Input Voltage Requirements

Is the under mentioned specs acceptable for Eskom grid? Inverter is single phase.

Max. DC Input Voltage (V) 600
MPPT Range (V) 80~550
Start-up Voltage (V) 80
Min. Feed-in Voltage(V) 120
Nominal DC Input Voltage (V) 360
Max. Input Current (A) 12.5
Max. Short Current (A) 15
Number of MPPTs 3
Number of Strings per MPPT 1

Nominal Output Voltage is 220/230V

@Newbie based on another question I saw you asking I would recommend you consult a reputable installer to help you design the system so that it will perform the way you expect it should.

If you are talking about the Goodwe 10KT you mentioned in the other thread just note that, that inverter is only a PV inverter, meaning if the Eskom grid goes off, the inverter will also switch off.

1 Like

Understood. What i need is an off grid or hybrid inverter. Correct?

There is a host of info here already, lots to read through though, so let’s see if we can summarize it quickly:

What do you want to achieve @Newbie?

Triggered!!!

Kidding aside. The problem with that term is that it was hijacked by the purveyors of cheaper options, and now it no longer means the same thing as it did a decade ago.

Loosely, there are three kinds of inverters.

  1. PV-inverters, sometimes called Grid-tied inverters. These have no batteries. Whatever sunlight comes in is converted into AC power and injected into the grid. It couples with the grid and monitors it for an outage. If the grid goes out, the inverter switches off.
  2. Battery inverters. Incoming sunlight charges the battery. The inverter runs from the battery. Some of them are inverter/chargers. They can also charge the battery from the grid.
  3. Hybrid inverters. This combines features of the previous two, so it can couple with the grid, it can “mix” power (solar, battery, and grid), etc.

Then the marketing people decided that if they stuff an off-grid inverter and a solar charger in a single box, then it can be called a hybrid because it can do two things. And from that day forward there is confusion…

So, as TTT asked. What is the goal? Do you need backup if there is a grid failure? Do you want to save money on the energy bill? Both?

:slight_smile:

Load shedding benefits TTT. Initially i thought of getting the Luxpower SNA5000/Growatt SPF 5000ES inverter with the Hubble 2.75KW battery (1C) and add on later (more Batteries and solar panels). i saw this GoodWe (very popular in Australia) on this website (good price too) and thought of getting it as the inverter capacity is 7kw. Thus i will not need another inverter in the future if i want to ‘go bigger’ for power. You advice will be much appreciated.

The Goodwe is a hybrid. The topology is very close to a PV-inverter, with the solar power boosted directly to the high voltage DC rail and then switched into the AC network, and a buck/boost stage for charging and discharging a battery. So it is quite literally a mix of the two.

It is a far better inverter than the Growatt/LuxPower.

Do check the manual though. As I recall, they do advise against running certain kinds of loads, such as washing machines. If you need something that can power everything and anything when the grid is down, a good old LF design like a Victron Multiplus/Quattro remains the most robust option.

What type of budget do you envisage?
±R80k
±R120k

Then, do you like to tinker, control your system with external software as you learn more and more? Tune it to your liking.
Or just “install it, it must work”?

Last question: Do you want Lego, expandability, or “just one size and it fits all”?

Your battery will be too small for the inverter. You would need much more.

If for instance you use only 2kW power constanly then that battery would last almost 1 hour.
If you only use 300W (1 fridge and a light) that battery might give you 6.5 hours.

For a more normal home using a 5 kW inverter I would suggest 10kWh battery. 5kWh if you are going to manage your power like a dictator.

Correct Louis. i am just looking at a few lights, router and Fridge and Freezer for now. If the load shedding is at 5 or 6 but its staggered (3 - 4 hours at different times of the day) even better. If its start reaching stage 8, then two batteries minimum.

Lower TTT. i dont really need to control the system although i think the GoodWe allows you to do that. The Luxpower/Growatt can be used with software like Raspberry if you want to. As far as i know, you can add more inverters and more batteries if required (with Hubble, i dont know if you can mix and match or use only the size the you have). This is why i wanted to go for the 7KW GoodWe but i dont know if its PV or Hybrid.

That is where it gets interesting i.e. the startup current when both come on at the same time during LS.

That determines the size of the inverter, which can handle the with no problem, whilst powering the lights, router, and other stuff.

The Goodwe sounds like a very good idea then … if others agree with me.
It is Hybrid.

1 Like

Mmmh hang on just a tad. I declared earlier that “yeah, that is a hybrid”, but the spec sheet says nothing about the battery voltage range. The MS series is perhaps a normal PV-inverter? It has been years since I’ve worked with Goodwe. They used to have a very good HF design with a battery inverter included in the box.

Sorry to give you the run around Plonkster. Herewith is the data sheet:

No worries… I just don’t want to make an embarrasing mistake and then you buy the wrong stuff. I saw that sheet already. It even mentions supporting Sunspec… which really really sounds like a PV-inverter. There is no mention of the DC voltage range. I suspect this is a PV-inverter.

PV-inverters tend to be a tad cheaper than battery inverters too.

That was my thinking also (cheaper because its PV).

Please keep in mind that you might not be able to split circuits as easily as that. Inevitably this means that you will sit with more loads on the inverter than you planned, and if you underspec, you will be frustrated.