How to correctly measure the accumulated energy of a solar panel system?

[marexz]

I would like to make my own mini-solar panel system project and i have to measure every day the accumulated energy. How to do it correctly because as i understand then it's not correct to just measure the voltage, that gives inaccurate result of the energy the accumulator will give. And is there are special device for that? Of course except the classic multimeter Thank you!

 

[klystron]

Use a microprocessor to continuously measure both the voltage and the current.

 

[BradtheRad]

An amp-hour meter is the most correct way to measure the energy which the battery has received from a charger.

Also to measure how much energy the battery has put out to a load.

An amp-hour meter is different from the watt-hour meter which measures electrical power going to our houses. Both factor in the elapsed time.

 

[swethamenon]

Can we use rheostat as the load?/
then using sensors measure V&I..connect it to energy chip

 

[BradtheRad]

It is best if you introduce minimum resistance.

I built an amp-hour meter. For the current sense resistor I used several inches of wire.

The voltage across the wire was a few mV. I used an op amp to amplify the voltage. It took a great deal of adjusting to get zero output from the op amp when zero amps was going through the wire.

 

[swethamenon]

It is best if you introduce minimum resistance.

I built an amp-hour meter. For the current sense resistor I used several inches of wire.

The voltage across the wire was a few mV. I used an op amp to amplify the voltage. It took a great deal of adjusting to get zero output from the op amp when zero amps was going through the wire.

So if use rheostat and energy chip it makes errors??

I've a doubt too,is the energy chip ADE7751 can use for dc energy measuring?

 

[jeffrey samuel]

So if use rheostat and energy chip it makes errors??

I've a doubt too,is the energy chip ADE7751 can use for dc energy measuring?

I have to say power lost over the rheostat will be more significant and this loss has to be considered if your going to calculate the total power generated by the Solar panel

 

[swethamenon]

I have to say power lost over the rheostat will be more significant and this loss has to be considered if your going to calculate the total power generated by the Solar panel

But in the real scenario we have to use load which cause power loss right?
so by using only wires how can we say the energy of panel.
Do any one konw about ADE 7751..wil it work for dc input?

 

[BradtheRad]

Yes, you want to minimize the power loss.

That is why the sense resistance should have a very low ohm value. It should generate only a high enough volt reading to be measured by your device.

It is fine to use a rheostat (or potentiometer) as a sense resistor, to experiment until you find out what is a suitable ohm value.

Do any one konw about ADE 7751..wil it work for dc input?

The ADE 7751 datasheet describes it as being intended for AC monitoring.

I would imagine there is an energy metering chip meant to monitor DC.

 

[swethamenon]

Yes, you want to minimize the power loss.

That is why the sense resistance should have a very low ohm value. It should generate only a high enough volt reading to be measured by your device.

It is fine to use a rheostat (or potentiometer) as a sense resistor, to experiment until you find out what is a suitable ohm value.



The ADE 7751 datasheet describes it as being intended for AC monitoring.

I would imagine there is an energy metering chip meant to monitor DC.

Can u suggest me to read any books or links?

 

[BradtheRad]

I have not used an energy metering chip.

The internet has home power related websites which show projects for making an amp-hour meter.

I constructed my amp-hour meter to function in the following steps.

1) Sense wire
2) amplifier (op amp)
3) voltage to frequency converter
4) counter

The V-to-F converter was difficult to construct because it needs to have linear performance.

I made my own 3-digit counter, but I should have installed a manufactured type with several digits (available on Ebay).

The counter must be capable of being reset to zero. You would normally do this after you read how many amp-hours came from the PV panels during the day.

 

[swethamenon]

I have not used an energy metering chip.

The internet has home power related websites which show projects for making an amp-hour meter.

I constructed my amp-hour meter to function in the following steps.

1) Sense wire
2) amplifier (op amp)
3) voltage to frequency converter
4) counter

The V-to-F converter was difficult to construct because it needs to have linear performance.

