- What a microinverter does
- One module, two, or four
- Microinverter, optimiser, or string inverter
- What to read on the datasheet
- The ShineTong microinverter range
- Frequently asked questions
- What is a microinverter?
- Do I need one microinverter per panel?
- Are microinverters safer than string inverters?
- How do I choose the right microinverter?
- Can I add a battery to microinverters later?
- Sources
Match a microinverter to the module and to the grid before you compare efficiency. Count the inputs (one module, two, or four), keep the module’s voltage under the inverter’s DC maximum, and keep the module’s short-circuit current inside the input rating. Then match AC voltage, phase and the certificate for that country. A microinverter turns the panel’s DC into grid AC at the array. It does not fix a dark roof, and it is not automatically better than a string inverter on one clean, unshaded face.
The short version of when to choose it at all is in string inverter versus microinverter. This guide is the next step: what to read on the microinverter datasheet once that choice is made. How the conversion itself works is in how solar inverters work.
What a microinverter does
Each unit sits at the modules, takes their DC, and puts AC onto a trunk cable that runs to a breaker. A string inverter does the same conversion once, on the wall, after many modules have been wired in series. The house cannot tell which box made the sine wave. What changes is that a weak module no longer has to share a current with the others, and the long high-voltage DC string never gets built.
A shaded module does not “switch the whole array off.” Bypass diodes already skip a badly shaded section of a string. You lose that section’s power. The remaining problem is that one tracker can sit on a distorted curve and give up some power from the unshaded modules as well. A microinverter never asks those modules to share. A US Department of Energy Building America case study put the recovery of shading losses with module-level electronics at about 20% to 35% of the loss, and the recovery of losses from mixed roof directions at about 100% of that mismatch loss. Those figures are recovery of a loss in that study, not a promise that every roof will produce a third more energy.
The same case study is why rapid shutdown shows up in US design conversations. Module-level electronics can help a rooftop meet a rule that requires the array conductors to fall to a safe voltage when the system is shut down. That is a code and listing question for the country on the drawing. It is not a feature you can assume from the word “microinverter.”
One module, two, or four
The picture of one tiny inverter glued to one panel is incomplete. Current products are sold as one input, two, or four. The AC nameplate is the sum of what those inputs are allowed to deliver, not a suggestion of how many watts the roof needs.
| Inputs | What it is for | What goes wrong |
|---|---|---|
| One | A single module on a balcony, a shed, or a roof where every panel needs its own tracker | More boxes on the roof for the same array, and a module whose current exceeds that one input |
| Two | A pair of modules that can each run their own tracker while sharing one AC connection | Treating both inputs as one series string, or assuming every wattage in a “dual” family is legal on a plug-in circuit |
| Four | A small array that wants module-level tracking without a box per panel | Using it where the local rule caps feed-in far below the AC nameplate, or landing four high-current modules on an input that cannot take them |
A plug-in balcony is the sharp version of that last mistake. In Germany the simplified plug-in class stops at 800 VA from the inverter. A four-input unit rated 2,000 W to 2,800 W is a roof product. Sizing the inverter for a railing is a separate decision, written out in what size solar balcony system a house needs.
Microinverter, optimiser, or string inverter
An optimiser is not a microinverter. It adjusts the DC of each module and still needs a string inverter to make AC. Both are module-level power electronics, and both are aimed at shade, mixed directions and panel-level data. They are not interchangeable on a bill of materials. If the wall inverter fails, an optimiser system stops. If one microinverter fails, the other modules keep producing.
The string inverter is the better buy on one unshaded plane, with a serviceable box at eye level and no plan to add a scatter of panels later. It is also the natural place to attach a battery, because many hybrids have the battery port built in. Microinverters do not. A battery beside them is a second, AC-coupled inverter. Price that pair before you treat module-level AC as the premium system. The wider split between a house, a commercial roof and a utility plant is in how to pick a PV inverter.
Service belongs in the same sentence as the warranty. A failed unit is under a module. Someone has to lift that module. A 25-year warranty that does not say who climbs, and who pays for the climb, is a PDF. Many string inverters are warranted for far fewer years and are replaced at the wall in an afternoon. Neither fact makes the other product careless. Ask which failure you would rather have.
What to read on the datasheet
Take the lines in this order. Stop at the first one that does not fit. Efficiency is last because a unit that cannot be connected does not have an efficiency on your roof.
