If I had a 2000watt resistive PWM DUMP load, and the average pwm signal (10 minutes) was over 50%, would that not indicate that I have approx 1000watts of available PV power that I should use for and opportunity load?
At 50% duty cycle, a 2000W load should be dissipating 1000 watts *IF* the voltage you are applying to that load is at the voltage required to dissipate 2kW in that resistor.
I'd also use a fan. Maybe.
Where am I going here is as follows:
An opportunity load would be engaged based on the PWM% (last 10 min avg) indicating that excess PV power is available.
That load would stay engaged during a minimum run timer MRT (say 20min) .
When MRT =0 then if PWM%avg >0% and SOC >90% the load would continue for 5minutes and rechecked.
If the PWM%avg <0% or SOC< 90% the load would disengage.
A delayed restart timer DRST (5min) would prevent premature re-engagement.
The system would recheck PWM%avg and SOC every 5minutes for possible re-engagement.
This approach would work even without an actual PWM load.
My planned DUMP LOAD would be a rewired hot water heater run my primary inverter. shown below.
I bypass the pv input around the controller to the resistance heater load. An SSR or DC contactor can be used to switch the PV input. I use a contactor now with it just being on off controlled by Aux . But I guess it could be pwm using a ssr or igbt depending on pv voltage.
Larry
Quote from: ClassicCrazy on May 07, 2024, 03:45:05 PMI bypass the pv input around the controller to the resistance heater load. An SSR or DC contactor can be used to switch the PV input. I use a contactor now with it just being on off controlled by Aux . But I guess it could be pwm using a ssr or igbt depending on pv voltage.
Larry
Thanks for your input. I hate to correct myself twice in the same week but I found an error in the schematic. corrected one below.
My primary Aims 6000w inverter runs continuously for my water pump and fridge and other little stuff I can manually switch from grid. There is room for it to handle another 2kw.
Therefore I chose to use that 220v to run the DUMP. As the DUMP LOAD requires approx 10a @220 it enabled me to use 14-2 wire to that load with a 15a breaker.
How do you trigger opportunity loads?
regards Barry
The Aux contacts on the Classic have lots of different ways to turn on or off or pwm based on voltage, soc, etc . That is what I have been using.
I have a video on how I used the PWM of Waste Not to send extra power to water heater.
But switching the load using PWM might be difficult for the inverter depending - on mine it would make my LED lights flicker though didn't have effect on other loads.
https://youtu.be/s7trVpHLts4?si=gOzi8TAL_mV9fwJO
Larry
Quote from: Barry Fields on May 06, 2024, 07:26:43 PMWhere am I going here is as follows:
An opportunity load would be engaged based on the PWM% (last 10 min avg) indicating that excess PV power is available.
That load would stay engaged during a minimum run timer MRT (say 20min) .
When MRT =0 then if PWM%avg >0% and SOC >90% the load would continue for 5minutes and rechecked.
If the PWM%avg <0% or SOC< 90% the load would disengage.
A delayed restart timer DRST (5min) would prevent premature re-engagement.
The system would recheck PWM%avg and SOC every 5minutes for possible re-engagement.
This approach would work even without an actual PWM load.
My planned DUMP LOAD would be a rewired hot water heater run my primary inverter. shown below.
On disengagement, For lead acid batterys it is necessary to ensure that they be fully charged at least every 3days. There should be a flag for that being true. And a modification to the line above to this
If the PWM%avg <0% or SOC< 90%
or flag=false the load would disengage.
Attached is my implementation plan.
I've noticed led lights flicker when my Outback inverter use or drops utilitypower...and when the freezer kicks on. Large loads and power transfer. Must be ignored or it will drive you crazy!
Not all inverters are created equal.
I use two AIMS 6000w 48v inverters (Sigineer equivalent) 220v split phase
They are rated for overload as follows:
110%< load >125% 14 minutes 125%< load >150% 1 minutes 150%< load >300% 20 seconds
It is also important to load balance the 110v legs. If you have too much on one 110v leg, you can easily excede the limits on one leg.
