A fundamental part of every Solar Power set up is the Solar Inverter, it is a piece of equipment that is very important to understand.
After you read this definitive guide you will understand:
- What is a Solar Inverter
- How Inverters work
- Grid-Tied / Hybrid Inverters
- What Size Solar Inverter Do I Need?
- Solar Inverter Prices, How Much Do They Cost
- Best Solar Inverters In South Africa
What Is A Solar Inverter
Now we have that out the way let’s move on to the next part.
How Solar Inverters Work
Grid-Tied / Hybrid Inverters
The Solar Panels are connected directly into the inverter which then, in turn, plugs into your building electrical box (DB Board).
Hybrid inverters are used for Grid-Tied / Off-Grid / Storage and generator inputs. All different Solar Power applications are possible with Hybrid inverters, which is the most versatile option. Hybrid inverters accept DC and AC power .
Here are the general functions that a Grid-Tied / Hybrid Inverter typically perform:
- Synchronise to the grid
- Disconnect if the grid goes down
- Use an alternative power source (solar, battery or wind)
- Detect if any power sources are depleted and switch to another
- Monitor power usage
Here are the different types available:
String Inverters
Features
- Lowest solar inverter price
- Multiple MPPT inputs
- Provides backup power
The modern string inverter has improved over the years making it the most cost effective , the panels are wired in a series, simply put all the solar panels are connected together and is then connected into the inverter .
It’s a standalone box that is installed close to your fuse box and meter, the newer versions don’t tend to make much or any noise compared to older ones.
If you have an unshaded roof that gets 100% of the sun spread evenly and you have no shade from a chimney or tree the string inverter is perfect, but if there are obstructions it can cause the inverter to be less efficient .
Another factor is scaling, if your energy needs exceed your inverters output you will need to purchase a bigger inverter so scaling up can increase your overall solar inverter price. We suggest purchasing an inverter with a higher capacity just in case you need it.
Pros
- Efficient
- Affordable
- Long lasting (around 15 years)
Cons
- Not efficient if panel/s are shaded
- Expanding is difficult
Micro-Inverters
Features
- Easy to install
- Expandable
- Maximises output of each panel
These small inverters are connected to the solar panel itself, they are easy and safe to install. They can produce up to 25% more energy maximising the solar panel output .
Ideal for expanding the Micro-Inverter monitors (module-level monitoring) each panel independently making them operate independently , they are the better option when dealing with rooftops that have different pitches and partly shaded. Because each panel is independent it maximises each panel which means if there is a shaded or low-efficient panel it won’t hinder the rest of the group of panels (solar array) as the string inverter does.The downsides to these variations are the price, although they have come down they are the more expensive route.
Pros
- Easy to install
- Long lasting (25-year warranties)
- Expandable and modular
Cons
- More expensive
- Maintenance requires rooftop access
- Exposure to the elements can cause issues (extreme cases)
Solar Optimisers
The Solar Optimiser works with a String Inverter and performs much like the Micro-inverter by maximising the output of the Solar Panel (More about Solar Panels here).
Features
- Works with String Inverters
- Performs in the same way as a Micro-inverter
- Affordable
These components are perfect if you already have a String Inverter or if you know which Solar Panels are shaded or pitched differently. They are connected to the panel itself much like the Micro-inverter .
Pros
- Easy to install
- Long lasting (25-year warranties)
- Expandable and modular
Cons
- Maintenance requires rooftop access
- Exposure to the elements can cause issues (extreme cases)
Off-Grid Solar Inverters
Unlike the Grid-Tied Inverter options, an Off-Grid inverter requires batteries, the power from the Solar Panels charge the batteries directly then the battery power is then inverted to AC from DC batteries.
Off-Grid systems are more complicated, this is due to the extra components you will need such as the Charge Controller, Battery Monitors Circuit Breakers, Surge Suppressors and so on.
Here are the different types of Off-Grid inverters available:
Pure Sine wave
Features
- Delivers quality power output
- Quieter than Modified Sine wave
- Ideal for modern appliances
A safer option the Pure Sine inverter is the main choice for Off-Grid, affordable and deliver higher quality output. Almost all appliances will work with these inverters making them highly compatible with most systems.
