Author Topic: Control for heating with solar off grid no batteries  (Read 28829 times)

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ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #90 on: November 21, 2016, 10:48:28 AM »
Just ordered the  4 channel opto-isolater modules.

Thanks

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #91 on: November 27, 2016, 03:34:40 PM »
[quote author=OperaHouse

These would make a much easier build.  They use a 5.1K pullup resistor for drive.  t would be easy to parallel another resistor under the board or parallel two channels to get higher drive.  There are not any suitable FET modules at this time for water heating, but hard wiring a couple FET is pretty easy. he IRF520 ones have too low a voltage and the IRF540 ones have no heat sinking and the copper  traces are too small for the current.

I ordered the  four channel opto-isolators that OperaHouse  found they are coming from
Hong Kong hope to have them in a couple weeks. This will be great to see them work. I
will let you know when they arrive.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #92 on: December 01, 2016, 05:27:16 PM »
While waiting on parts to get here,  have any of you guys put together a system to circulate
hot water ?  What kind of a pump is best,  rad to pump the water through ?

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #93 on: December 18, 2016, 06:51:16 AM »
I would like to thank OperaHouse  and you other ones for the help received on my project.
Have run into some health problems, maybe a bit of time before get back at it.

Thanks

george65

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Re: Control for heating with solar off grid no batteries
« Reply #94 on: December 18, 2016, 07:55:19 AM »

I was reading over this thread again today.
I would really like to build one of these but it's just way too far over my head. Seems like the posts here are like 1 in 3 out of the full discussion. :0)
No way I can figure it out without a connection diagram and parts list.
 Been looking to see if I can find something with them for about 4 hours today but can't find anything except ripoff priced commercial units.
I'm really surprised there aren't a load of people wanting to do this. I think a few have had the idea and been put off. I must have read 50 threads where people asked and then got people whining about not efficient and suggesting other things instead of just answering the question asked.
Hell of a lot easier to run wires to a standard heater than fool around with pipes and plumbing and other things for abortion or tube type heaters and a lot cheaper with power too.

Ah well, Maybe there is a cheap Chinese board I can find. No luck so far. 

Bruce S

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Re: Control for heating with solar off grid no batteries
« Reply #95 on: December 19, 2016, 10:51:00 AM »
george65;
I can be daunting to say the least. Getting back into writing programs for me is crazy hard.
I have to overcome my own short comings just to stay focused.
I've learned the hard on track with what I'm working on , not go play with a another one.
THAT can be the problem with an device that is so useful and cheap.

A kind word often goes unsaid BUT never goes unheard

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #96 on: December 24, 2016, 03:29:26 PM »
  Merry Christmas to everyone

  The very best in 2017

OperaHouse

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Re: Control for heating with solar off grid no batteries
« Reply #97 on: December 24, 2016, 05:07:35 PM »
Hope the new year finds you in good health and ready to continue with the project.  Have you added more space heaters to the array?

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #98 on: December 26, 2016, 11:06:28 AM »
The space heaters are still the same two  750 watt  240 volt.   Have had a lot of snow and
overcast with no sun in December.  Maybe in January with the days getting longer it will be better.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #99 on: January 19, 2017, 06:56:47 AM »
Got home from the hospital.  Hope to get this working.

OperaHouse

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Re: Control for heating with solar off grid no batteries
« Reply #100 on: January 19, 2017, 10:11:40 AM »
Welcome back. Thinking of posting to you this morning.  Don't know if you have read the electrodacus stuff.  Need to get you up and running before he does.  Like to compare your future results with his theoretical, both of you are in Canada.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #101 on: February 08, 2017, 08:43:57 AM »
Would like to get this working, don't know just where I have gone wrong. Have been very
thick and not able to get a grasp on this like other things through out life.  Open to any ideas
or suggestions.

OperaHouse

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Re: Control for heating with solar off grid no batteries
« Reply #102 on: February 08, 2017, 09:55:17 AM »
I'm working on a new water heater program now.  Let me know what you have for loads now so I can configure it for one or more resistive loads.   Need wattage and volt rating.  What is the open circuit voltage you measure from your array.   I've found a supplier near my camp.  Looks like I will be adding another 1,000W of Canadian Solar this summer.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #103 on: February 10, 2017, 08:58:23 AM »
Open circuit voltage in winter 170 's ,  have had a lot of overcast weather this winter starting to get some sunshine now,  next sunny day I will check the voltage and report it.
The load now is 1500 watt 240 volt baseboard heater on 6 panels.   
1000 watt 240 volt baseboard heater on the other six panels.

