Sungrow inverter review, from an installer

Reading a Sungrow model name

Sungrow's naming looks like alphabet soup on a quote until somebody shows you the pattern, and then it is obvious. There are two letters that matter.

SH means hybrid, so it runs solar and a battery. SG means solar only, with no battery input at all. That single letter is the most important thing on the quote, and it is the one people miss. If a quote says SG and also promises you a battery later, ask the question now, because adding storage to it later means either a second inverter or replacing the one you just bought.

After that the numbers are the kilowatts and the last letters are the supply. RS is single phase, which is most houses. RT and T are three phase.

So an SH10RS is a 10 kilowatt single phase hybrid, an SH10RT is the three phase version of the same size, and an SG30CX is a 29.9 kilowatt three phase machine with no battery input, which is a commercial scale solar only unit and not a home battery inverter however big the number looks.

Four MPPT trackers, and why Queensland roofs care

This is the specification I would put first, and it is the one almost no review mentions.

An MPPT tracker is an independent solar input. Each one works out the best operating point for the panels wired to it, on its own. The practical meaning is simple: every tracker is a roof face that can behave independently.

The SH8.0RS and SH10RS carry four independent MPPT inputs, at 16 amps each. Most single phase hybrids in this class carry two.

On a simple house with one big north facing roof, that is worth nothing and I will say so. On the houses we actually work on, it is worth a great deal. Queensland homes are rarely one clean rectangle. You get a hip roof with four small faces, or a north face half shaded by a neighbour's poinciana at 3pm, or an east and west split because the north face is all skylights and solar hot water. With two trackers you compromise: you gang faces together and the weakest one drags the rest down. With four you wire each face to its own tracker and the shaded one shades only itself.

It is also the difference between a system that can grow and one that cannot. Adding a few panels on a different face later is a wiring change, not an inverter change.

Double the solar on the same inverter

Sungrow recommend a maximum solar input of 20,000 watts of panels on the SH10RS, and 16,000 watts on the SH8.0RS. That is twice the inverter rating, and it is unusually generous.

The old rule of thumb, that an array may be at most a third larger than the inverter, comes from the Clean Energy Council guidelines for grid connected systems with no storage. It does not bind a battery system. Solar Accreditation Australia's guidelines allow you to go past it on a battery system where the inverter manufacturer permits it, and STCs are claimable on the whole array.

What that buys you is winter. An oversized array does not help much at noon in January, when the inverter is already at its ceiling and clipping the top off the curve. It helps enormously at 8am in June, on a cloudy day, and in the shoulder hours either side of the peak, which is exactly when a battery is trying to finish charging. On a big roof it is a lot of extra generation for no extra inverter.

The honest limit: you are trading a small amount of clipped summer midday output for a much larger amount of winter and shoulder output. On almost every house we model, that trade is worth making. On a house with a small roof it is moot.

Whole home backup at 63 amps, with nothing extra on the wall

Backup on a Sungrow hybrid lives inside the inverter. There is no separate gateway box to buy, to find switchboard space for, or to pay an electrician to wire.

The numbers from the manual, for the single phase SH8.0RS and SH10RS: the backup port is rated at 14,500 watts and 63 amps while the grid is up, and the switch to emergency mode is under 10 milliseconds. Off grid it runs 8,000 or 10,000 watts continuous depending on the model, and peaks at 13,680 VA for 10 seconds to get motors started.

Ten milliseconds matters more than it sounds. It is fast enough that nothing in the house notices. Your computer stays on, the oven clock does not reset, and the internet does not drop. Systems that take half a second are technically doing backup, but you feel every one of them.

Sixty three amps is the figure to hold on to, because it is genuinely whole home rather than a handful of essential circuits. That said, the manual is blunt about the condition attached, and so am I: the loads you connect must not exceed the backup rating. A house with ducted air conditioning, an induction cooktop and a pool pump can exceed 14.5 kilowatts without trying. Whole home backup means the whole board is fed, not that you can run everything at once during a blackout.

