DIY OG Solar install

Fcon_Vpro said:
Geez you are stubborn.
Reading through these posts I picked up that you don't understand what power is and that you dont understand that different appliances have different power ratings based on how they function.

Power is an instantaneous measurement ie its the amount of work being applied at any instant or moment.
Power is not a measure over a period of time.

With electrical power, the power rating is dependant on the appliance type and what it does. Here are 3 examples.

A water heating element like a kettle or geyser will be a typical rating like 3kw or 4kw because its just a big resistor and doesnt do anything fancy. This tells us it can provide a constant 3kw for the duration its powered on. this helps us determine how quickly it can heat up a body of water from one temperature to another. You can lookup the formula for water heating.

An electrical motor has 2 ratings:
Start up and running watts
The power required to start up: there is a mass it needs to move from standstill and requires more power to get going, but once it's moving it requires less power to keep running. You need to know the start up power so that your power source is strong enough, and then you need the running power because it will help you determine how much energy it will consume over a period.
It's the equivalent of you pushing a car from standstill: difficult to get going but once it's moving its much easier to carry on pushing.

For the 3rd example let's use a typical washing machine. It has a water heating element, a motor to spin the drum, and electronics.
The washing machine only needs to provide the water heating element power rating because generally that's the biggest power requirement, and they don't need to tell us motor start up, etc because it's lower.

Power is how much work I can do at any given time.
Energy is how long can I maintain that power output for. It can be measured in joules, calories, watt hours.
The intellectual content is that 1kW hour is much easier to understand than 3600000 joules.
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Thanks for that reply but, since I'm so stubborn, did you look for the post that started this particular sequence of q&a's?

Do you know what started it off?
 
lexity said:
Thanks for that reply but, since I'm so stubborn, did you look for the post that started this particular sequence of q&a's?

Do you know what started it off?
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Please post the link to the post you are referring to.
 
lexity said:
Let me try to ask this a different way. How many joules of energy did you consume in that hour?
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I tried to keep it in watt no need to add an extra calculation but if you do it goes something like this

Ok lets do 1000w

So for every second it is on it will consume 1000joule thus 3 600 000 for the hour

Eskom sells us a unit which is 1000watt for an hour long which is this 3 600 000 joules of energy

If i run the item 30 minutes i consume 1 800 000 joules

ie 1000j x 60second x 30 minutes

So the item is consuming 1000j for ever second it runs

So talking joules or watt is kinda like 6 of the one or half dozen of the other

No need to calculate joules as eskom bills us in 1Kwh so we just calculate everything in watts and hours

1000w is in the moment the H for an hour

So if the item runs for one hour it uses one full unit of 1Kwh

If it runs 30min it uses 0.5kwh

Having units of joule would mean that our meters would have to show our balance in scientific x.xx 10^x or we would need one wide screen to show balance which would turn out more difficult i would think

And since we use a lot starting with a unit that represents a lot
Makes it easier
 
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leon.davibe said:
I tried to keep it in watt no need to add an extra calculation but if you do it goes something like this

Ok lets do 1000w

So for every second it is on it will consume 1000joule thus 3 600 000 for the hour

Eskom sells us a unit which is 1000watt for an hour long which is this 3 600 000 joules of energy

If i run the item 30 minutes i consume 1 800 000 joules

ie 1000j x 60second x 30 minutes

So the item is consuming 1000j for ever second it runs

So talking joules or watt is kinda like 6 of the one or half dozen of the other

No need to calculate joules as eskom bills us in 1Kwh so we just calculate everything in watts and hours

1000w is in the moment the H for an hour

So if the item runs for one hour it uses one full unit of 1Kwh

If it runs 30min it uses 0.5kwh
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Okay, so I was right... watts are consumed.

So, now moving back on topic. Let's say I have a 1C 5Kwh battery. And a 5kW inverter.

Imagine there are no other losses. And we start this thought experiment with a fully-charged battery.

And I have 4 devices that are 1kw devices. They're all plugged into a multi-socket extension and all I have to do is turn on the power at the wall socket.

