I've seen a few comments in unrelated posts and it's forming a question but I'm not sure how to ask it.

It's something around - "having the inverter on and then the wife turns on the hairdryer" or someone was asking about using a welder and an inverter. 
So I'm wondering, are there going to be limitations, or is this because of the type of limitations their inverters have...

So if I get a grid-tie hybrid inverter and there are many hairdryers on and there is power from eskom, will my inverter be ok? 

If I turn my power tools on, table saw etc, and there is power from eskom, life goes on? 

If there is no power from eskom and it's not a sunsynk, and there is sun and good things, I get power from the panels, but I need to be wary of the grid and not turn on table saws etc. If I do - what will I damage? Will it just trip the inverter and then I have a better sense of my limits?

 

25 minutes ago, MKRandburg said:

I've seen a few comments in unrelated posts and it's forming a question but I'm not sure how to ask it.

It's something around - "having the inverter on and then the wife turns on the hairdryer" or someone was asking about using a welder and an inverter. 
So I'm wondering, are there going to be limitations, or is this because of the type of limitations their inverters have...

So if I get a grid-tie hybrid inverter and there are many hairdryers on and there is power from eskom, will my inverter be ok? 

If I turn my power tools on, table saw etc, and there is power from eskom, life goes on? 

If there is no power from eskom and it's not a sunsynk, and there is sun and good things, I get power from the panels, but I need to be wary of the grid and not turn on table saws etc. If I do - what will I damage? Will it just trip the inverter and then I have a better sense of my limits?

 

Let me try. If all those hair dryers are on non essentials with power nothing can ever happen to the hybrid. The power for loads do not pass through the inverter. The inverter just adds what it can towards the load. The rest comes from the grid.

If they are on the essential side all OK provided you are below the inverter output. Here again it's not that simple. A Sunsynk has a paas through higher than its rating. Some other makes sold as hybrid but in fact off grid units might pop before their thermal tripping device operates when you start that saw. Here all the power weather from PV battery or grid passes through the inverter. Running at 100% capacity or even if it operates right with the saw if you are going to start that saw more than 6 times an hour you risk the motor overheating as well as your inverter. This is a save factor used through many years. It has to do with the heating effect of starting current on the windings.

My 2c.

Mostly it is just the total load that matters.

But dimmers and half-wave clipped loads (like a hairdryer on 'cool' setting) are extremely harsh loads, and some inverters may bork at lower peak loads.

 

Ok, this helps kinda... 

So am I right in thinking... that if I put x watts on essentials (fridges, security etc) - and calculate that that power draw is say 80% of my inverter rating (I hope I've used the right terminology here). And the rest on non essentials - hairdryers and table saws, I won't damage my inverter? But if the grid goes down - and there is enough sun I can only use whatever is coming from the inverter, i.e I can only use my essentials.  

 

2 minutes ago, JustinSchoeman said:

Mostly it is just the total load that matters.

But dimmers and half-wave clipped loads (like a hairdryer on 'cool' setting) are extremely harsh loads, and some inverters may bork at lower peak loads.

 

I almost understand this but not quite... is the bottom line be careful what you put on your essential side? 

1 minute ago, MKRandburg said:

I almost understand this but not quite... is the bottom line be careful what you put on your essential side? 

Wait, I'm not ready for bottom lines yet. I still need to understand.

 

22 minutes ago, MKRandburg said:

Ok, this helps kinda... 

So am I right in thinking... that if I put x watts on essentials (fridges, security etc) - and calculate that that power draw is say 80% of my inverter rating (I hope I've used the right terminology here). And the rest on non essentials - hairdryers and table saws, I won't damage my inverter? But if the grid goes down - and there is enough sun I can only use whatever is coming from the inverter, i.e I can only use my essentials.  

 

This is about right. I have to mention not all hairdryers have the clipping problem. The most common way of getting the mid heat on a hairdryer is using a diode to limit the heat to 50%. When only the fan is on then its just like a normal table/pedestal fan. BUT THE Key - if on non essentials no matter if the unit clips in any format there will be no harm to the inverter.

I am using dimmer technology on small 750W, 1500W @ 12V and hair dryer at full/med/fan only on a 2.4kW and no problem for the inverters at all. Yes the power factor is affected but not the massive problem it is normally made to be.

