) panels converting the sun's rays into electricity by exciting electrons in silicon cells using the photons of light from the sun. Throughout the daylight hours, the panels collect the power, and continuously produce the direct current (DC) to be sent elsewhere for conversion. The individual panels combine the collected power and sending it to the inverter which is the most essential part of the whole process. This electricity will then be used to supply renewable energy to your business or home.

Inverting


In the form of a small box, most inverters will keep a record of how efficiently the panels are working, giving you a specific gauge on how much power the system is collecting. A central inverter will more than often be out of the way on the side of a home or business, receiving the direct current (DC) from the solar panels. The vast majority of home appliances such as TVs, fridges, and lights, etc are running off of alternating current (AC). So, the solar power inverter’s role is to convert the direct current (DC) into the required AC for your everyday use at your business or home.

Micro-inverters are used in some systems rather than using a single central inverter. These are attached to the underbelly of each panel, they collect, transform DC, and convert this power to an alternating current. This option does tend to be on the more expensive side.

Function


Once the inverter has created the correct power input, it will be sent to the fusebox to be delivered throughout the building efficiently. When the switchboard receives the AC, it is delivered to the home to power all of the required appliances. From the fusebox, excess power is either sent back into the grid or a battery storage system. This will vary depending on your system set-up and usage.

The inverter is extremely important for the conversion of the energy collected from the panels to a power source that can be used in your home. Think of the solar inverter system as a middleman, and without it, the power collected by the panels would be absolutely worthless.

If you are looking for more information about solar inverter options, give us a call and speak to one of the knowledgeable professionals about the best products available.

What size solar inverter do I need? How big will my inverter need to be?


The size of your inverter should be similar to the direct current (DC) rating of your solar panel system. If you're installing a 6 kilowatt (kW) system, then you should expect the recommended inverter to be around 6000 W, give or take a small percentage.

Solar inverters are one of the most necessary parts of a solar panel system. Their job is converting direct current (DC) electricity from your panels to alternating current (AC) electricity, which in turn will power your appliances. When it comes to designing your solar panel system, the size of your inverter will always play an important role in your overall electricity production.

How to determine inverter size? How do I know what size inverter I need?


An inverter supplies two needs – surge or peak power, and the typical or usual power. Solar inverters come in a variety of sizes, big and small. Similar to solar panels, the size of an inverter can be rated in watts (W).

Volts (120) x Amps = Watts

So if your fridge for example was to 100 watts and your DVD player another 100 watts, a 300-watt inverter would be the recommendation. If it is a motor-driven appliance, it would need an additional start-up (surge) wattage (around 2-3 times the uninterrupted wattage is required) to get the appliance started.

Surge


The surge would be the maximum power that the inverter will supply, in most cases no longer than a second unless this is specified in the inverter’s details. Specific electric motor appliances require a  higher start upsurge than they do when once running. Pumps, freezers, air conditioners, and compressors are the most common examples. You will want an inverter with a continuous rating that can handle the surge rating of your appliance so you won’t burn out the inverter prematurely. Don’t rely on the inverter’s surge to start your appliances because inverters don’t like to operate in their surge mode unless the manufacturer claims to have a longer surge time than normal.

Typical


Typical is what the inverter supplies on a regular basis. This is the continuous rating. This is usually much lower than the surge. This would be what it takes to run the microwave or the first few seconds it takes for the motor to start up for the refrigerator or what all loads combined will total up to.

Installers will take three primary factors into account when it comes to solar inverter sizing, your location, the size of your solar array, and site-specific conditions.

How to size your solar array? What size solar array do I need?

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Photovoltaic (PV) solar panels come in a variety of different wattage sizes and voltages. They are designed to supply your home with energy. Solar panels are classified by their output power, which is measured in WATTS. For example, 200 Watts peak power or 10 watts peak power. A standard wattage rating is the amount of power that a single solar panel will be able to overturn of bright sunlight in one hour peak time. Probably one of the biggest technical challenges to overcome with all photovoltaic (PV) installations, is the correct sizing of the system to meet the energy demands of the home, regardless of configuration.

Determining the appropriate size for your solar inverter is the most important factor for your solar inverter. The reason being is that your solar inverter converts direct current (DC) electricity coming from the array. To handle all the power the array produces, it must have the capacity.

Accurately sizing your solar power system is not as difficult as you may think. Knowing how many solar panels you will need as part of your solar array depends upon the amount of peak sun hours available per day and the actual energy consumption of your home. Also, what percentage of your home’s energy needs do you want to generate using your solar array.

