using excess power to heat water (For Dummies)

[kauaisolarman]

no still trying to figure all that good stuff out.

its hard for me because i am setting up more than 1 system so 1 system will most likely have 2 controllers in follow me and the other is a single controller.

just want to find out exactly how to harvest that "wasted power" which both systems will have.  thats why the multitude of questions. 

really want both systems (single and dual CC) to be able to harvest wasted power and use WBjr as it seems to be the best route for best battery charge, but i am torn as i understand WBjr can only be on AUX 2 which i need for PWM use to control the SSR for harvesting that wasted power during absorb and float mode.


exact how do i set the start and end parameters using a SSR on AUX 1 and WBjr on Aux 2?  I read that with WBjr (on AUX 2) you can setup AUX 1 SSR to turn on when a certain SOC% is reached and turn off when another lower SOC% is reached all based on the more accurate SOC% that WBjr gives you.  Just can't find anywhere that tells you how to set this up.  can anyone help or point me in the right direction to make this happen? 

this seems to be another viable option  for harvesting wasted power vs the PWM aux 2 method

[SolarMusher]

no still trying to figure all that good stuff out.

its hard for me because i am setting up more than 1 system so 1 system will most likely have 2 controllers in follow me and the other is a single controller.

just want to find out exactly how to harvest that "wasted power" which both systems will have.  thats why the multitude of questions. 

really want both systems (single and dual CC) to be able to harvest wasted power and use WBjr as it seems to be the best route for best battery charge, but i am torn as i understand WBjr can only be on AUX 2 which i need for PWM use to control the SSR for harvesting that wasted power during absorb and float mode.


exact how do i set the start and end parameters using a SSR on AUX 1 and WBjr on Aux 2?  I read that with WBjr (on AUX 2) you can setup AUX 1 SSR to turn on when a certain SOC% is reached and turn off when another lower SOC% is reached all based on the more accurate SOC% that WBjr gives you.  Just can't find anywhere that tells you how to set this up.  can anyone help or point me in the right direction to make this happen? 

this seems to be another viable option  for harvesting wasted power vs the PWM aux 2 method

You'd better use Aux1 waste not rather than SOC% for this WH, about the same as waste not aux2 but without pwm, just like an On/Off switch on absorb/float only.
A+
Erik

[asdex]

I use aux 1 to turn a 24 volt relay on using waste not hi. The relay is also controlled by the thermostat on the cylinder. The relay turns on an 80 amp SSR which supplies a 24 volt 900 watt element directly from the batteries. The element draws about 35 amps I think from memory. 900/24=37.5A.
It works very well.

[dgd]

dgd  -  Could you elaborate on that wiring from two of your PV strings to the water heater element ?
  Is it like this
PV strings to rectifier to SSR to water heater element ?
You tie all the input on 3 phase rectifier together and use it only on the positive wire ?
Could you  sketch up a schematic for this ?

Almost right.
The PV strings connect to the commoned AC input side of the rectifier, the pos rectifier goes to pos Pv input in Classic.
Also connected to commoned AC input is the input to SSR, the ouput goes to the element.
The controls on the SSR go to AUX1 in Classic via a small on/off toggle switch and a 70degC temperature switch on HWC.
There is also a 10,000uF 200V cap on same commoned connector.
All of this and heatsinks for SSR and rectifier are mounted in an MNDV Ali box.
There are also an ac756 DC current sensor, ltc12000 dc voltmeter sensor in there that connect to a web monitor.

I will get a nice looking circuit diagram together soon.

dgd

[kauaisolarman]

do the classic-SL's have the same functions in aux 1/2 as the regular classics?

when i try to scroll through the different options that aux 1 has all that comes up is on/off/diversion  i do not have the option for anything else on aux 1. (there is currently nothing connected to the aux 1 terminals so i don't know if that has anything to do with it).

i want to try the aux 1 route and keep WBjr in operation.  what other options are there for aux 1 and taking advantages of diversion load other than diversion/waste not?

[ClassicCrazy]

I don't know anything about that Classic SL model except for what I just looked up on the Midnite site.
So it has no ethernet connector  - no way to use the Local Status App or other monitoring software ?
I use the Local Status App for setting everything up - and when I go into Config menu there are 16 options for AUX 1 .

I just tried it on the MNGP and found out I have to go to AUX 1 then there is a Setup button you need to push to see all the options.

Larry

[kauaisolarman]

ok so i installed the SSR today with the AC heating element taking power from my inverter.

Aux 1 does seems to have all the same options as the regular classics.

so i hooked the SSR to AUX 1 and tried waste not HI (was in float already battery 100%) but i am sot sure how to set it up as the SSR never turned on this way.

next thing i did was set it to turn on with Float HI and that worked.  it turned on the ssr and power flowed to the heating element.  when the voltage dropped below the float voltage the SSR would turn off and the CC would go into float MPPT to try to bring the voltage back up and battery back into float.

this was great but i still need to wait for float stage and wasting all the power during absorb.

can someone please tell me the best option for Aux 1 when using SSR diversion while in absorb stage?  if it is waste not HI how do i program it?  for example my absorb voltage is 30.6V and float is 26.7V  what is the best way to choose the voltages for waste not HI?

