DIY OG Solar install

[Speedster]

I will give you an example.
Washing machine on
Kettle on
Air Fryer on
Microwave on
More than 5kW usage.

This did not trip the inverter, because Esdom was still available. Esdom did supplement the rest of the power that was over my 5kW inverter.
But if Esdom was not available it would trip the inverter. (5kW inverter)

Not all inverters have this pass-through functionality. It's important to know the limits and capacity of your own device.

 

[itareanlnotani]

I will give you an example.
Washing machine on
Kettle on
Air Fryer on
Microwave on
More than 5kW usage.

This did not trip the inverter, because Esdom was still available. Esdom did supplement the rest of the power that was over my 5kW inverter.
But if Esdom was not available it would trip the inverter. (5kW inverter)

Most decent ones will also have surge rating where they can provide more than rated power for a shortish period, so the **occasional** overage is ok (on those).


My 3kw Victron for example can push to about 5kw temporarily. Not something you want to do to an inverter though, as lifetime shortens, heat etc.
Does cater for a few minutes though, which is enough for the unit to go into overdrive and you can tell significant other to maybe turn something off as the inverter will shut off otherwise.

 

[lexity]

I will give you an example.
Washing machine on
Kettle on
Air Fryer on
Microwave on
More than 5kW usage.

This did not trip the inverter, because Esdom was still available. Esdom did supplement the rest of the power that was over my 5kW inverter.
But if Esdom was not available it would trip the inverter. (5kW inverter)

Question for you...

All those devices are rated in Watts per hour, right?

If that's true, then at which point do you go over 5kw?

For example, if the washing machine uses 2200w in an hour, then it has only used roughly half of that 30 minutes in.

Same with the others... for instance, kettle you are not using for a full hour.

If the vacuum cleaner, even tho it's not on your list, is 800w, then after twenty minutes cleaning, you will only have used one third of 800 wats i.e. 266.

 

[soulie]

Question for you...

All those devices are rated in Watts per hour, right?

If that's true, then at which point do you go over 5kw?

For example, if the washing machine uses 2200w in an hour, then it has only used roughly half of that 30 minutes in.

Same with the others... for instance, kettle you are not using for a full hour.

If the vacuum cleaner, even tho it's not on your list, is 800w, then after twenty minutes cleaning, you will only have used one third of 800 wats i.e. 266.

its demand side rated ,not as per meter rated ,load irrespective of time .thats why if you are running say compressors or pumps you cant work on the run current but only on the locked rotor current ,as that spike will determine whether it runs or doesnt .

 

[lexity]

its demand side rated ,not as per meter rated ,load irrespective of time .thats why if you are running say compressors or pumps you cant work on the run current but only on the locked rotor current ,as that spike will determine whether it runs or doesnt .

Doesn't make sense to me.

It can't be using its rated wattage every second. Surely not.

I must be missing something else.

 

[soulie]

Doesn't make sense to me.

It can't be using its rated wattage every second. Surely not.

I must be missing something else.

youre overthinking again ,the load doesnt change over time ,the meter does .so if you have a 12 amp motor on a 15 amp inverter it wont start because the initial inrush is say 18 amps unless the inverter has an overcurrent allowance .

 

[soulie]

load is a constant ,unless your voltage changes ,so a 1000 watt load will draw 1000 watts ,over an hour your meter will turn once ,in 30 minutes it will turn 1/2 a turn.so if you run your kettle for an hour it will be 3000 watts for an hour ,if you run it for 3 minutes it will be 3000 watts for 3 minutes .

 

[Speedster]

Question for you...

All those devices are rated in Watts per hour, right?

If that's true, then at which point do you go over 5kw?

For example, if the washing machine uses 2200w in an hour, then it has only used roughly half of that 30 minutes in.

Same with the others... for instance, kettle you are not using for a full hour.

If the vacuum cleaner, even tho it's not on your list, is 800w, then after twenty minutes cleaning, you will only have used one third of 800 wats i.e. 266.

What are watts and watt-hours?

With many forumites being forced to embrace electrical backup and solar systems I thought it might be helpful to put together a little explainer on the basic theory regarding energy and power (and maybe save some of my sanity in the process). The idea isn't to be an electrical course (wayyy...

mybroadband.co.za

 

[leon.davibe]

I will give you an example.
Washing machine on
Kettle on
Air Fryer on
Microwave on
More than 5kW usage.

This did not trip the inverter, because Esdom was still available. Esdom did supplement the rest of the power that was over my 5kW inverter.
But if Esdom was not available it would trip the inverter. (5kW inverter)

Yea inverter dependant
Exceeding max

The cheaper axperts/off grid inverters will switch over to eskom in bypass mode if eskom is present solar won't be used and relegated to charging the battery

The sunsynk/deye can blend eskom so will still use solar and supplement from eskom

But yea if Eskom is gone and you exceed the inverter max will see it trip overload

 

[leon.davibe]

Doesn't make sense to me.

It can't be using its rated wattage every second. Surely not.

I must be missing something else.

All devices are rated in watts

ie kettle uses 2000w so it will be pulling 2kw all the time

Our electricity is measured in kwh
so drawing 1kw for an hour long
So leaving the kettle on for an hour will consume 2x kwh units

The same for battery
ie the battery is 2.5kwh

So you can leave the kettle on if no losses for 1hr 15min

You are conflating peak draw and energy stored

 

[leon.davibe]

Most decent ones will also have surge rating where they can provide more than rated power for a shortish period, so the **occasional** overage is ok (on those).