Modified Sine wave
Features
- Lowest price
These solar inverters output lower quality power and are only compatible with certain appliances. They can be problematic for electronic equipment, we recommend Sine wave inverters .
What Size Solar Inverter Do I Need?
The capacity speaks to the max DC energy can be fed into the inverter, while the output speaks to the max AC current you’ll be using to power your home. For example, if you buy a 3kW converter, but your panels are only capable of delivering 1kW, there’s an imbalance .
If you plan on adding more panels, then you’ve made a pretty good investment. However, getting 3kW from your panels while your inverter can only handle a 1kW output seems like somewhat of a waste. You’re not using your system to its full benefits .
Work out what appliances you will be running
Typical households that run the standard number of appliances such as these:
| Appliance | Watts (per hour) |
|---|---|
| Standard Fridge | 150 |
| Fridge Freezer | 150 |
| Washing Machine | 1000 |
| Tumble Dryer | 2800 |
| Personal Computer | 200 |
| 46″ LCD Flat screen TV | 250 |
| Modem | 12 |
| Alarm System | 15 |
| 12 LED Lights | 240 (20 Watts Each) |
| DSTV Decoder | 30 |
| Total: | 4847 watts |
In the example above you can work out that the inverter will need to cover these appliances, this equates to 5kw (rounded up).
We also add an extra 1kw to ensure we cater for any additional appliances that might be added in the future which takes us to 6kw .You might be thinking that this is already a large system, but…
If you purchase an inverter with dual MPPT outputs you can split that load in 2.
- 2800 watts (2.8kw) for the Tumble Dryer and Washing Machine – Non-essential.
- 2047 watts (2.1kw rounded up) for the rest – Essential.
The ability to have to Essential and Non-essential load outputs allows you to prioritise your energy, bundling them all together is not only going to push up the price of your inverter (because you need a larger one), it also gives you the option to only use your batteries exclusively on the essential load , driving down the cost of storage needed.
What does this mean?
It means that your inverter size comes down, so instead of a 6kw Inverter to handle it the complete load, you can get a 4kw or a 5kw inverter instead.
Here’s an example of a 4.6kw kit that handles the above with some room to spare:
Goodwe – Lithium Storage 3.92kwh – Solar Power Kit
System Specs:
- NRS approved (National regulation standards) and on the approved list of inverters for most SA municipalities
- Array size: 2970W (peak hours)
- Est daily production: 16.35kwh
- Storage: 3.96 kwh for daily usage
- Peak load: 4.6kw
- Annual yield: 5886kwh
- Grid-tie / off-grid / grid support
In conclusion…
After working out what size you think you need simply double check with our team at SolarAdvice to make sure, don’t forget that advice is always free.
Solar Inverter Prices, How Much Do They Cost?
Grid-Tied Inverters
Here are our Grid-Tied inverters and their prices, they all vary depending on size and manufacturer.
Single Phase Grid-Tied Options
3 Phase Grid-Tied Options
Hybrid Inverters
Micro Inverters / Power Optimisers
Best Solar Inverters in South Africa
To name the best pound for pound brand of Inverter is tricky, each brand does have its strengths and weaknesses depending on its application.
Here are the best inverters that we would recommend:
- Goodwe – this brand is of great quality and a great price
- SolarEdge – a wide range of inverters available and great quality
- SMA – aesthetically great looking and compact
- Solis – efficient Grid-Tied options
- Steca – solid German engineering, compact and innovative
Resources:
https://en.wikipedia.org/wiki/Solar_inverter
SolarAdvice Rating
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User Review
( votes)Solar Inverter Review Summary
Depending on what type of inverter you choose the experience can differ greatly, for such an important component it’s safe to say that we rate the Solar Inverter high.
Inverters have improved over the years and they’re only getting more reliable, cheaper, easier to install with improved monitoring features.
Consult with a technician before purchasing your inverter just to make sure it suits your needs.
Pros
Enables system monitoring
Affordable
Expandable (Micro-inverters)
Long lasting
Cons
Expensive for larger systems
Can vary depending on manufacter
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