Hi

I have a slolar panel system and need to be able to judge the amount of power going in to the batteries against the amount of power from the inverter. I have a charge control panel from the solar panels which reads in Amp Hrs,the a meter to measure the output from my inverter reads in Kw.

My problem is that the panels are 24 volts and the inverter output is 240 volts.

Can any one help me with a formula to compare the two values so I can check when the batteries are getting an overall boost or when they are going down.

Thanks a lot

 

For starters, an amp hour is different from a killiowatt in that time is involved. A watt is an amp times a volt. 3 volts times 20 amps is 60 watts. 300 volts times 20 amps is 6,000 watts, or 6 killowatts. If this flow continues across time, you get killowatt hours. 6 killowatts flowing for 20 minutes is 2 killowatt hours.

 

Assuming you have a system like PV panel - battery - inverter. What you need to look for is that energy in equals energy out, not power. Power is an instanteneous value - you could take hundreds of kW for a very brief time, yet consume just a little bit of energy.

Lets say your PV panel produced 1000Ah at 24V over some (any) length of time. Then the energy produced and stored in batteries is 24kWh. (without accounting for losses)
This has no realtion to the secondary voltage, or power (kW) that can be used in one instant on the 240V output.

If you need to know the energy you consumed you have to add all the power readings in kW say every second from the meter and then divide by 3600 to get a figure in kWh.

 

Amp Hrs is a measure of electron charge.
kW is power.
kWh is energy.

It your solar panel delivers 10A at 24V, that is 10A x 24V = 240 watts

If your inverter output is 1A at 240V, that is also 240 watts.

At 100% efficiency, the inverter is barely able to supply the load without draining the battery.