GoSolr vs Solar

[Dolby]

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

At the end of the day, we all understand each other

 

[Lupus]

Higher average cloud cover presumably.

Yup that is the reason

 

[Speedster]

At the end of the day, we all understand each other

If we all understood each other you wouldn't have been confused about your battery's capabilities.

 

[Dolby]

If we all understood each other you wouldn't have been confused about your battery's capabilities.

Ah.

I can actually work it out . I thought most could :/

 

[leon.davibe]

The concept of watt per hour doesn't exist / is hardly ever used. If it did, it would be a rate of acceleration. I guess one could say my solar pv production increases at 300w/h until noon and then decreases at the same rate thereafter. That would make sense.

In your example of consistent draw one could say 580Wh/h and, maths being maths, the h/h would cancel themselves out leaving 580W. Power is always indicated by watts. Energy is watt-hours.

You can't use a watt over time, the concept is undefined. You can only use a watt-hour over time.

You use 500watt constantly
You don't use watt-hours

ie you used 500w load for an hour or 250w load for two hours

Watt hours is an expression

the same with ah

now yes it just make it easier if we are all talking the same language

it is just a means of expressing the power used ie to be bale to have a standard "unit" to make billing easier/understandable

 

[Kosmik]

Yup that is the reason

And the stupid angle. On the side of a valley and early morning and evening has major drop offs.

 

[Mike Hoxbig]

You use 500watt constantly
You don't use watt-hours

ie you used 500w load for an hour or 250w load for two hours

Watt hours is an expression

the same with ah

now yes it just make it easier if we are all talking the same language

it is just a means of expressing the power used ie to be bale to have a standard "unit" to make billing easier/understandable

It's not an "expression" to talk the same language, it's 2 different concepts entirely. W is power and Wh is energy...

 

[Kosmik]

Ah.

I can actually work it out . I thought most could :/

What is the actual question @Dolby ? I know we spoke a bit and I suggested a second battery as you appeared to be "capping" out , ie: excess solar.

If I recall you were getting something like 1.3kwp out of your array which gave you quite a nice haul but it dropped because your battery got full.

The second battery would take your total capacity to 5kva if I recall. You might have to balance it a bit to ensure bms balancing but you'd get the full potential output of your array with it.

 

[leon.davibe]

It's not an "expression" to talk the same language, it's 2 different concepts entirely. W is power and Wh is energy...

Yes Watt hours is a calculation/ unit of measure of the energy you used over x time espressed as if you used it in an hour

The kettle boils while using 2000w for 5min
So how do you get to how much watt hours you used you convert it to the "norm" /"standard most utilities use to bill us"/ "unit" that eskom uses to bill us

A unit of energy is 1kwh what does that mean

You can use a constant load of 1kw for 1 hour

Or boil your kettle 6 times for 5 minutes at a time to consume that 1kwh

All energy we use is billed/expressed as if you would have used it over an hour

 

[Speedster]

You use 500watt constantly
You don't use watt-hours

ie you used 500w load for an hour or 250w load for two hours

Watt hours is an expression

the same with ah

now yes it just make it easier if we are all talking the same language

it is just a means of expressing the power used ie to be bale to have a standard "unit" to make billing easier/understandable

What point exactly are you differing with me on?

 

[Speedster]

Yes Watt hours is a calculation/ unit of measure of the energy you used over x time espressed as if you used it in an hour

The kettle boils while using 2000w for 5min
So how do you get to how much watt hours you used you convert it to the "norm" /"standard most utilities use to bill us"/ "unit" that eskom uses to bill us

A unit of energy is 1kwh what does that mean

You can use a constant load of 1kw for 1 hour

Or boil your kettle 6 times for 5 minutes at a time to consume that 1kwh

All energy we use is billed/expressed as if you would have used it over an hour

I disagree that it is expressed as if you used it in an hour.

It is simply watts x hours. If my pool pump used 5kwh there is absolutely zero implication that it happened in a single hour.

Watts x hours = W x h and since in maths you can leave out the multiplication operator as it is implied W x h = Wh.

 

[leon.davibe]

What point exactly are you differing with me on?