If I were to aim to hit the limit, and trip the system, by maxing out the inverter. Could I do that within the 1st hour of running all those 4 1kw devices simultaneously?

My layman's guess would be no.

Correct, so far?
 
lexity said:
Okay, so I was right... watts are consumed.

So, now moving back on topic. Let's say I have a 1C 5Kwh battery. And a 5kW inverter.

Imagine there are no other losses. And we start this thought experiment with a fully-charged battery.

And I have 4 devices that are 1kw devices. They're all plugged into a multi-socket extension and all I have to do is turn on the power at the wall socket.

If I were to aim to hit the limit, and trip the system, by maxing out the inverter. Could I do that within the 1st hour of running all those 4 1kw devices simultaneously?

My layman's guess would be no.

Correct, so far?
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No. Guy, how flipping hard headed can one person be. Watt is a rate. You cannot consume a rate.

And to answer your question - drawing 4kw should never trip a 5kw inverter. At some stage the battery will run flat and then the system will power down. Battery is a store of energy and measured in kWh.
 
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lexity said:
Oh look, suddenly it makes perfect sense to measure consumption in watts

:laugh:
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how the dick do you get to consumption out of running watts ? without time, load etc ,if you run it for an hour it will be x if you run it for 1/2 hour it will be half of x .but the load stays the same ie 1000 watts per second ,per millisecond,per minute .
 
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Speedster said:
No. Guy, how filling hard headed can one person be. Watt is a rate. You cannot consume a rate.

And to answer your question - drawing 4kw should never trip a 5kw inverter. At some stage the battery will run flat and then the system will power down. Battery is a store of energy and measured in kWh.
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I try not to get fixated on the terminology/labeling.

Like with other things labels are not the important thing. Yes I understand you get used to them.

It's a bit like bitcoin. From the early days the analogue was the wallet and coins. A completely inept analogue, because what you have in your wallet are keys, not coins.

To master a topic you should be able to describe its concepts accurately using mostly - if not completely - nothing more than plain English. That and a good metaphor goes a heck of a long way.

If this is too much for you to tolerate, ok.... I get it.

Until then I'll keep on having a go at unpacking the terminology.

:cool:
 
soulie said:
how the dick do you get to consumption out of running watts ? without time, load etc ,if you run it for an hour it will be x if you run it for 1/2 hour it will be half of x .but the load stays the same ie 1000 watts per second ,per millisecond,per minute .
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Dude... please, fix that punctuation.
 
lexity said:
Okay, so I was right... watts are consumed.

So, now moving back on topic. Let's say I have a 1C 5Kwh battery. And a 5kW inverter.

Imagine there are no other losses. And we start this thought experiment with a fully-charged battery.

And I have 4 devices that are 1kw devices. They're all plugged into a multi-socket extension and all I have to do is turn on the power at the wall socket.

If I were to aim to hit the limit, and trip the system, by maxing out the inverter. Could I do that within the 1st hour of running all those 4 1kw devices simultaneously?

My layman's guess would be no.

Correct, so far?
Click to expand...
Conflating two things the peak and consumption

The inverter can carry 5kw load indefinitely as long as you have enough batteries

So lets say you have 5items of 1kw you power them on the inverter will not trip it can carry that load ,the battery is 1c so it can also supply the 5kw and not trip

The energy stored in the battery is 5000watt for an hour long

So if you run all 5 you can run for an hour before the battery is flat

(Perfect world no losses naturally)

If you run 1x 1kw item you can for 5hrs

So lets take a kettle you run a kettle of 2000w/2kw for 6min

You thus used 2kw for 10% of an hour

If you ran it for a full hour you would consume 2kwh note the H,
And 10% of an hour would mean 0.2kwh consumed

So you have to calculate the items that don't run constantly by getting the percentage of an hours * by its load (converted to kw) to calculate kwh used

I keep giving examples because because we tend to see what we want to see and examples whacks us out out of it at some point
 
The hour part 1000w for an hour is 1000watt hour

If you run it for 30min you consumed 500watt hours

ie running a lower watt item lets say a tv 100w, u would need to run it for ten hours to be equal to a 1000watt item running for an hour

focus on the HOUR of kwH
 
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