Measuring and acting on solar export


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Davo99
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Joined: 03/06/2019
Location: Australia
Posts: 1507
Posted: 04:27pm 10 Jan 2022      

  Haxby said  
This will make the load around 1.4kw instead of 3.6kw


I think this overall it's better to lower the power of the element.
Much easier for a system in not so great weather to generate say a couple of kw that may meet all the home needs than 4 Kw+.

I have asked someone To do a program for an arduino for me that is basically a voltage controlled switch.  I want to try a couple of things with it including a staged output depending on voltage.  To this end I could have multiple elements and switch them in according to the rise I got from the solar. Still waiting for them to get back to me, beggars can't be demanding. Once I get the base program I think I should be able to copy the main part and attach that to different voltage dividers and assign different pin outs to control relays or mosfets.  Just not able to work out the code from scratch.

Before Xmas I bought a 6 Kw element which is 3x 2Kw elements. It's supposedly for 3 phase but with removable links, is easily made into 3x single phase elements.

The beauty of this is I could also direct connect it to panels with Ohm matching which would give a lot of combined power.
Better to use a controller though so the ohm matching is not required.

This may also be something for you to consider. Take the hot water off your solar all together and set it up on it's own system. You could get some used panels and just hook them up with a DC relay though the thermostat.
With a DPDT relay, you could also have a manual over ride so if the weather was bad you could top it up from the mains.

Being a 3.6 element, 4x350/ 270W panels would supply around a KW so might be enough for your needs over a day. You could add more panels using the controllers that have been published here a while back.
Edited 2022-01-11 02:32 by Davo99