Geographic Location


Your geographic location will also play a very important role in sizing your solar inverter due to its impact on the production of your solar panel system. Properties in Florida have higher solar irradiance (i.e. larger amounts of solar radiation) than properties in Seattle. A rooftop 6 kilowatt (kW) system in Florida should be able to produce more power than a system further north the same size.

These two systems will be producing different amounts of direct current DC electricity at any given time. The inverters needed to handle the electrical load can also be of different sizes. In areas with moderate temperatures and more sunshine, the inverters will be sized closer to the overall wattage (WATT) of the solar array so it can handle the maximum power output of the array at any given time. On the other hand, if your solar array experiences high temperatures or lower amounts of solar radiation that decrease panel efficiency, it’s less likely to produce that maximum power output defined by the direct current (DC) rating during standard testing conditions (STC) It is possible a smaller, undersized inverter may get the job done, in these scenarios.

Site-Specific Factors


The size of your solar inverter will be impacted by the site and design specifics of your solar array. The positioning and tilt of how your solar array is installed will affect the electricity production of your system. You also have to take into consideration environmental factors, such as dust, shade, etc. This will play a large role in how much sunshine the array absorbs.

All these considerations will be taken into account by the solar installers as well as equipment efficiencies, and more when estimating how much energy your solar panel system will produce overall. Everything will be taken into account to the overall derating factor of your solar system, which will be used to help determine what your solar panel system will produce in real-life situations. Solar panel systems that experience more shade are at a sub-optimal tilt, or facing east rather than due south have higher derating factors than systems on south-facing sunny roofs.

Solar panel systems with higher derating factors will not reach their full potential of energy output and as such can afford smaller inverter capacities relative to the size of the array.

Calculations for solar inverter sizing, How do I Calculate the size of my solar inverter?


To a certain extent, the size of your solar inverter can be smaller or larger than the DC rating of your solar array. The array-to-inverter ratio of a solar panel system is the direct current (DC) rating of your solar array divided by the maximum alternating current (AC) output of your inverter. If your array is 6 kilowatt (kW) with a 6000 watts (W) inverter, the array-to-inverter ratio is 1. If the same-sized array is installed with a 5000 inverter, the ratio is 1.2. Most installations will have a ratio between 1.15 to 1.25, inverter manufacturers and solar system designers wouldn’t recommend a ratio higher than 1.55.

A higher array-to-inverter ratio may work for your system if your solar panels aren’t producing at their maximum power output due to the mentioned factors above. The benefit of oversizing your solar array relative to the inverter capacity is that lower-wattage inverters will be cheaper than the larger inverters. But it’s not recommended to have an oversized array because it can cause clipping. Clipping will happen when your solar panels are producing too much direct current (DC) for the inverter to process. This will result in power losses from your solar panel system because the inverter will limit the amount of energy it’s converting.

But you don’t want to install a larger than needed solar inverter (i.e. has a lower array-to-inverter ratio) because your inverter is going to be running to its highest standard when it’s close to its overall capacity. If the inverter is too big compared to the array, the desired amount of electricity won’t be produced.

Solar Inverter Problems


With the solar inverter being the most sophisticated part of any grid-tie solar system, unfortunately, it's also the part you are most likely to have issues with. This doesn't really come as a surprise when the inverters are usually located outside in harsh weather conditions. This obviously includes humidity, rain, and changes in temperature, while producing thousands of watts of power for up to 10 hours a day. This is why it's important to mount it in a sheltered location if possible and to use a quality inverter.

It is likely that many inverters mounted outdoors will experience a fault at some point during their lifetime, due to extreme variations in humidity and temperature. However, the life of a solar inverter can be increased significantly by just locating it inside a garage, under a carport, and out of direct sunlight. It can make a lot of difference.

Over time solar panels can also develop problems that can result in poor performance, but unlike a faulty inverter, this will generally not result in complete system shutdown. With this in mind, it is worthwhile paying the additional cost for a reputable manufacturer (one which has been in good business standing for 5+ years and with extended warranties if available.

Warranty and Service


If you are having any issues with any solar products while it is still under warranty, you should first contact your solar retailer in order to have the product replaced or repaired. If you're having difficulty contacting your retailer, contact the manufacturer of the product. There is no reason why they shouldn’t be provided on the warranty documentation. Always give the warranty a read. Remember you paid for it.

If you would like to speak with one of our professional installers just give us a call. We will be more than happy to help you with any query.