OperaHouse

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Re: Control for heating with solar off grid no batteries
« Reply #104 on: February 10, 2017, 10:29:41 AM »
That should be cooking a little.  I'm heading out of town and won't be able to do anything till Monday.  I'll edit up the new program for that voltage and email it to you.  This new program will track without external sensors.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #105 on: March 03, 2017, 08:04:28 AM »
Had bit of a set back.  Thanks for the new software.  Hope to get at this in a few days.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #106 on: March 22, 2017, 06:57:49 AM »
Need some help with the mosfets.  I used the diagram on page 1 reply#6 to wire the opto
and mosfets,  they carry the load and will not drop it. Disconnecting the wire to the gate
makes no difference.  The mosfets are  irpf250npbf  opto  4n26 . I am using  2 mosfets and
1 opto  there is power going to the gate. Maybe I need different ones or have not followed instructions ?

Mary B

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Re: Control for heating with solar off grid no batteries
« Reply #107 on: March 22, 2017, 07:11:14 PM »
Do you have voltage on the gate with it disconnected? If so you may have a bad FET.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #108 on: March 23, 2017, 06:51:10 AM »
I will check that and get back.  Thanks

OperaHouse

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Re: Control for heating with solar off grid no batteries
« Reply #109 on: March 23, 2017, 09:04:52 AM »
A FET can be damaged by a static charge to the gate. Puncture occurs when voltage on the
gate exceeds 20V. Even a minimal puncture can cause the device to fail a long time after
that has occurred.  It is a good idea to place a resistor from the gate to the source before
building the rest of the circuitry.  This will prevent damage from a floating gate either
in construction or an inadvertent disconnect. A failed FET almost always has a short from
the gate to the source. A floating gate can cause the FET to partially turn on causing
excessive heat and then failure.

So, it might be a good idea to have a pulldown resistor on each gate so if one FET is
removed or common is lost, the other one is still protected. A 1.5K resistor on each gate
would work.  That program is from another project I was working on and I changed the A/D
input and output pins.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #110 on: March 29, 2017, 06:39:47 AM »
Very Happy day yesterday I got the uno working.  The day was perfect for testing, heavy
overcast to bright sunshine back and forth several times.  Just have one pin operating at the
 moment but will hook up the other one.

DamonHD

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Re: Control for heating with solar off grid no batteries
« Reply #111 on: March 29, 2017, 08:35:40 AM »
Well done!  Hurrah!

Rgds

Damon

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #112 on: March 29, 2017, 09:43:16 AM »
Thank you. I hope to have a better understanding for the next ones.

OperaHouse

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Re: Control for heating with solar off grid no batteries
« Reply #113 on: March 29, 2017, 10:36:19 AM »
So, does it actually seem to hold the voltage at power point?  Are the FET running cool.  How big is the load?  Did you do anything to adjust it?

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #114 on: March 29, 2017, 11:15:31 AM »
Yes the voltage says at power point.  The load varied a lot through those conditions yesterday.  At the end of the day when I checked the load voltage was 18  the panels130.  Just have one fet operating off pin #3 it is hooked to a 750 watt  240 volt baseboard heater and the fet  is only warm.  Going to hook up another heater that is the same to operate off pin #11 with its own fet.  Have not done any adjusting yet,  could use some help with that.
I am going to take one of the panels out of series and put it back in parallel. That will drop
the voltage  by almost 40 volt. Will the code have to be changed ?

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #115 on: April 01, 2017, 11:14:48 AM »
 Installed a second opto-isolator and fet.   Got the second baseboard heater hooked up which
is controlled from pin #11 on the UNO.  Today is perfect for observing the performance heavy
cloud cover to bright sunshine changing frequently. Drive #1 , #2 vary from both on full power to partial  power on just drive #1.  Very happy to see this is working.  Want to let you guys that have been following this know.

DamonHD

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Re: Control for heating with solar off grid no batteries
« Reply #116 on: April 01, 2017, 01:03:52 PM »
Thanks for the update: it's good to know when things work, as well as when they don't!

Rgds

Damon

OperaHouse

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Re: Control for heating with solar off grid no batteries
« Reply #117 on: April 01, 2017, 01:11:41 PM »
Good job, you'll be doing a youtube video next. I'll need to do a 4 heater version next. It is tax time and the desk is cleared off for that for a while. How many adjustment pots do you have in the system now?  If you hav an old analog dc meter, it can be used to make the adjustment. Just tune for higher voltage. Software update will come soon. Buy more fets.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #118 on: April 02, 2017, 06:59:43 AM »
Will not be doing a youtube video.  It has been quite a trip for me getting this far.  I am starting to get a bit of  a idea of how and why this operates.  There are two adjustment pots
in the system now.  I have a old analog meter that can be used.  No rush on new software
just when it happens.  ( still in amazement watching the load on the drive  change on this one )  My plan was to have two systems,  six panels on each  one.  Should I be thinking different ?  Have more fets on the way.

ontfarmer

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Re: Control for heating with solar off grid no batteries
« Reply #119 on: May 08, 2017, 06:15:29 PM »
Just an update  to let you know that the unit is working.  The load is controlled so the solar panels maintains  power point voltage.  The fets only get slightly warm. A very slight change
of brightness to the panels and the load changes instantly.