We spend plenty of time talking with customers re the benefits of String and the benefits of Micros. Our team are big fans of the enphase micro inverter as evidenced by our appointment as Gold Level Installer but in some cases string inverters are the right solution for customers. Again quality product is the most important selection. Solar systems should work for 20-30 years, selecting the right equipment that is well fitted will ensure this.
Advantages of string inverters (DC)
Easy to troubleshoot
The main advantage of a string inverter is that you only need one of them to convert the DC electricity coming from your solar array to AC power. If anything is going to fail in a solar system, it is likely to be the inverter – making troubleshooting relatively easy when things go wrong.
Installing a single string inverter on a solar panel installation is cheaper than installing microinverters. Less labour hours are required, and string inverters are more affordable than microinverters.
Lower probability of wiring mishap
There are less connections between solar panels and the string inverter. Therefore, there’s a reduced chance that a string inverter setup will be improperly cabled, compared to a microinverter system.
They are installed at ground level so easier to fix and less exposed to the elements
Disadvantages of string inverters
Efficiency in partial shade
Since string inverters require solar panels to be wired in series, if one solar panel’s output is affected, the entire series of solar panels is affected in equal measure. This can pose a major issue if some part of a solar panel series will be shaded for part of the day.
All panels in a string need to be facing the same way so less flexibility in system design
More difficult system expansion
To get optimal performance from a string inverter, it needs to be working near its peak capacity. So, if you want to increase the size of your solar array at some point down the road, those panels will need to be routed to a separate string inverter, adding in additional complexity and cost.
String inverters are warrantied to last between 8 and 12 years, whereas microinverters can have a 25-year warranty.
Panel-level insight is not possible with a string inverter system, since there are no components affixed to the back of each panel to do the job.
While aggregate solar production is viewable, you won’t be able to see if there are individual panel performance problems that could be caused by a crack, defects, or debris.
Advantages of microinverters
The core advantage of using microinverters is that theoretically, you can yield more solar electricity. The reason for this is that there are slight differences in currents between solar panels. When solar panels are in a string, the current is reduced to that of the least-producing panel in the string. They also produce more power during the morning and evening as they have a lower start up voltage meaning less sun to get them working
Suitability for challenging installation conditions
If a solar system is facing multiple angles, meaning some panels are facing south, some east, and some west, then microinverters are the way to go. Or, if you have shading issues from trees or a large chimney, again microinverters would be best.
In these situations, the solar panels will be producing different amounts of electricity at different times of the day, but microinverters will ensure you harvest all of the energy, while with a standard inverter you will lose some of this production.
Microinverters can have 25-year warranties while standard inverters typically have 8 to 12 year warranties.
Microinverters and the add-on optimizers have the ability to track the production of each individual panel, while with a standard inverter you only can track the production of the whole system.
System expansion ease
If you were to expand your system in the future, microinverters are simple to add one at a time. Each panel and microinverter pair can be easily added to your existing solar array without needing to worry about purchasing, siting, and installing additional string inverters.
Safety With the Enphase micros there is no dangerous high-voltage DC running across your roof, only the same standard AC that powers your appliances.
Disadvantages of microinverters
The main disadvantage of microinverters is the price. They are typically $1,000 or so more expensive than a string inverter on a standard 5kW residential solar installation.
If one of your microinverters were to fail, not only would detecting which one has failed be a challenge, but once you did, servicing and replacing the component is not as easy as plopping in a new string inverter on the side of your house.
Your solar installer would need to again get up on your roof, work with your racking system, unbolt the solar modules, and replace the microinverter to re-establish AC conversion capability.
Amount of hardware on your roof
Since there’s a microinverter attached to every solar panel on your roof, that’s a lot of expensive metal equipment up there.