My 3kw Victron for example can push to about 5kw temporarily. Not something you want to do to an inverter though, as lifetime shortens, heat etc.
Does cater for a few minutes though, which is enough for the unit to go into overdrive and you can tell significant other to maybe turn something off as the inverter will shut off otherwise.

yea most will (rule of thumb) allow double the output for milliseconds for startup surge from induction devices
and can do smaller overload for longer ie it may allow 10% overload for 30s - 1min model dependant\

i have seen almost 5500w on my kodak 5kw for short period testing which stove plates i can run in combo

 

[soulie]

It can't be using its rated wattage every second. Surely not.

yip it is .

 

[leon.davibe]

Not all inverters have this pass-through functionality. It's important to know the limits and capacity of your own device.

it is also a setting that can be enabled or disabled

if disabled the inverter will trip when overloaded even if eskom is present
even the cheapies ie axperts have this feature

not the same thing as the passthrough / blending the more expensive sunsynk/deye/victron
you get hybrid axperts that can blend too
but unfortunately the term hybrid is thrown around willy nilly with inverters that can charge hybrid solar and eskom , but aren't hybrid in what the term was meant for

 

[leon.davibe]

Question for you...

All those devices are rated in Watts per hour, right?

If that's true, then at which point do you go over 5kw?

For example, if the washing machine uses 2200w in an hour, then it has only used roughly half of that 30 minutes in.

Same with the others... for instance, kettle you are not using for a full hour.

If the vacuum cleaner, even tho it's not on your list, is 800w, then after twenty minutes cleaning, you will only have used one third of 800 wats i.e. 266.

they are rated in peak watt , now yes a kettle will always use its rated watt
other devices not so much ie tv the brightness and other factors play a role
like a pc gpu is rated 200w but will idle at 20w if only browsing not playing a game
and use less power if playing less demanding titles especially if vsync is on

the moment the wattage of all devices is 5000 sustained the inverter will trip bar overload functionality naturally

the washing machine will use 2200w and consume 2200wh in an hour
2.2KW for an hour ie 2.2kwh

if you run the washing machine for 30 min it will still consume 2200w but only use 1100wh or 1.1kwh from battery or eskom

but yea washing machines doesn't actually use that much it may be the start-up wattage rating or if it has some form of heating function that it will draw that much constantly , can turn the heating function off while running it from battery

 

[lexity]

yip it is .

Can't be.

The rating is what it uses over an hour of transfer.

So it's not 'using 2kw every second' or 'all the time'. It's pulling 2kwh all the time.

It's using/pulling 2000/3600 every second. A little over half a watt. Even I know that. It's a rate of transfer. And all rates of transfer are 'respective of time'.

So my layman's way of putting it is that 'peak draw' is obviously referring to a physical limit (some kind of breaker) that is measured in amps, but responds to heat prior to the effect that an unacceptable predicted load being transferred at any instant in time will have. Traditionally it is heat melting a thinner or lower-gauge wire.

 

[soulie]

Can't be.

The rating is what it uses over an hour of transfer.

So it's not 'using 2kw every second' or 'all the time'. It's pulling 2kwh all the time.

It's using/pulling 2000/3600 every second. A little over half a watt. Even I know that. It's a rate of transfer. And all rates of transfer are 'respective of time'.

So my layman's way of putting it is that 'peak draw' is obviously referring to a physical limit (some kind of breaker) that is measured in amps, but responds to heat prior to the effect that an unacceptable predicted load being transferred at any instant in time will have. Traditionally it is heat melting a thinner or lower-gauge wire.

my goodness .....slow down and go read what has been posted on this page .

 

[soulie]

heres a rating plate ,this motor will draw 2.2 kw from the second you turn it on untill infinity ,except on startup where it will draw up to 80% more .a 5kw inverter will only just start this under load ,so we add a current limiter for startup or a soft start unit to limit the inrush current .

 

[leon.davibe]

Can't be.

The rating is what it uses over an hour of transfer.

So it's not 'using 2kw every second' or 'all the time'. It's pulling 2kwh all the time.

It's using/pulling 2000/3600 every second. A little over half a watt. Even I know that. It's a rate of transfer. And all rates of transfer are 'respective of time'.

So my layman's way of putting it is that 'peak draw' is obviously referring to a physical limit (some kind of breaker) that is measured in amps, but responds to heat prior to the effect that an unacceptable predicted load being transferred at any instant in time will have. Traditionally it is heat melting a thinner or lower-gauge wire.

edit: normally the rating is for peak load
you do get some devices that quote other metrics ie yearly usage etc to give people an idea of efficiency savings vs other similar devices



it is using 2kw all the time if you used it for an hour runtime then it used 2kwh
if you used it for 30min then it would pull 2kw load and consume 1kwh for the 30 min runtime
and likewise if you run it for 2 hrs then it would pull 2kw and consume 4kwh for the 2 hrs of runtime

 

[soulie]

edit: normally the rating is for peak load
you do get some devices that quote other metrics ie yearly usage etc to give people an idea of efficiency savings vs other similar devices



it is using 2kw all the time if you used it for an hour runtime then it used 2kwh
if you used it for 30min then it would pull 2kw load and consume 1kwh for the 30 min runtime
and likewise if you run it for 2 hrs then it would pull 2kw and consume 4kwh for the 2 hrs of runtime

imagine if we were billed per kwminute

 

[lexity]

load is a constant ,unless your voltage changes ,so a 1000 watt load will draw 1000 watts ,over an hour your meter will turn once ,in 30 minutes it will turn 1/2 a turn.so if you run your kettle for an hour it will be 3000 watts for an hour ,if you run it for 3 minutes it will be 3000 watts for 3 minutes .

There is no way any person alive on this planet will use 3000w running his 3000w kettle for 3 minutes.

Not sure where you bought your license.

Probably a government rubber-stamp, where you don't have to watch what you say.