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Solar Inverters – Pros, Cons & Costs

With the current state of energy prices, it makes more sense now than ever to invest in solar panels. 
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Solar Inverters – Pros, Cons & Costs

A solar inverter is a component of a photovoltaic (PV) system that acts as a connection point between your solar panels and your house. Before it can be used to power your building, all of the electricity that is generated by your solar panels needs to go through the solar inverter first.

Electricity produced by solar panels is known as direct current (DC), in contrast to the alternating current (AC) that is required by the vast majority of electronics and home appliances (AC). Every bit of DC electricity is transformed into AC electricity by the inverter.

Your solar panels are effectively nothing more than a collection of useless silicon plates if you don’t have an effective solar inverter to transform the electricity into a form usable in the home.

In addition to the essential AC/DC power conversion that must take place, the vast majority of solar inverters also provide some kind of monitoring, most frequently in the form of a mobile application. You will be able to monitor the amount of electricity generated by your solar panels and determine whether or not there are any issues with the solar PV system.

This will give you an idea of when the electricity production from your solar panels is at its highest point, which is the time of day when you should be conducting the majority of your daily electricity usage.

How Efficient are Solar Inverters?

The efficiency of a typical solar inverter ranges from 95 to 98%, which indicates that it loses between 2 and 5% of the electricity that it converts. This is to be expected given that an inverter will use some of the electricity that is supplied to it to maintain its own operational state.

In contrast to the efficiency of a typical solar panel, which ranges between 15 and 20%, the performance of solar inverters is significantly higher than that of their flat-panel equivalents.

Can Solar Panels Work Without a Solar Inverter?

No, even the solar panels that are currently on the market that are considered to be the most effective are effectively useless if they are not connected to a solar inverter.

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What Types of Solar Inverters Are Available for a Solar PV System?

To complement the solar panels that you have set up, there are three distinct varieties of solar inverters to choose from. These include string inverters, micro inverters and power optimisers. Below we outline the pros and cons of each type so you can make an informed choice when it comes to selecting which type of solar inverter will be best for your solar panel system.

  1. String Inverters

The least expensive of the three possibilities is a string inverter, which is also referred to as a centralised inverter. It operates by itself by processing the alternating current electricity that is generated by all of your solar panels. In the majority of installations, anywhere from two to fourteen solar panels are physically connected to one another to make up a “string.” This “string” then routes all of its generated electricity to a single inverter.

In addition, as you probably already guessed, this poses a significant problem for the string inverter. The output from each panel is directed through the same box, so it appears as though they are functioning as a single large unit and are normally located in a loft or garage.

The Advantages of String Inverters

Easy to Diagnose and Fix Any Problems.

The primary advantage of using a string inverter is that only one of them is necessary to change the direct current (DC) electricity that is produced by your solar array into alternating current (AC) power. When something goes wrong with a solar energy system, it is most likely to be the inverter, which makes diagnosis and repair of the problem relatively straightforward.

Cost

When it comes to installing solar PV panels, a single-string inverter is a more cost-effective option when compared to using multiple micro-inverters. There are a variety of micro inverters available, but string inverters have a lower labour requirement and a lower price point.

Reduced Chance of a Wiring Mishap

The solar panels and the string inverter are connected by a smaller number of wires than before. A micro inverter system is more likely to have incorrect cabling than a string inverter setup due to the nature of the micro inverters.

String inverter disadvantages

Less Efficient in Shady Areas

Since string inverters demand that solar panels be wired in series, the output of the entire series of solar panels is affected proportionally whenever one of the solar panels in the series has its output altered. If one section of a series of solar panels is shaded for a significant portion of the day, this can be a considerable problem.

System Expansion is More Challenging

To provide the best performance possible, a string inverter needs to be working at or very close to its maximum capacity. If you decide in the future that you want to increase the size of your solar array, then those panels will need to be routed to a separate string inverter, which will add both complexity and cost to the system.

Short Lifespan

Micro inverters come with a warranty that is good for 25 years, whereas string inverters come with a warranty that is usually good for 5 to 10 years, these can often be extended for an additional fee.

Limited System Insights

With a string inverter system, gaining insight at the panel level is impossible because there are no components fixed to the back of each panel that is designed to complete the task.

You won’t be able to tell if there are any individual panel performance issues caused by a crack, defect, or debris even though you’ll be able to see the aggregate solar production that’s being generated.

  1. Micro inverters

Micro inverters are similar to string inverters in that they convert direct current to alternating current, but instead of being strung together, microinverters are attached directly to individual solar panels. One of these micro inverters is about the size of a router. They are typically used on smaller solar arrays and are noted for being compact and therefore having space-saving benefits.

The primary difference between string inverters and micro-inverters is that micro-inverter-equipped solar PV systems will typically have the same number of micro-inverters as solar panels. This is in contrast to string inverters, which typically have fewer micro inverters than solar panels.

Micro-inverters do not have this limitation because they operate in a parallel circuit, unlike standard string inverters, which limit the amount of electricity each panel can produce to the amount produced by the lowest-producing panel on your roof.

A micro inverter will allow the production of each panel to be utilised to its full potential. The voltage of the grid will be converted to that of the power produced by each panel.

Advantages of Microinverters

Can Shutdown Quickly

To protect first responders and firefighters from being exposed to high voltage while they are on rooftops or servicing power lines, new electrical codes require rapid shutdown of solar power systems.

Micro inverters are capable of meeting these requirements for rapid shutdown, and this ability is built into each module of the device.