You say you can't use watt over time

And watt hours is exactly that

It is expressed as if you used it over an hour

ie if i use the geyser at 3000w over a 30min period

The wh i used is expressed as the avg watt i would have pulled if i used all that energy over a 1 hour period ie i used 1.5kwh

Watt hours isn't a tangible thing it is just a means of expression/ unit we all use to express the energy we used ie to talk the same language

 

[leon.davibe]

I disagree that it is expressed as if you used it in an hour.

It is simply watts x hours. If my pool pump used 5kwh there is absolutely zero implication that it happened in a single hour.

Watts x hours = W x h and since in maths you can leave out the multiplication operator as it is implied W x h = Wh.

All energy we used is expressed in a unit which is essentially what would the avg watt be if we worked on the energy used over a 1 hour period

 

[Mike Hoxbig]

Yes Watt hours is a calculation/ unit of measure of the energy you used over x time espressed as if you used it in an hour

The kettle boils while using 2000w for 5min
So how do you get to how much watt hours you used you convert it to the "norm" /"standard most utilities use to bill us"/ "unit" that eskom uses to bill us

A unit of energy is 1kwh what does that mean

You can use a constant load of 1kw for 1 hour

Or boil your kettle 6 times for 5 minutes at a time to consume that 1kwh

All energy we use is billed/expressed as if you would have used it over an hour

2000W over 5 minutes is 2000 x 0.08 Wh of energy used.

You are overcomplicating a simple concept. When you think of voltage, do you think about how many amperes are used over an ohm?

 

[Speedster]

You say you can't use watt over time

And watt hours is exactly that

It is expressed as if you used it over an hour

ie if i use the geyser at 3000w over a 30min period

The wh i used is expressed as the avg watt i would have pulled if i used all that energy over a 1 hour period ie i used 1.5kwh

Watt hours isn't a tangible thing it is just a means of expression/ unit we all use to express the energy we used ie to talk the same language

No. You clearly don't understand energy measurement. A watt hour is exactly equal to 3600 joules of energy. It is very tangible. It's not just a language, it is a scientific unit. Your argument is akin to saying a litre or metre isn't a tangible thing, it is just a means of expression we use. That would obviously be utter rubbish.

For example, my pool pump used 5kwh. That says absolutely nothing about an average use over an hour.

 

[leon.davibe]

I disagree that it is expressed as if you used it in an hour.

It is simply watts x hours. If my pool pump used 5kwh there is absolutely zero implication that it happened in a single hour.

Watts x hours = W x h and since in maths you can leave out the multiplication operator as it is implied W x h = Wh.

Agreed it could be a 1kw pump running 5hours

Or a 0.5kw pump running 10 hours

All calculations are worked to be what would the avg watt be if used over a 1 hr period

 

[Speedster]

Agreed it could be a 1kw pump running 5hours

Or a 0.5kw pump running 10 hours

All calculations are worked to be what would the avg watt be if used over a 1 hr period

No. All calculations are worked as to how much energy you used. As with anything mathematical you can divide it by a factor (time in this case) to give an average rate.

Your point is like saying all distance is given so that it can be worked out what the average speed would be if travelled in a one hour period. No, distance is given to indicate distance. I can obviously divide it by time to work out an average speed, but that is an entirely different matter to just saying what distance one travelled.

 

[leon.davibe]

No. You clearly don't understand energy measurement. A watt hour is exactly equal to 3600 joules of energy. It is very tangible. It's not just a language, it is a scientific unit. Your argument is akin to saying a litre or metre isn't a tangible thing, it is just a means of expression we use. That would obviously be utter rubbish.

For example, my pool pump used 5kwh. That says absolutely nothing about an average use over an hour.

You meter counts the joules you used and deducts whatever you used from a "unit" which is an expression ie how many hours could you have used 1kw

 

[leon.davibe]

2000W over 5 minutes is 2000 x 0.08 Wh of energy used.

You are overcomplicating a simple concept. When you think of voltage, do you think about how many amperes are used over an ohm?

Well technically 0.8333...

 

[Speedster]

You meter counts the joules you used and deducts whatever you used from a "unit" which is an expression ie how many hours could you have used 1kw

If you say so. I guess when driving to Cape Town my odometer counts kilometres travelled and deducts whatever I travelled from a "unit" which is an expression. I.e. how many hours could I have travelled 100km/h.