When having fridges on essential remember the about 6 times normal power needed when a fridge does start. This excludes new high tech A++ fridges. So this means you cannot use the running power of fridges and run the inverter at 80%. Unless a long outing normal LS fridges can stand for 2.5hrs without being on the inverter. Or one can put the main fridge on inverter and leave the other fridges/deep freezers off. Why I say this some normal households do have 6 or more fridges. They will just discharge the battery too fast on a load that is not really needed to be powered 100% of the time.

Edited September 9, 20224 yr by Scorp007

@MKRandburgi see you still at it 😂😂😂 Actually I think you are going about this in a very smart way & a lot of ppl will learn from the way you are trying to build your system. 

I will answer your questions based on the conversation we had the other day on the Voltronics High voltage batteryless capable inverter. Let's say you have insufficient Solar to power the entire load, all that happens when the grid is present is that it will blend power sources but will provide maximum of the PV it can. So load = 5Kw & PV = 3kW then the shortfall will be 2kW from the Grid. In this scenario no battery available because you running batteryless. 

Now it starts to loadshed. The inverter will trip. It will not get damaged but it's output will stop. It's stops because you are demanding more than what the PV solar availability is at its disposal. 

What you would have to do to have the inverter restart without tripping is restart but switch off the major high loads. Then she will continue happily at a sub 3kW load. This is very tricky on a cloudy day. However, if you accept this limitation & reduce your load to minimal that is needed you will be okay. Minimal needed might be the fridge, freezer & the WiFi router. Remember this is a cloudy over cast day. 

On a sunny day you will not experience this problem. A battery is a good addition to this inverter. However, the way you want to operate this machine is nothing wrong, you must just understand the limitations that go with it. 

What is described here is the High Voltage Solar Charge controller Batteryless operation of the Voltronics machine. 

I ran my own inverter like this for the better part of 6 months & she is still alive & kicking very well. 

 

Thanks @Steve87 I find the topic very interesting and I'm trying to understand more. 

11 hours ago, Steve87 said:

Now it starts to loadshed. The inverter will trip. It will not get damaged but it's output will stop. It's stops because you are demanding more than what the PV solar availability is at its disposal. 

So this I understand and I guess the other issues people are talking about are what @Scorp007 is referring to here: 

18 hours ago, Scorp007 said:

Some other makes sold as hybrid but in fact off grid units might pop before their thermal tripping device operates when you start that saw. Here all the power weather from PV battery or grid passes through the inverter.

So it very much depends on the kind of inverter you have. 

13 hours ago, Steve87 said:

What is described here is the High Voltage Solar Charge controller Batteryless operation of the Voltronics machine. 

So if I was to try and understand splitting the db into essentials and non essentials - you would do this so as to not have certain types of power going through the inverter when there is no power coming from the gird? 

And I guess you would do it for convenience - so when it trips, you don't have to run around the house switching things off, or I guess it could work seamlessly and just automatically switch over to batteries, and then you make sure that, what is on the essentials side will only draw enough power for which the batteries can cope with, so you don't end up using up the batteries in an hour. Or tripping the system or destroying your batteries, if they haven't been protected/wired up appropriately. Am I getting it? 

I guess the rules of the system change when you're trying to do things without batteries. 

13 hours ago, Steve87 said:

What you would have to do to have the inverter restart without tripping is restart but switch off the major high loads. Then she will continue happily at a sub 3kW load. This is very tricky on a cloudy day. However, if you accept this limitation & reduce your load to minimal that is needed you will be okay. Minimal needed might be the fridge, freezer & the WiFi router. Remember this is a cloudy over cast day.

And if there were batteries in this scenario - the inverter would just blend the power from the batteries and the PV.

But in our situation on a cloudy day like this, if it kept tripping, we'd flip our change over switch to generator and operate as we do now (without solar). 

Would repeatedly tripping the inverter cause damage? 

And I'm right in saying that a Sunsynk wouldn't offer me this functionality? It would need a battery because it stops working when there is no alternative source to blend with solar? Or is it a different reason? 

 

 

And I'm right in saying that a Sunsynk wouldn't offer me this functionality? It would need a battery because it stops working when there is no alternative source to blend with solar? Or is it a different reason? 

Yes partly. The Sunsynk works best with a battery. You can however set to start the genny without a transfer switch if you have no grid. You can also select how much power to use from the genny as to keep it in a stable zone. This can be via an automatic transfer switch and with the Sunsynk you can also set the time. During this time one can charge the battery to limit run time.