[ClassicCrazy]

There are four other setpoints  in Waste Not High - what did you set those for ?

Larry

[kauaisolarman]

thanks for the reply I just figured out how the aux 1 works.

1st voltage is set to when you want the SSR to turn off relative to the charge voltages (absorb/float) you set in the controller.  so if your absorb voltage is set at 30.6 and want the SSR to turn off when the voltage drops to 28.6 you set the low voltage parameter to -2.0.

2nd voltage is set to when you want the SSR to turn on.  it is also relative to the charge voltages you set in the controller.  so if your absorb voltage is 30.6 and you want the SSR to turn on at 30.5 V you set the high voltage to -0.1.

the delay time is how long you want it to wait after it hits the high voltage setting berfoe turning on the SSR.  the hold time is how long you want it to wait to turn off after it hits the low voltage setting.


this does not work fast enough and seems to keep me jumping in an out of absorb mode as my heating element can pull 1125 watts and there is only 200 excess watts when the absorb stage starts, so aux 1 turns on the element when the absorb stage starts and the element tries to pull 1000 watts and starts to drain the battery taking me out of absorb mode and not allowing a full charge cycle to be completed.

i am going to try the AUX 2 PWM waste not HI method but i am not sure how/what to set the parameters at.


it asks for "volts" and "width"

what should i set in these parameters and what to they mean?

sorry for the dumb questions but i know it will help another dummy like me in the future.

[kitestrings]

Say you start with an off-set of -0.5V, and a width of 1V.  If the absorb is say 29.6V, the PWM will start to become active (pulsing) at 29.1V, and become fully active - no longer pulsing, full on - at (29.1 + 1.0 =) 30.1V.

It will take a little trial and error to find the sweet spot.  The higher your diversion load the less "width" you will need.

[kauaisolarman]

thanks again for the helpful info.

got working on it today an heres the settings that i came out with.  only had a chance to work on it while in flow mode today so well have to wait and see how absorb does tomorrow.

anyway.

my factory float setting is 26.8V  the classic will stay in float mode within .4V then goes into Float MPPT.

my volt setting to keep me in the float parameters was 1.0
and my width setting to keep me in float was 1.0V

with these settings the classic keeps me at a constant 26.6V and stays in FLOAT.  it seems that the lower i set the "voltage" the classic wanted to keep me at a voltage too low for float and was keeping me in float MPPT.  the only setting that kept me within 0.2V of float was 1.0 "voltage".

also tried 1.0 "width" and worked well with the 1.0 "voltage" setting.  tried 2.0 "width"  but it just kept on aux 2 the entire time without pulsing on/off?

anyway  conclusion is that the PWM waste not works great for harvesting that extra power (during float anyway).  well see tomorrow if the setting i put in for float will work just as good for absorb.

all this got me thinking that this PWM diversion waste not is great but i do miss having WBjr to see my SOC%. 

will i get the same result if i use a diversion controller (morningstar tristar 60) and just run everything straight DC?

i would like to have this "diversion" feature and still be able to use my WBjr with aux 2 from the classic, seems a diversion controller is the way to achieve both.  any opinions on this?  anyone try this out?

[ClassicCrazy]

Maybe instead of putting money into another controller to do diversion you could buy more PV's and just connect them directly to heating element of water heater.  That way you get 100% of power to water heater unless the water temperature gets to temp setpoint .

Larry

[kauaisolarman]

thanks larry looked into that route also, but, i cant seem to find a high voltage DC thermostat that can work with the setup so the water doesn't boil over.

i was looking into this but not sure if its even needed (looks like just need it to run the AC thermostat)
http://www.ebay.com/itm/302133928592?_trksid=p2055119.m1438.l2661&ssPageName=STRK%3AMEBIDX%3AIT

anyone think it's worth it or should i just connect the PV direct to the heating element and not worry about thermostat control?


but this still wouldn't solve the problem of the wasted power and being able to use the WBjr and PWM "waste not" at the same time!

looking into the tristar 45.  going to try to use it in diversion mode directly off the batteries to the heating element and see if it can do the same as Aux 2 PWM "waste not hi".   this would free up aux 2 for WBjr use!

these controllers would be perfect if you could just hook WBjr to AUX 1!

[ClassicCrazy]

Inexpensive temperature controllers might work - you would run the small relay to higher rated SSR .

http://www.ebay.com/itm/DC12V-W1209-Temperature-Controller-Control-Switch-Waterproof-Digital-Display-/201315706969?hash=item2edf59e859:g:zjwAAOSw~otWfgyp

Larry

[dgd]

thanks larry looked into that route also, but, i cant seem to find a high voltage DC thermostat that can work with the setup so the water doesn't boil over.

You need a temperatre controlled switch. These usually have a flat sensor area that presses onto the heat area to be measured such as copper pipe from tank top where hot water is supplied from.
This switch controls an ssr that connects the pvs to the heating element
These switches come in preset temperatures, I use a 65degC one.
The switch is normally closed and opens when preset temp is reached
Dgd