Solar Inverter Selection: Why We Only Carry Four Brands

January 19, Foshan solar warehouse. A light rain outside; inside, the year-end final batch of inverters, 120 units, stacked and waiting to ship to Mombasa and Lagos after the holiday.

The pandemic is in its third year, and space is still hard to book. Slots have to be grabbed ten days ahead, and a 40-foot container to East Africa is stuck around US$2,600. With cargo this hard to move, picking the right cargo matters even more: ship one wrong unit and the round-trip freight costs more than the machine itself.

The day before, a Kenyan customer asked me on video: the market is full of inverter brands, why do you only carry four? I have been asked this for five years. This piece is the full answer, once and for all.

Why Only Four Brands

In 2019 I chased a cheap price. An inverter from a small Guangdong factory quoted eighteen percent below the big brands, over US$10,000 saved on thirty units. I bought thirty and shipped them to Tanzania.

Six months later, four had failed. The factory said to send them back for testing: US$1,400 round trip per unit, and the customer would wait forty-five days. Unacceptable. We replaced them with new machines outright: four machines plus freight, 26,000 yuan lost.

That factory quit exporting the following year; after-sales email canceled, phone disconnected. Since then I have had a rule: only brands in the global top ten by shipments, with spare-parts points overseas.

That filter leaves four: Huawei, Sungrow, Growatt, Solis. It is not that other brands are bad; it is that my customers are spread across nine countries, and when a machine dies at a mine in Zambia, I have to be able to find someone to fix it.

Take parts. Sungrow has an agent in Kenya; common parts arrive in three days. Huawei has a parts warehouse in South Africa; one week to East Africa. A small factory's parts disappear into the void the moment they are mailed.

DC/AC Ratio Is Not "the Bigger the Better"

The DC/AC ratio is total solar PV module power divided by the inverter's rated power. We generally configure 1.1 to 1.25.

In 2021 one customer, using an installer he found himself, paired 130 kW of modules with a 100 kW inverter, a ratio of 1.3. Four months after installation he came to me: midday generation would not climb; he was losing over 2,000 kWh a month.

I checked the local irradiance and the tilt angles. The problem was the match: local sunshine is so strong that midday module output overwhelmed the inverter, and the excess was clipped. We added a 50 kW unit to split the load, and generation recovered that same month.

Going the other way does not work either. 100 kW of modules on a 100 kW inverter looks neat, but full-load hours at midday are few across a whole year, and the inverter runs underfed. Undersize and you waste modules; oversize the array and you clip the peak. This number is calculated, not guessed.

MPPT Count and Grid Adaptability

The MPPT count is, simply, how many independent strings the inverter can track. If the roof has shading or modules face different directions, too few MPPTs cost you.

That Kenyan customer's warehouse roof has six exhaust stacks whose shadows sweep across two rows of modules at ten in the morning and three in the afternoon. I chose a six-MPPT unit for him: the two shaded rows run on their own two channels, and the rest are unaffected.

Grid adaptability matters even more. In Nigeria, on a bad day the grid goes down four or five times. An ordinary inverter drops off-grid at every fluctuation and takes half a day to reconnect.

For machines bound for Nigeria, we have the factory widen the voltage tolerance window before shipment and set the low-voltage ride-through parameters to the local grid. Skip this step and the machine is a paperweight over there.

What Each of the Four Brands Is For

Huawei: big projects, commercial and industrial plants above 100 kW. Expensive, twenty percent over small brands at the same power, but the communications and monitoring are excellent; the customer can see every unit's generation on their phone.

Sungrow: 50 to 200 kW factory rooftops. Tough as nails, and the most spare-parts points in Africa.

Growatt and Solis: 3 to 20 kW residential and small commercial. Good price, small size; over six hundred units fit in a 40-foot container, spreading freight to under US$4 per unit.

The four brands cover 3 kW to 250 kW. Bigger utility-scale projects, I do not take them. That is not our work.

How After-Sales Works

When a machine fails, the customer first sends me a photo of the fault code. Ninety percent of alarms can be cleared in a ten-minute video call; most are parameter or wiring issues.

When a part really needs swapping, the parts channels for all four brands are open. Last November a unit in Zambia reported an insulation fault; the factory confirmed remotely that it was the main board, the part shipped from the South Africa warehouse, and it reached the mine in nine days.

Within warranty, all four brands offer global coverage; tickets run through the factory's system and I can track progress. A small brand's warranty rests on one person's promise over WeChat, and when that person quits, the promise quits too.

Before shipping, every inverter in the warehouse is powered on for a self-test, and the serial number is photographed, archived, and sent to the customer with the packing list. Once the machine arrives, report the serial number at installation; warranty starts from that day.

If you want to buy, send me three things: your module list with wattage, drawings of the roof or ground site, and your local grid conditions, voltage level, how often outages happen. Email me those three and within two days you will get a selection sheet stating exactly which unit and why. If the match is wrong and your generation suffers, take this article and come find me.