I made my own 3-digit counter, but I should have installed a manufactured type with several digits (available on Ebay).

The counter must be capable of being reset to zero. You would normally do this after you read how many amp-hours came from the PV panels during the day.

How we decide the time(amp hours)?
In PV panels volt n I changes with intensity of rdtn..so?
What should be taken into account

 

[BradtheRad]

How we decide the time(amp hours)?

For small systems we would use milli-amp-hours.

Suppose your PV panel puts out 400 mA continuously, and it is in the sun for 10 hours.

In one day you can expect it to produce 4 amp-hours.

Your amp-hour meter should be rated to handle the maximum current your panel puts out. It should be able to count up to the maximum amp-hours you expect in one day.

In PV panels volt n I changes with intensity of rdtn..so?
What should be taken into account

You can have max V and small A.
Or max A and small V.
You must find a compromise if you want maximum watts.

Normally you will attach a load or battery. The panel will supply a certain number of amps at a certain voltage. Watts = V * I.

Some trial runs with various loads will tell you when you get maximum watts.

 

[Sunny55]

Hi, maybe you should make a data logger system to collect data since the energy generated is measured on a daily basis.
This will save time.

 

[swethamenon]

I'm going to measure V&I and they will feed to chip ADE7751.
This will out freq pulses wch is proportional to power.Using PIC it's counted and energy is measured.Planning to measure energy for 24hrs.Is it good?Or which time period is to bt chosen?Is there any constraint for this?

For small systems we would use milli-amp-hours.

Suppose your PV panel puts out 400 mA continuously, and it is in the sun for 10 hours.

In one day you can expect it to produce 4 amp-hours.

Your amp-hour meter should be rated to handle the maximum current your panel puts out. It should be able to count up to the maximum amp-hours you expect in one day.



You can have max V and small A.
Or max A and small V.
You must find a compromise if you want maximum watts.

Normally you will attach a load or battery. The panel will supply a certain number of amps at a certain voltage. Watts = V * I.

Some trial runs with various loads will tell you when you get maximum watts.

 

[BradtheRad]

I'm going to measure V&I and they will feed to chip ADE7751.
This will out freq pulses wch is proportional to power.Using PIC it's counted and energy is measured.Planning to measure energy for 24hrs.Is it good?Or which time period is to bt chosen?Is there any constraint for this?

Of course there is more than one way to measure energy output.

There is testing with various loads. Take readings of V versus I, because it is different with each load.
This is an important test. Notice that with no load, you will get zero A output, but you will get maximum V. Thus you will get zero power output.

There is the total watt-hours in a 24 hour period. On a sunny day. On a cloudy day. In a scenario with no grid power, this number is vital.

There is the graph of output each moment, over a 24 hour period. This will tell you if it is worth using a sun-tracking mechanism.

 

[swethamenon]

Of course there is more than one way to measure energy output.

There is testing with various loads. Take readings of V versus I, because it is different with each load.
This is an important test. Notice that with no load, you will get zero A output, but you will get maximum V. Thus you will get zero power output.

There is the total watt-hours in a 24 hour period. On a sunny day. On a cloudy day. In a scenario with no grid power, this number is vital.

There is the graph of output each moment, over a 24 hour period. This will tell you if it is worth using a sun-tracking mechanism.

Sorry..i didnt get you

 

[sri5496]

i did a similar project on mppt of a solar panel for which i need to measure v and i ....i used a very low value.this is the current measurement circuit that i used

 

[swethamenon]

i did a similar project on mppt of a solar panel for which i need to measure v and i ....i used a very low value.this is the current measurement circuit that i used

actually What all fundamental things have to know to design dc energymeter for solar PV?
what all matters should i go thru

 

[sri5496]

actually What all fundamental things have to know to design dc energymeter for solar PV?
what all matters should i go thru

as been told in the previous posts by others basic method is using ammeter,voltmeter..readings measuring them over certain intervals of time and taking the average..and calculate the power ...or if u want further more description or measuring of power ,go through smart meters ....hope u understood me...