The other honest limit is the battery, not the inverter. Maximum discharge is 50 amps, around 10 kilowatts. The inverter can pass 63 amps to the house, but only while the battery and the sun between them can supply it.

It retrofits onto solar you already own

This is the feature I end up explaining most often, and it is buried in section 2.8 of the manual where nobody reads it.

The Sungrow hybrid is compatible with any single phase PV grid connected inverter. Not any Sungrow inverter. Any brand.

So if you have a working 6.6 kilowatt system from 2019 on some inverter nobody stocks any more, you do not have to throw it away to get a battery. The existing inverter keeps running and the Sungrow hybrid is added alongside it. Its generation feeds your loads first and then charges the battery.

There are two ways to wire it and they are not equivalent. Tied to the hybrid's grid port, the old system stops when the grid stops. Tied to the hybrid's backup port, the old solar keeps generating during a blackout, which is the arrangement you want if outages are a real concern where you live, and it is the one most installers do not offer because it takes more thought. The condition is that the old inverter's rated power must not exceed what the battery can absorb.

Worth saying plainly: this is the inverter that retrofits, not the battery. Sungrow's SBH and SBR batteries pair with Sungrow hybrids and not with other brands. If you want the fuller comparison of the two ways to add storage, I wrote it up in hybrid inverter versus an AC coupled battery retrofit.

The three phase end of the range

On three phase the range runs from the SH5T up to the SH25T at 25 kilowatts, which is the largest three phase hybrid Sungrow build for homes.

The SH25T takes up to 50 kilowatts of solar, again double the inverter, across three MPPT trackers. Peak efficiency is 98.2 percent. Backup is the same architecture as the single phase units, a built in 63 amp bypass, up to 43 kVA, switching under 10 milliseconds, and it supports 100 percent unbalanced output both on grid and off, which genuinely matters on a three phase house where all the big loads happen to sit on one phase.

Two things to know before you get attached to it. First, it is a 25 kilowatt inverter, not 29.9, so it does not max out the 30 kilowatt cap Energex and Ergon apply to a three phase connection. Sungrow do build a 29.9 kilowatt three phase unit, the SG30CX, but as above the SG means solar only, with no battery. If filling your whole 30 kilowatt allowance is the point, Sungrow is not the brand for it.

Second, and this is where the SH25T earns its place: it carries a C5 corrosion rating, the highest there is, alongside IP65. On the Sunshine Coast that is not a specification to skim past. If you can see the water from your roof, corrosion class will outlast every other number on the datasheet in importance. More on the three phase picture in three phase homes and batteries.

Where it suits, and where it does not

It suits you if your roof is broken into several faces or has shade to work around, because four trackers is the most flexible single phase front end in this class. It suits you if you want a big array on a modest inverter. It suits you if you want whole home backup without buying a gateway box. It suits you if you already own solar worth keeping. And it suits you if you live near the beach and take corrosion seriously.

There is also the unglamorous argument, which is the one I would weigh most heavily if the systems were otherwise close: Sungrow is the largest inverter manufacturer in the world, has had an Australian office since 2012, and has an enormous installed base here. That means parts, firmware and warranty service are all easy to get, and if we are ever unreachable, almost any solar electrician in the country has already worked on one. For something bolted to your house for twenty years, that is worth real money.

It suits you less if you want to max out a 30 kilowatt three phase connection, because the largest home hybrid stops at 25. Less again if you want to mix a Sungrow battery with somebody else's inverter, because the batteries pair with Sungrow hybrids only, although the inverter will happily work with another brand's existing solar. And less if floor space is tight, since the SBH battery is floor standing with no wall mount option, which is covered in the Sungrow home battery review.

One last thing worth checking on any quote, whatever the brand: ask for the usable battery capacity rather than the nominal figure, ask which model of inverter by its full name, and ask what the backup rating is in amps. Those three answers tell you more about a system than the headline price does. If you want a hand reading a quote you have already been given, I wrote reading a battery quote for exactly that.

Common questions