Additional Power

The most significant benefit of using micro-inverters is the potential to generate a greater amount of solar-generated electricity. The reason for this is that solar panels have slightly varying currents running through them. When solar panels are connected in a string, the current is reduced to that of the string’s least-producing panel.

Suitable for Difficult Installation Conditions

If a solar array has panels that face in multiple directions, such as south, east, and west, then microinverters are the most efficient way to convert the energy produced by the array. Micro inverters are the best choice for situations in which there is a problem with shading, such as when trees or a large chimney are present.

In these circumstances, solar panels will generate variable amounts of electricity at different times during the day. 

Shorter Lifespan

Standard inverters typically come with warranties that range anywhere from 5 to 10 years, while microinverters typically come with warranties that are good for 25 years. The reliability of micro inverters was called into question a few years ago; however, technology has since caught up with the industry, and the manufacturers of micro inverters now offer longer warranties, which demonstrates their confidence in their solar inverter products.

Panel-level Supervision

Standard inverters are only capable of tracking the production of the entire system, but micro inverters can track the production of each panel.

Easy System Expansion

It won’t be difficult for you to add micro inverters one at a time if you later decide to expand your system. Each micro-inverter can be added easily to your existing solar panel array without the need for additional string inverters to be purchased, sited, and installed. This is because adding a panel and micro inverter pair to your solar array is a plug-and-play process.

To summarise, microinverters are unquestionably valuable; however, you should only use them if you need to meet requirements for rapid shutdown, have panels that face multiple directions, or have issues with shading.

In most circumstances, the standard inverter that costs less money is going to be the more cost-effective option.

Disadvantages of Microinverters

High Cost

The high cost of micro-inverters is the most significant drawback associated with them.

When compared to the price of a string inverter for a typical 5 kW residential solar installation, they are significantly more expensive.

Maintenance

If one micro-inverter goes wrong it would be difficult to determine which one has broken.  Servicing and replacing the component will not be as easy as attaching a new string inverter to the exterior of your home.

In order to re-establish the capability of AC conversion, your solar installer would need to climb back onto your roof, work with your racking system, unbolt the solar modules, and replace the microinverter. All of these steps would need to be performed in order.

The Amount of Hardware on Your Roof

Due to the fact that each solar panel has a micro-inverter attached to it, there is a significant amount of expensive metal equipment on your roof.

There is a possibility that micro-inverters could perform the role of lightning rods on a smaller scale. If you live in an area that is prone to storms and you own a historic wooden structure that has wooden roofing materials, you might want to rethink the decision to install them.

  1. Power Optimisers

The third choice is best described as a compromise between the first two. In point of fact, power optimisers can be applied to a string inverter to improve its overall performance.

A power optimiser, which performs operations analogous to those of micro-inverters, is built into each solar panel. Power optimisers do not convert the direct current (DC) to alternating current (AC); rather, they simply adjust the voltage of the DC electricity to “condition” it. The conversion is carried out in a more effective manner, in spite of the fact that the electricity is still directed to a centralised inverter.

The Advantages of Power Optimisers

You will be able to see a greater portion of the electricity that is produced by your solar panels.

It is possible to monitor the performance of individual solar panels.

Disadvantages of Power Optimisers

It is more expensive than purchasing a single-string inverter.

Because power optimisers continue to rely solely on a centralised inverter, your entire solar panel array will be turned off in the event that this component fails.

How Much Does it Cost to Buy a Solar Inverter?

Depending on the size of the solar energy system that you have installed in your home, the cost of a standard string inverter for residential solar panels will typically range anywhere from £500 to £1,500, depending on your requirements.

On the other hand, the cost of a micro-inverter ranges anywhere from £100 to £150 for each individual unit.

Power optimisers typically cost £40 each, but in addition to that, you will need an inverter, which can typically cost around £600.

As a consequence of this, if you possessed a solar photovoltaic (PV) system with a capacity of 3.5 kW and 10 solar panels, each of which had a power output of 350W, you would be required to pay either £1,000-£1,500 for 10 micro inverters or around £1,000 for optimisers, consisting of £400 for the power optimisers, plus an inverter at around £600.

Solar inverter costs are based on a typical 3.5 kW system consisting of 10 panels.

 Cost of the solar inverter (or equivalent)Is an inverter required at an additional cost?Overall Solar inverter set-up cost for a 3.5kW system
String inverter£500 – £1000No£500 – £1000
Microinverter£100 – £150 (per unit)No£1,000 – £1,500
Power optimiser£40 (per unit) x10Yes (£600)£1,000

Solar Inverters Pros and Cons Summary

Solar inverters are a vital component of a solar PV system and are needed to convert the current so it is ready to use to power your home. String inverters are usually the lower cost option than the others, such as micro-inverters or power optimisers.

Inevitably each of the solar panel inverter options has its advantages and drawbacks, including differences in how long they last. While a string inverter might need to be replaced within 10-12 years, a micro inverter system might realistically be expected to last up to 25 years. A solar expert can help you weigh up what is likely to be the best option for you.

It is worth bearing in mind that, along with the purchase and installation of the solar panels, the inverter is bundled into the cost of the solar PV system when it is purchased for the first time for a residential property. Therefore, you won’t need to worry about adding on any additional costs as the price of the inverter set-up will be included in any quotes for solar PV systems that you receive.

However, if you are needing a new solar inverter, either because your solar system is old or has broken down, then hopefully you are now better informed about the inverter options and potential costs. In any case, a trusted solar company will be able to help you get your inverter replaced and get your solar panel system functioning well again. 

 

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