- DC voltage. The module’s open-circuit voltage at the coldest site temperature has to stay under the inverter’s maximum. A number that is safe at 25°C can be over the limit on a freezing morning.
- Input current. The module’s short-circuit current has to fit the input it is wired to. Newer modules are not gentle on this line. Confirm whether the published current is per input or for the whole unit. The datasheet of that SKU is the authority, not a family brochure.
- AC voltage, phase and frequency. A 220–240 V single-phase unit is the wrong box for a 120 V split-phase service and for a three-phase board it was not built to feed. Frequency is part of the same line.
- The grid certificate for the destination. A CE mark, a voltage range, or a sentence that says “suitable for global projects” is not permission to connect. The document has to name the model and the grid code.
- Enclosure and temperature. The rating has to match the roof, including the high end on a dark module in summer. IP67 means dust-tight and protected against temporary immersion when the unit is intact and the connectors are mated. It is not a permission to leave caps off.
- Monitoring. Panel-level data is useful the day a connector or a module fails and you can see which input went dark. If nobody will look, you are still paying for the radios.
- Efficiency, named properly. Peak lab efficiency, European efficiency and CEC efficiency are different tests. Do not compare a peak number on one brand with a CEC number on another. MPPT efficiency is not conversion efficiency. It says how well the tracker sits on the module’s best point, not how much AC leaves the terminals.
The ShineTong microinverter range
ShineTong builds microinverters only. We do not build string inverters, hybrids, off-grid inverter-chargers or utility central inverters. The three series on the microinverter page are below. Figures are the published catalogue values. A quotation should still name the SKU.
| ST-500M | ST-1200D | ST-2800Q | |
|---|---|---|---|
| Rated AC output | 500 W or 600 W | 800–1,600 W | 2,000–2,800 W |
| Max DC input | 60 V | 60 V | 60 V |
| Max input current | 14 A | 16 A | 20 A |
| AC output | 220–240 V | 220–240 V | 220–240 V |
| MPPT efficiency | >99.5% | >99.8% | >99.8% |
| THD | <3% | <3% | <2.5% |
| Operating range | −40°C to 65°C | −40°C to 65°C | −40°C to 70°C |
| Enclosure | IP67 | IP67 | IP67 |
The published maximum CEC efficiency is 97.5%, and only on the ST-2800Q GaN series. Do not paste that percentage onto the ST-500M or the ST-1200D. The product page states a 25-year warranty on these series. Grid approval is per destination: 220–240 V on the table is the voltage family, not a listing for every country, and it is not a 120 V US unit. Installation — bracket, trunk cable, polarity, breaker and commissioning — is the manual for the SKU on the roof, not a generic sequence. We do not publish a retail price.
For a distributor order, send the module datasheet, the country and the AC voltage. If the roof is one clean plane and the customer wants a hybrid on the wall, say that in the same note. We would rather decline the inverter than ship the wrong class.
Frequently asked questions
What is a microinverter?
A small inverter at the solar modules that converts their DC to grid AC on the spot. One unit may serve a single module, a pair, or four modules, depending on the model. The other modules keep producing if that unit fails. A string inverter converts the whole series string in one box on the wall.
Do I need one microinverter per panel?
Only if you buy a single-input model. Dual-input and four-input units are ordinary products. Each input still needs a module whose voltage and current fit that input. The AC rating is what the unit may deliver in total, and it still has to be legal on the circuit you are feeding.
Are microinverters safer than string inverters?
They keep the DC at the module, often to a maximum around 60 V, instead of a series string of hundreds of volts. That lowers the shock and arc exposure on the roof. It does not remove electrical hazard, and it does not by itself satisfy a rapid-shutdown rule. The listing has to say so for that model and that code.
How do I choose the right microinverter?
Fit the cold open-circuit voltage under the DC maximum, fit the module’s short-circuit current under the input rating, and match the AC voltage and the grid certificate to the site. Then compare warranties, who services a unit under a panel, and efficiency numbers of the same type. A peak efficiency on one sheet and a CEC efficiency on another are not a comparison.
Can I add a battery to microinverters later?
Yes, as an AC-coupled battery with its own inverter. The microinverters do not grow a battery port. If backup or self-consumption storage is already decided, price a hybrid string inverter against the microinverters-plus-battery pair before you commit. They are different bills.
