Microinverters and Power Optimizers: A Shaded-Roof Solution

A microinverter is a small inverter fitted behind each solar panel that runs that panel independently. A power optimizer, on the other hand, is a DC-DC converter fitted to each panel and works together with a shared string inverter. Both have the same aim: to prevent a single weak panel from dragging down the whole array in shaded-roof solar panel arrays. In this article we compare the two solutions with the classic string inverter and explain when each makes sense on Antalya roofs.

What is a microinverter and how does it work?

In a classic system, panels are connected in series to form a string, and this string goes to the MPPT input of a single inverter. In a microinverter system, there is a small inverter behind each panel. The panel's direct current is converted to alternating current right behind the panel, and the cables running across the roof carry alternating current.

Because each panel works with its own MPPT, shading, soiling or failure of one panel does not affect the others. Panels facing different directions also work without problems in the same system. Since there is no large DC string voltage, the direct-current voltage on the roof is low.

• Independent MPPT and production tracking per panel.
• The ability to use panels with different orientation and tilt in the same system.
• No high-voltage DC cable on the roof.
• The number of devices rising as the number of panels rises.

The practical result of this structure is as follows: in a home whose roof has surfaces facing east in the morning and west in the afternoon, each panel follows its own production curve. Because many villa roofs in Antalya consist of two or three different surfaces, this feature is valuable on complex roofs in particular. By contrast, on a single-direction, wide, shade-free roof, this flexibility can often be an unnecessary extra cost.

What is a power optimizer and how does it differ from a microinverter?

A power optimizer is also fitted to each panel, but it does not convert direct current to alternating current. It adjusts each panel's output voltage and current so that the panel works at its maximum power point, and passes this on as a DC output compatible with the shared string inverter's input voltage. The conversion is still done in a single central inverter.

An optimizer system has panel-level monitoring and shade management, but the inverter is still a single point. In a microinverter, each panel has its own converter, and when one device fails, only that panel drops out.

String inverter, microinverter and optimizer compared

It would not be right to say which solution is better in general. Without shade, a string inverter is enough in most projects in terms of cost and simplicity. We covered general inverter types in our what is an inverter and its types article.

The effect of shade on production: a simple calculation

In a series-connected string, current is limited by the weakest panel's current. Let us see this with a simple example. Suppose 10 panels of 605 W form an array of 6.05 kWp in total. Suppose one panel falls in shade and its current drops to half, and let us use a simplified model in which the bypass diodes do not come into action.

• String inverter: String current can fall by half; array power drops to about 3.0 kW. The loss is about 3.0 kW.
• Microinverter or optimizer: Only the shaded panel works at half power; the loss is about 0.3 kW (half of 605 W).

This is a calculation, not a measurement. In reality, bypass diodes, the half-cell panel structure, the shape of the shadow and the inverter's MPPT behaviour change the result; half-cell panels work in a more controlled way in partial shade thanks to two parallel sub-strings (we covered this in our half-cut panel article). Even so, the example shows why panel-level management stands out on shaded roofs.

In Antalya, shade generally comes from these sources:

• Water tanks, solar water heaters, outlets and lift towers on apartment roofs in Kepez and Muratpaşa.
• Chimneys, skylights and the shadow of a neighbouring building on tile roofs.
• Mature trees and high walls in villa gardens in Döşemealtı, Belek and Manavgat.
• Lengthening shadows in winter: according to PVGIS data, specific yield in Antalya in December and January is only 99 kWh/kWp, so the share of shade rises at low sun angles.

You can find general information about shade in our the effect of shading on solar panels article.

Monitoring and fault detection

One of the most concrete benefits of panel-level solutions is that each panel's production can be monitored separately. If a panel is soiled, shaded or faulty, it is immediately visible on the app screen. In a classic string system, on the other hand, you look at the string's total value, and to find the weak link you need to take measurements on the roof or look into the causes of efficiency loss. Even so, monitoring data alone is not a solution; the data needs to be read regularly and turned into a maintenance decision.

Adding an optimizer to an existing system later

If a shade problem has appeared after installation, in some cases an optimizer can be added to the existing string system. This option applies only to compatible inverter and optimizer product pairs, and technical suitability must be verified from the manufacturer's documents. When replacing equipment in an old system, also bear in mind that under the unlicensed rule new main equipment must have been manufactured within the last five years.

Cost items, maintenance and life

We do not give prices here, because prices vary by brand, model and period. When comparing quotations, look at these items:

1. Number of devices: Because microinverters and optimizers go per panel, a 20-panel system means 20 devices.
2. Central inverter: An optimizer system also needs a string inverter; a microinverter system needs a separate communication or data gateway.
3. Installation time: Additional connections are made for each panel.
4. Maintenance and replacement: A large number of electronic devices working on the roof means climbing onto the roof in the event of a fault.
5. Warranty: Microinverter and optimizer warranties vary by manufacturer; the datasheet and warranty document should be requested separately. For example, the standard on-grid inverter warranty at TommaTech is 5 years from the invoice date.

Summer temperatures in Antalya reach an average maximum of 34.2 °C in July (MGM, the Turkish State Meteorological Service). Electronic devices fitted behind the panel work in an environment close to panel temperature; for this reason the device's operating temperature range and protection class (IP) should be checked from the datasheet. In addition, as the number of devices on the roof rises, ease of access and monitoring also matters.

Which makes sense in which situation?

Reducing shade from the start is often more economical than buying extra electronics: solutions such as moving the panel to a shade-free area, rearranging obstacles on the roof or pruning the tree in the garden should be tried first. We covered roof orientation and tilt decisions in our solar panel tilt and orientation in Antalya article. At the free site survey we can do a shading analysis of your roof together; you can book an appointment through our contact page.

Conclusion

Microinverters and power optimizers are two different ways of managing panels independently in shaded-roof solar panel arrays. On a shade-free, single-direction roof, a classic string inverter is usually the sufficient and simpler solution. If there is shade, multiple orientations or a need for panel-level monitoring, panel-level solutions make sense. Before deciding, try ways to reduce shade, take the number of devices and maintenance access into account and read the warranty documents separately. Also remember that under the regulation, main equipment must have been manufactured within the last five years (the 2 April 2026 amendment).

#Technology#Microinverter#Power Optimizer#Shade#String Inverter#Roof