Understanding a Sunsynk inverter

[Isetech]

Yes anyone can buy a Sunsynk inverter or battery, DIYer, green card holder or registered electrician. We all know that no matter how much everyone is trying to take control of this industry, nothing is going to change for a while yet.

Because technical support is international, it makes no difference where you buy the unit, price becomes the main factor.

If you buy the unit from Voltex (bit slow with their response to quote requests) or ARB (fast response and good prices), you will still use the same technical support. Just make sure they have stock before you do the bank transfer, this is a tricky situation.

It seems the stages of load shedding determine the stock and pricing, some will tell you it is the exchange rate

[Empowered]

Hi Isetech, hello and thanks for this informative thread.

This caught my attention and I'm wondering if you could explain more please...

As I mentioned earlier, a 550 watt panels with a max current 13 amps cannot be used with a 5kva Sunsynk inverter (11 amp), so you would have to get an 8 kva inverter or get smaller panels.

Someone mentioned this to me recently too. Why can't one use 550watt panels with a 5kva inverter?

[Isetech]

With the limited knowledge I have of solar design, I stick to the data sheets.

I have read of others using 550 watt panels.

When I do the install at my workshop, I might try it to see what happens.

Do you have any input to share ?

Living and leanring by the day, always open to suggestions or a bit of technical advice.

Hi Isetech, hello and thanks for this informative thread.I havent

This caught my attention and I'm wondering if you could explain more please...



Someone mentioned this to me recently too. Why can't one use 550watt panels with a 5kva inverter?

[Justloadit]

Its not the panel wattage size, it has o do with the current the panel can provide.
Only until recently, PV panels would produce a voltage and the current never exceeded 11Amps, these panels are now providing up to 16Amps.

The electronics in the inverter are rated at 11Amps, so the 16Amps exceeds the inverter rating.
When the inverter goes into a MPPT mode, it loads the panel until it reaches the knee of the panel wattage, in the rated case the string would not exceed 11A, however with the higher current panels, the inverter will receive 16A, in a short while this will destroy the boost electronics due to over current.

[GCE]

Hi Isetech, hello and thanks for this informative thread.

This caught my attention and I'm wondering if you could explain more please...



Someone mentioned this to me recently too. Why can't one use 550watt panels with a 5kva inverter?

Ratings on electrical equipment are there for a reason - The design of the electronics , heat dissipation etc. on the MPPT
Would be like taking an 11Amp contactor and running 13 Amps through it every day for an hour or two - It is going to fail prematurely which means your expected 5 year warranty will fall away as all that information is logged
The voltage on the MPPT is even more critical as edge of cloud effect can lift that voltage by 20% depending on time of day.

You would not buy a 1/2 ton bakkie to take a 750Kg load at red line on the motor between PE and Cape town as a courier service and expect the bakkie to give you the same life expectancy - Brakes will fail prematurely , motor will go through head gaskets , overheat on hills etc - You would expect problems , same thing with an MPPT that is been driven hard.

[Isetech]

Besides all the technical reasons, product warranty is the most important factor.

Even when installing the units, I stick to the suggested spacing etc.

[Justloadit]

Ratings on electrical equipment are there for a reason - The design of the electronics , heat dissipation etc. on the MPPT
Would be like taking an 11Amp contactor and running 13 Amps through it every day for an hour or two - It is going to fail prematurely which means your expected 5 year warranty will fall away as all that information is logged
The voltage on the MPPT is even more critical as edge of cloud effect can lift that voltage by 20% depending on time of day.

Since a PV panel is a current source, the only change in the voltage of the panel is due to the effect of temperature.
The open circuit voltage between say -5°C and 25° to 55°C can say as much as 5V up when cold to down when hot from the specification sheet which is done at 25°C
What changes is the amount of current the panel provides. It can vary fr0m 0.5A early in the morning say at 08H00 to FSD amps example 11A between 11H00 to 13H00during a sunny day. Provided the Azimut angle is correct and panels facing North in the southern hemmisphere, and that there are no shadows and the panel is clean and free from bird droppings. As clouds come over, the MPPT voltage remains the same, only the current changes.

[Empowered]

Hi Isetech, GCE and Justloadi - thanks for your insights - very helpful and gives me a proper understanding of the issue.

I'm a novice at solar - I've been getting quotes for a 5KW PV system and I've come across so many different perspectives from the various installers, this issue being one of them. Some have given quotes for 450 panels, others 550 and one told me you can't use the 550 on a 5kw, while another said it makes no difference.

I googled to find out and found this thread. It's great to have confirmation and understanding - thanks! It makes sense that more hardcore current would put strain on an inverter.

Makes me wonder if this is part of the reason there's such a wait for Sunsynk inverter returns and repairs. I've seen people mention this on Facebook - maybe it's because they need to assess why the inverters that are brought in have problems and this sort of thing could be something they look for if all that information is logged.

[Isetech]

I dont think it is the solar panels are causing all the problems, I have heard that it is more to do with overloaded relays.

People have this idea that you can connect a 5 kva and not split the essential and non essential, just load eveything onto the inverter.

There are ways to do it, however you would need to install devices to control the load, like a PLC or smart swtiches or an ECU.

Undersized cables, another issue, some people use 2.5 mm as the grid supply and the UPS for a 5 KVA inverter, then they slap a roof full of panels and suddenly you have pass through current going up to 30 amps. This also puts huge strain on the inverter.

This is why it is so important to have detailed documents about the sytem and why it is important to lock the settings and not let people make adjustments onece commsioned.

Makes me wonder if this is part of the reason there's such a wait for Sunsynk inverter returns and repairs. I've seen people mention this on Facebook - maybe it's because they need to assess why the inverters that are brought in have problems and this sort of thing could be something they look for if all that information is logged.

[Isetech]

If you are looking for solar panels for a 5 kva Sunsynk inverter, I would say the 460 watt JA panel would be the most suitable if you have the space on the roof.

If you dont have a large roof space, then scaling down and using smaller panels might be a better option because then you can double them up and maximize the avaialbe roof space.

I see some people mount the panels right to the end of the roof top bottom and sides, I hear it is not a smart idea, something to do with lightning and when it rains the wate rover shoots the gutter.