While we are talking about load balancing, has anyone used or had experience with a 220v to 110v step down unit?
example
https://www.amazon.com/YaeCCC-Voltage-Transformer-Converter-Regulator/dp/B07T136SDV/ref=sr_1_12_sspa?crid=2A7N1L799NBT4&dib=eyJ2IjoiMSJ9.o7hEAG_elFSqUvfQns6-f_JrFPE5lDtm8SEkSHuoKoutCN5qbrbj2y5xUGqG45a_x_Iw7zO5Y7hQtmxFVMvi6msOwBbAv5F1FblNoJSG-yn4YJ0dc1DTSQlxZfndT-9-_wJtuz1JqQjRcG1l7hiojNIqXOAW9B90VQmBJyCN1XVTxFwSqlsrsH_Aquxw1eI_4Ld7vVbQkO9vsmwzAGOdsI7el7fUfeOZ_gjcVyizd8E.Icq8_iqxBwZJSwNc6byyd6Q8l58pbh78P2InOVp2alc&dib_tag=se&keywords=220v+to+110v+converter+step+down+3000w&qid=1716078831&sprefix=220v+to+110v+converter+step+down+3000w%2Caps%2C159&sr=8-12-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&psc=1
Quote from: Barry Fields on May 18, 2024, 08:39:36 PMWhile we are talking about load balancing, has anyone used or had experience with a 220v to 110v step down unit?
example
https://www.amazon.com/YaeCCC-Voltage-Transformer-Converter-Regulator/dp/B07T136SDV/ref=sr_1_12_sspa?crid=2A7N1L799NBT4&dib=eyJ2IjoiMSJ9.o7hEAG_elFSqUvfQns6-f_JrFPE5lDtm8SEkSHuoKoutCN5qbrbj2y5xUGqG45a_x_Iw7zO5Y7hQtmxFVMvi6msOwBbAv5F1FblNoJSG-yn4YJ0dc1DTSQlxZfndT-9-_wJtuz1JqQjRcG1l7hiojNIqXOAW9B90VQmBJyCN1XVTxFwSqlsrsH_Aquxw1eI_4Ld7vVbQkO9vsmwzAGOdsI7el7fUfeOZ_gjcVyizd8E.Icq8_iqxBwZJSwNc6byyd6Q8l58pbh78P2InOVp2alc&dib_tag=se&keywords=220v+to+110v+converter+step+down+3000w&qid=1716078831&sprefix=220v+to+110v+converter+step+down+3000w%2Caps%2C159&sr=8-12-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&psc=1
I've never seen it before.
It's continuous 1200W and 3kW maximum. Only weighs 13.4 pounds.
What is in it and how does it work ?
3kW for 30 minutes sounds like it might be a real transformer in it.
Almost too cheap even for 1200W if it is a transformer.
Their advert pictures are kind of funny. The box is shown on the table where the man and woman are working, like in the kitchen but the box is not doing anything and the meter is at zero. But man and lady are sure happy !
boB
Quote from: boB on May 19, 2024, 02:17:28 AMBut man and lady are sure happy !
Probably not married> ;D
I am interested in balancing the load on my 220v inverter from my 110v fridge.
Quote from: boB on May 19, 2024, 02:17:28 AMQuote from: Barry Fields on May 18, 2024, 08:39:36 PMWhile we are talking about load balancing, has anyone used or had experience with a 220v to 110v step down unit?
I've never seen it before.
It's continuous 1200W and 3kW maximum. Only weighs 13.4 pounds.
What is in it and how does it work ?
3kW for 30 minutes sounds like it might be a real transformer in it.
Almost too cheap even for 1200W if it is a transformer.
Their advert pictures are kind of funny. The box is shown on the table where the man and woman are working, like in the kitchen but the box is not doing anything and the meter is at zero. But man and lady are sure happy !
boB
Ha ha Bob - he is picking up a chili pepper with two spoons like it has the cooties .
She is making one weird smoothy from spinach and milk !
Maybe this is the new era of AI generated advertisements
Create a photo of two people who are happy to be using their step down converter to make a meal - ha ha .
Larry