Optimisers
Optimisers are module-level DC-DC converters that run MPPT on each photovoltaic module separately, so partial shading, several roof orientations or one ageing panel no longer drag down the whole string. Choose by architecture: SolarEdge optimisers are mandatory on every module and only work with a SolarEdge inverter, while Tigo optimisers are fitted selectively to the affected modules and run with almost any inverter. Match each unit to the module's power, Voc and Isc. Microinverters are the AC alternative. Guide
Thanks to the powerful optimiser, it is possible for each panel to produce the maximum amount of energy, regardless of the other panels in the system. This includes solutions like Tigo optimisers and SolarEdge optimisers that are commonly used in the industry.
The powerful optimisers thus optimise the solar energy production for each panel by tracking the point of maximum output, focusing on each panel in the system separately.
- Panel-level optimisation: a powerful optimiser is connected to the individual PV panels in the PV system. Its task is to monitor the power and voltage of each panel independently. This allows maximum performance from each panel, even when they are exposed to different conditions.
- Minimising power loss: when a panel in the system is shaded or has reduced power for other reasons, the power optimiser works to minimise these losses by adjusting the operating point of that particular panel. This ensures that even when some panels are not in optimal conditions, overall system performance remains high.
Product sorting
List of products
Listing controls
Related optimiser categories
Optimisers: module-level MPPT, safety and monitoring
A power optimiser is a small DC-DC converter bolted to the module frame and wired between the module and the string. It tracks the maximum power point of that one module and then converts its output to whatever voltage and current the string needs. Because each module is regulated independently, the string no longer works down to its weakest member, which is exactly what happens in a conventional string where bypass diodes only limit the damage inside the shaded panel.
The two systems stocked here take opposite approaches. SolarEdge moves MPPT out of the inverter entirely, so optimisers are part of the architecture and every module needs one. Tigo keeps the inverter's own MPPT and adds optimisation only where it is needed, which makes it the practical choice for retrofits and for arrays where just a few modules are shaded. Both add module-level monitoring and module-level shutdown as a side effect of the same hardware.
FROM THE FIELD
"The question I get most often is whether to optimise the whole roof. On a clean, unshaded, single-orientation roof the honest answer is no: you are paying for hardware and adding one more failure point per module to recover losses that were never there. Optimisers earn their keep on chimneys, dormers, trees and roofs facing two or three ways."
Ladislav Proc · Photovoltaics specialist, ONSA Plus
How to choose optimisers
Optimisers are not a general upgrade, they are a fix for specific problems: partial shading, several roof orientations on one MPPT input, and modules that no longer match each other because of age or replacement. Establish that one of those applies before you specify anything.
Then work through it in this order: decide the architecture (SolarEdge system or Tigo add-on), decide how many modules actually need a unit, and finally check the optimiser's input power, Voc and Isc limits against the module datasheet and the string rules against the inverter.
Show the full guide Close the guide
What module-level MPPT actually fixes
In a conventional string the modules are in series, so they all carry the same current. A module that is shaded, soiled or degraded pulls that current down for everyone. Optimisers break that link by converting each module's output individually.
- Partial shading: chimneys, dormers, satellite dishes, aerials and trees that shade two or three modules for part of the day. This is the classic case and where the yield gain is largest.
- Several roof orientations: east and west pitches, or a pitch plus a garage roof, that would otherwise need separate MPPT inputs or separate inverters.
- Mismatched or ageing modules: a replacement panel of a different output or age dropped into an existing string, or modules that have drifted apart after fifteen years.
- Awkward string lengths: roof shapes that leave you with an odd number of modules that will not form two balanced strings.
SolarEdge: optimisers as part of the architecture
SolarEdge splits the inverter in two. MPPT happens in the optimiser on each module, and the inverter only converts a fixed DC bus voltage into AC. That is why an optimiser is mandatory on every module in a SolarEdge system: leave one out and the string voltage never reaches the operating window. In exchange you get long strings, strings of unequal length, several orientations on one string and per-module data without any extra hardware.
- Whole-array design: plan the optimisers with the SolarEdge inverter from the start, and respect the minimum and maximum module count per string and the maximum string power.
- Not portable: SolarEdge optimisers do not work behind a third-party inverter, and a third-party inverter cannot be dropped into a SolarEdge array later.
- Safety by default: with the inverter off or disconnected, each optimiser drops its output to a low safety voltage, so the DC cabling on the roof is no longer at full string voltage.
Tigo: selective retrofit on almost any inverter
Tigo units sit between the module and the existing string and stay transparent when they are not needed. The inverter keeps its own MPPT, so the array works as a normal string array and the Tigo units simply correct the modules that are underperforming. That makes them the tool of choice for an existing installation where only part of the roof is affected.
- Fit only what is needed: equip the shaded or mismatched modules, typically together with a matching number of paired modules in the same string, and leave the rest untouched.
- Inverter agnostic: works with common string and hybrid inverters, so you are not locked into one manufacturer.
- Gateway required for data: per-module monitoring and remote shutdown need the Tigo communication kit and the relevant Tigo accessories, not just the optimisers themselves.
Tip from practice
Check the optimiser against three numbers on the module datasheet, not one: rated power in Wp, Voc at the lowest expected temperature and Isc. Modern high-current half-cut and TOPCon modules can exceed the input current limit of an older optimiser generation even when the wattage looks comfortable.
