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Forum Index : Solar : Solar Off Grid.  PV Solar Matched to Heating Element .

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Murphy's friend

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Joined: 04/10/2019
Location: Australia
Posts: 671
Posted: 08:31am 14 May 2023
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  phil99 said  
Yes, as long as the switching 'on' time is short enough to prevent excessive burning and the 'off' time long enough to extinguish the arc.


Well, maybe. All thermostats are not created equal. If the contacts are slow to open or/and the opening distance is insufficient, it will create a DC arc when the contacts *open*.

Once the arc is established, 'off' time no longer plays any role as long as there is solar power and a load to feed it.
 
Confused
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Joined: 02/05/2023
Location: Ireland
Posts: 17
Posted: 11:29am 14 May 2023
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Hello Davo99,
             Yes, It was the Arduino board and the caps that I was referring to. I just wanted to get as close to what you  used and any other unit you used.

                                                             JS.
 
phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2407
Posted: 12:39pm 14 May 2023
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  Quote   phil99 said  

Yes, as long as the switching 'on' time is short enough to prevent excessive burning and the 'off' time long enough to extinguish the arc.


Well, maybe. All thermostats are not created equal. If the contacts are slow to open or/and the opening distance is insufficient, it will create a DC arc when the contacts *open*.

I worded that poorly. I should have said the 'on' and 'off' times of the MOSFET. The MOSFET 'on' time needs to be short so that if the thermostat opens while it is on you want the MOSFET to switch off before the arc damages the contacts. The MOSFET 'off' time needs to be long enough to ensure the arc has extinguished and prevent the arc re-striking.

Having the thermostat switch the gate or gate power supply is the safer option.
 
Murphy's friend

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Joined: 04/10/2019
Location: Australia
Posts: 671
Posted: 03:15pm 14 May 2023
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  phil99 said  

Having the thermostat switch the gate or gate power supply is the safer option.


Understood, that is exactly what my system does.
 
Confused
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Joined: 02/05/2023
Location: Ireland
Posts: 17
Posted: 09:49pm 14 May 2023
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Davo99,
        With what the lads are saying and what you say in your long post. In there
any modifications you'd make.  Any chance of a simple diagram.
                                  J.S
 
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