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Maximise output from PV system

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Mac4

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My PV system has a maximum output of 3.6 kw, this is constantly changing depending on the sun light hitting the system. What I would like to do is monitor the ac current produced by the pv system inverter so if it is producing 1 kw or more it will switch on the supply to a 1 kw immersion heater. I would also like to monitor say the kitchen sockets circuit so if a kettle is switched on the immersion would switch off until the kettle is done. so basically monitor 4 amps on both circuits to switch on and off the immersion.
Someone suggested using a current transfer coil fed into a LM311 possibly via a 741 amp.
I am a qualified electrician but have a limited knowledge of designing a circuit like this, I would be grateful if someone could help with a design I really want to build this and make it work.
Thanks

Alastair.
 
G'day Mac4,
First of all welcome to the forum mate :) Now some info on your system would be nice to get like are you off the grid or is this grid tie ? If you are off the grid what is the voltage and size of your batterybank, inverter type and capacity and do you use a mppt ?

Regards Bryan
 
Hi Bryan,
Thank you for your reply, The PV system is grid tied (connected to the grid) it is a MCS approved installation so the entire PV system must stay as it is and not be modified it has to be connected to the grid to work. However the AC output from the inverter is a 2.5 T&E cable it is possible to separate the live conductor and fit a coil around it to monitor the current. The AC output from the inverter feeds via a 2.5 T&E through a meter ( this measures the power generated by the PV system) then it connects to a spare way on the consumer unit. PV system max output is 3.6 KW, I'm not sure what mppt is?
If you need any more info please let me know.
 
This is standard electrical stuff and can probably be simplified. For now I will assume AC voltage and current. and 100 VAC to simplify math.

1KW would be 10A in the above case. You can determine if > than 10 A is being fed to your house with a current sensor such as ones from SSAC Timers & Controls Home Page, so that's your diversion.

The second part would be if the kettle is on (> x amps) turn the imersion heater off.

It's less complicated than your logic but should accomplish the same. Divert power > 1 KW (measured value is Current) to resistive heating with priority given to the kettle.
 
Wow I'm not sure what the above means either . The URL is to the home page which is useless if you don't know what you are looking for .
In this day and age you can find the part you know of ,get it up on screen and copy the URL . Just as easy as posting the home page URL.
Maybe this is it ? http://www.ssac.com/standard/ff-tcsa.htm but the scale here is 0-5 amps ,dunno if its adjustable

MPPT http://en.wikipedia.org/wiki/Maximum_power_point_tracking

The guy likes to ask for a whole heap of info right up and give you little after you have done all that.

I would wait for others to post and they will try to answer you ,Kiss is at least a starter
 
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In order to measure current flow there has to be a load. What will the load on the PV array be when the output is < 1kw and the heater is switched off?
 
Not clear how this will work. If the heater is off, how do you know that the PV unit is supplying >1 kW? Where is the power going? If the 1kW is already going into another load then there may be insufficient to power the heater too.

Alec
 
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