Hello, I got a electrician to install a diode on my DB that connected on my geyser. The Diode is suppose to reduce the KW the geyser puts out. So the geyser is 4kw with the Diode it must only put out 2KW. The weird thing is when I check my solar it does not use 2KW it uses full 4KW and in some days and most days it does that and some days it does work with only 2KW. Why does this happens? Is it something I am not clearly understand?

The diode's function is to block the flow of current in one direction. In an AC circuit this direction alternates 50 times per second. So your geyser alternates between using 4kW and 0kW, at a rate of 50 times per second, effectively halving the power usage. Your inverter might struggle to measure this, because it is only logging a data point once every couple of minutes.

5 hours ago, Gman007 said:

Hello, I got a electrician to install a diode on my DB that connected on my geyser. The Diode is suppose to reduce the KW the geyser puts out. So the geyser is 4kw with the Diode it must only put out 2KW. The weird thing is when I check my solar it does not use 2KW it uses full 4KW and in some days and most days it does that and some days it does work with only 2KW. Why does this happens? Is it something I am not clearly understand?

Although the average power as expected is 2Kw, there is still  an instantaneous power peak of  4Kw on every alternate half cycle. This makes things difficult for the inverter dc-ac converter . And if the inverter doesnt avergage out its measurement over time, then you will have metrics showing peak power at times. And  the inverter may be fast enough to detect surges on cycle by cycle basis,  so you may not benefit with the diode mod. Unfortunately replacing the 4k element with 2k is going too be the only real option in the long term.

EDIT : unless there are members that had experience definitive gains by using the diode. 

Edited June 28, 20232 yr by BritishRacingGreen

On 2023/06/28 at 11:40 AM, Gman007 said:

Hello, I got a electrician to install a diode on my DB that connected on my geyser. The Diode is suppose to reduce the KW the geyser puts out. So the geyser is 4kw with the Diode it must only put out 2KW. The weird thing is when I check my solar it does not use 2KW it uses full 4KW and in some days and most days it does that and some days it does work with only 2KW. Why does this happens? Is it something I am not clearly understand?

Is the geyser taking double as long to heat up as before diode?

Also, if the inverter is struggling to measure the power, I wonder if the municipality electricity meter is also thinking it is pulling 4kW, when in fact it is half that...this diode could be causing more trouble than it is worth.

Edited June 29, 20232 yr by HendrikBigChief

On 2023/06/28 at 5:28 PM, BritishRacingGreen said:

Although the average power as expected is 2Kw, there is still  an instantaneous power peak of  4Kw on every alternate half cycle. This makes things difficult for the inverter dc-ac converter . And if the inverter doesnt avergage out its measurement over time, then you will have metrics showing peak power at times. And  the inverter may be fast enough to detect surges on cycle by cycle basis,  so you may not benefit with the diode mod. Unfortunately replacing the 4k element with 2k is going too be the only real option in the long term.

EDIT : unless there are members that had experience definitive gains by using the diode. 

@Bernardf

The easy way to see this in action is on hair dryers where the low heat also goes through a single diode and full power directly from the supply. 

This diode method is the easy way on resistive elements to reduce the power to element by 50%.

@HendrikBigChief

Power is power so the meter will also just measure 2kw pulses (2kWh in 1 hour) as it only flows half of the time. 

Correction. @BritishRacingGreen

Has the right angle. Only clicked what was stated when driving home and a bit of time about the peak cycle value. 

Edited June 29, 20232 yr by Scorp007
Added the correction.

Thank you for everyones replies, that makes sense, just weird that the inverter on some days shows it incorrectly and then other days it works 100%

 

25 minutes ago, Scorp007 said:

@HendrikBigChief

Power is power so the meter will also just measure 2kw as it only flows half of the time. 

Will some electricity meters not also get confused in the same way the inverter gets confused?

The inverter incorrectly thought it was 4kw, maybe some electricity meters do the same?

1 hour ago, HendrikBigChief said:

Will some electricity meters not also get confused in the same way the inverter gets confused?

The inverter incorrectly thought it was 4kw, maybe some electricity meters do the same?

Inverters are low accuracy type of equipment. Any power meter or other measuring equipment have to pass a class 2 (0.2%) for accuracy. Consumers are thus protected that instrument will be accurate. These instruments all have calibration methods and are calibrated in a lab at the correct conditions. 

See the class shown on an old style meter.