Overview question on generation and storage

Captain Slow IRL

Hi all, I was wondering if ye could help me with the following.

How is generated electricity measured? Is it just instantaneous wattage?

I know consumption is kWh (how many kilowatts used in an hour), but is this term applicable to the generating side as well. If someone is generating 250Watts continuously (24V, 10 amps) for 10 hours, what kind of energy would they have stored?

Thanks in advance!

TimeToShine

Generated electricity is measured in MW, or power generated.

Consumption is measured in kWh because it allows you to quantify how much energy you are using.

In other words, generators generate power which is joules per second, and consumption is measured in the amount of these joules per second that you use.

Bruthal

TimeToShine wrote: »

Generated electricity is measured in MW, or power generated.

Consumption is measured in kWh because it allows you to quantify how much energy you are using.

MW and kW are the same thing. MW is used due to scale. GW can also be used for even larger scale. A 3kw kettle is a 3000 watt kettle, or a 0.003 MW kettle, or a 0.000003 GW kettle.

Its like saying your garden is 0.03 km long. We say 30 meters instead. Or its 300,000 meters from a to b. We say its 300km.

A generators capacity to generate is measured in kva or MVA since the amount of useful watts it can power depends on the load power factor. The power in watts can be measured on the lines from generators as its used.

For the op, are you asking about a generator charging batteries or something?

For 24v 10 amps for 10 hours, we will take it as 2.4kwh's (forgetting about power factor possibilities, probably DC anyway)

So if it was batteries being charged, in theory they would have taken on 2.4kwh's of stored energy, or 100 amp hours for 24 volt batteries.

If we take the battery as being 70 percent efficient in charging cycles, then only 7/10ths of the generator output will be converted to stored energy in the battery.

For a view of generation on the grid, most electricity is used as its generated, and useful watts as well as reactive, wattless etc are all measured . Electric cars would be one example of storing energy as its generated. Another is tourlough hill generation station. They are 2 examples of converting the electricity to another form of stored energy, then converting back to electricity again.

Heating a hot water cylinder, or storage heaters, is also storing energy, but it won't be converted back to electricity.

Lead acid are more efficient than 70%. Mine are listed 85% and displaying 95% characteristics.

Lithium based batteries are very close to 100% efficient.

Also there's charge controller, inverter, temperature and wiring/installation losses to be factored.

Just for arguments sake:

250W @ the turbine: 3% wiring loss: 243W
Charge controller: 85% efficient (depends on state of charge really): 206W
Wiring losses to battery: negligible (if done correctly).

Lead Acid Battery charge efficiency 85%: 175W
or direct to load, Inverter efficiency 90%: 185W

Battery to inverter efficiency 90%: 157W
1.56kWh after 10 hours if the batteries are empty enough to accept the charge.

Bruthal

Sir Liamalot wrote: »

Lead acid are more efficient than 70%. Mine are listed 85% and displaying 95% characteristics.

Slightly pedantic there.

Bruthal

Sir Liamalot wrote: »

Just for arguments sake:

250W @ the turbine: 3% wiring loss: 243W
Charge controller: 85% efficient (depends on state of charge really): 206W
Wiring losses to battery: negligible (if done correctly).

Lead Acid Battery charge efficiency 85%: 175W
or direct to load, Inverter efficiency 90%: 185W

Battery to inverter efficiency 90%: 157W
1.56kWh after 10 hours if the batteries are empty enough to accept the charge.

The discharge part of the cycle should be included too. After all, we won't know what capacity the battery really has until it is discharged and the delivered watt hours measured. A battery won't deliver the same watt hours at max current delivery as it would at c/10 for example. It might get closer when new, but what about after 100 cycles....

Simply measuring the amp hours the battery took to fully charge, and comparing to the stated capacity, is not enough.

Yup