Rapid shutdown and module-level safety
Without module-level electronics, DC cabling on the roof stays live at full string voltage whenever the sun is up, even with the inverter switched off. Optimisers change that: on command, or when communication with the inverter is lost, each unit drops its output to a low voltage of about 1 V per module. Where a local rule, a network operator or an insurer requires rapid shutdown or a firefighter switch, this is usually how it is delivered. Confirm what applies in your country before you quote, because module-level shutdown is mandatory in some markets and merely recommended in others.
Module-level monitoring
Both systems report voltage, current, power and temperature per module to the manufacturer's portal. That turns a vague complaint about lower yield into a specific answer: which module, since when, and how much. For service work it also means you can locate a failing panel, a dirty panel or a loose MC4 connector without climbing on the roof. See monitoring for the gateways, meters and communication modules that feed the same portals.
Matching the optimiser to the module
Every optimiser has a maximum input power, a maximum input voltage and a maximum input current, plus limits on the string it feeds.
- Maximum input power: must be at or above the module's rated Wp. Units for 400 to 500 W residential modules will not cover 600 W and larger commercial formats.
- Maximum input Voc: compare against module Voc corrected to the lowest local temperature, not the value printed for 25 °C.
- Maximum input current: the constraint that catches people out on high-current modules.
- Two modules per unit: some models accept a pair of modules on one optimiser. That is cheaper, but the pair is then optimised together, so do not put a shaded and an unshaded module on the same input.
- String rules: minimum and maximum module count per string and maximum string power still apply, and they come from the inverter datasheet.
When optimisers do not pay off
On a clean, unshaded roof with one orientation and one set of identical modules, optimisers add cost, add a conversion stage and add one active component per module in the least accessible part of the building. The yield gain in that situation is small, and it can be cancelled by the optimiser's own conversion losses. Spend the money on a better inverter, on more modules or on a battery instead. Optimisers pay off when there is a real mismatch to correct, or when module-level shutdown or per-module monitoring is a requirement in its own right.
Optimisers compared
| Aspect | SolarEdge optimisers | Tigo optimisers |
|---|---|---|
| Coverage | Mandatory on every module in the array | Selective, only on the affected modules |
| Inverter | SolarEdge inverter only, MPPT sits in the optimiser | Works with most string and hybrid inverters |
| Typical use | New installation designed around the system | Retrofit and partial shading on an existing array |
| Monitoring | Per module through the SolarEdge portal, no extra gateway | Per module through the Tigo portal with a communication kit |
| Shutdown | Low safety voltage per module when the inverter is off | Module-level shutdown with the matching safety units and gateway |
Swipe the table to the left
Frequently asked questions about optimisers
What does a solar optimiser actually do?
It is a DC-DC converter fitted to one module that tracks that module's own maximum power point. Because each module is regulated independently, a shaded, soiled or degraded panel no longer limits the current of the whole series string.
Do I need an optimiser on every module?
With SolarEdge, yes: MPPT lives in the optimiser, so every module in the array needs one for the system to work at all. With Tigo, no: you fit them only to the modules that are shaded or mismatched and leave the rest of the string as it is.
Can I use SolarEdge optimisers with a different brand of inverter?
No. SolarEdge optimisers are designed to feed a fixed DC bus into a SolarEdge inverter that has no MPPT of its own. For a third-party inverter use Tigo units instead, which keep the inverter's own MPPT in charge.
Are optimisers worth it on an unshaded roof?
Usually not. On a clean single-orientation roof with identical modules there is little mismatch to recover, and the optimiser's own conversion loss can offset the gain. They pay off with shading, several orientations, mixed or ageing modules, or when module-level shutdown is required.
Can I add optimisers to an existing installation?
Yes, with Tigo. The units go between module and string and the existing inverter keeps working normally, so you can equip just the problem modules. Retrofitting SolarEdge is not practical, because it would mean replacing the inverter and optimising the whole array.
Do optimisers provide rapid shutdown?
Yes. On command or on loss of communication each unit drops its output to roughly 1 V, so roof cabling is no longer at full string voltage. Whether module-level shutdown is mandatory depends on national rules, the network operator and the insurer.
How do I match an optimiser to my modules?
Compare three datasheet values: the module's rated power against the optimiser's maximum input power, its Voc at the lowest expected temperature against the maximum input voltage, and its Isc against the maximum input current. High-current half-cut modules often hit the current limit first.
Optimisers or microinverters?
Optimisers keep a central inverter and optimise on the DC side. Microinverters convert to AC at each module, so there is no high-voltage DC on the roof and no single inverter to fail. Microinverters cost more per Wp and put all the electronics on the roof.
Can two modules share one optimiser?
Some models accept a pair of modules on one unit, which lowers cost per module. The pair is then optimised as a single unit, so only pair modules that see the same conditions. Never pair a shaded module with an unshaded one.
Do optimisers let me see the output of each panel?
Yes. Both systems report voltage, current and power per module to the manufacturer's portal, which makes it possible to identify a failing, dirty or shaded panel from the ground. Tigo needs its communication gateway for this, SolarEdge does not.
Whether module level electronics pay off depends on the shading, orientation and layout of the specific roof.
About ONSA Plus
Why installers across Europe buy optimisers from us
ONSA Plus is a European B2B distributor of photovoltaics, battery storage, heat pumps and EV charging stations. In our own EU warehouses we keep over 1,500 products from 25+ brands, including Huawei, Solis, SolaX and Dyness.
We are not just a trading company. We design and service energy systems ourselves, so we answer questions on shading analysis and module level electronics from engineering practice, not from a catalogue. You handle a warranty claim directly with us and you buy per job.
