Moved from house with solar panels, advice please

Screwdriva

Mikeyboy01443 said:

I just use my immersion to heat water, i control it manually at the moment but i have bought a WiFi switch to control it more easily.
I didn't want to spend the extra hundreds on a diverter just to press a switch 

I used to do the same using a Wifi Spar. Now that Agile Outgoing is so much higher than import, I sell everything I can and consume as late as possible.

Reed_Richards

Dave_Fowler said:
And it's not only that; a switch is on or off - 3kW or nothing. A controller will mop up whatever power is available, so that every last Watt hour is used to heat the water.

It's better if you have a battery.  A switched immersion heater will always draw 3 kW but if that can come from either the panels or the battery then if the sun goes behind a cloud the battery can step up to meet the demand.  I typically run my WiFi-switched immersion for 20 minutes an hour over several hours which gives 40 minutes to recoup any charge lost from the battery. 

mickyduck55

Reed_Richards said:

Dave_Fowler said:
And it's not only that; a switch is on or off - 3kW or nothing. A controller will mop up whatever power is available, so that every last Watt hour is used to heat the water.

It's better if you have a battery.  A switched immersion heater will always draw 3 kW but if that can come from either the panels or the battery then if the sun goes behind a cloud the battery can step up to meet the demand.  I typically run my WiFi-switched immersion for 20 minutes an hour over several hours which gives 40 minutes to recoup any charge lost from the battery. 

You are a regular poster so I respect your view I guess you are in total control of the system and disciplined then its  fine.. but for many who are not aware, pop the kettle on at the same time or any other heavy draw appliance and you may exceed the available capacity.

Reed_Richards

mickyduck55 said:

You are a regular poster so I respect your view I guess you are in total control of the system and disciplined then its  fine.. but for many who are not aware, pop the kettle on at the same time or any other heavy draw appliance and you may exceed the available capacity.

That's entirely correct.  I may briefly draw some electricity from the grid when I boil a kettle.  If I was cooking (prolonged use of a heavy draw appliance) I would turn off the immersion heater.  My WiFi-switched system is certainly far from perfect but at current electricity prices I cannot justify the extra cost of a diverter and I was never convinced that a diverter would distinguish between excess solar and temporary battery discharge (e.g. when that kettle boils and turns off).    

70sbudgie

Reed_Richards said:

... and I was never convinced that a diverter would distinguish between excess solar and temporary battery discharge (e.g. when that kettle boils and turns off).    

It should do. The current clamp (CT) should be fitted to the circuit between the consumer unit and the meter, so only export power flow triggers the immersion. And even if the battery doesn't react quick enough to stop discharging after your kettle turns off, the duration of power flowing to your consumer unit will be very low and probably mopped up by other appliances before it triggers the immersion. I would imagine that the battery has a response time in seconds if not quicker.

70sbudgie

If I were to ignore Agile export prices, I am anticipating the pay back on my diverter to be less than 3 years. 

Obviously Agile outgoing completely changes the calculations.

jimjames

Dave_Fowler said:

mickyduck55 said:

Mikeyboy01443 said:

I just use my immersion to heat water, i control it manually at the moment but i have bought a WiFi switch to control it more easily.
I didn't want to spend the extra hundreds on a diverter just to press a switch 

I really don't get it... its not simply clicking a switch .. its clicking it when you have excess generation and clicking it again every time a cloud passes... Im retired so not really busy BUT I am absolutely certain I would switch the immersion on, pop to the allotment, the loo, shops and find I had used 1 - 3  kWh heating my water using mains power because I hadn't noticed it was cloudy / importing.  If its financially a good idea probably not if you have a good SEG (but if that's the case its not sensible to heat using electricity) but its been sat there for 6-7 years just doing its thing. 

And it's not only that; a switch is on or off - 3kW or nothing. A controller will mop up whatever power is available, so that every last Watt hour is used to heat the water.

Apologies if it's going at a tangent but hopefully relevant here. I've just fitted a Wifi switch but am looking at diverters. From what you're saying I assume the diverter prevents the immersion from taking the full 3Kw and just provides any excess to power it. If the tank temperature is reached does the excess go back to being exported again?

gefnew

Diverters only work on Resistive loads as they are a proportional diverter so if there is a spare 500 watts of solar and the back ground is catered for first,  then the 500 goes to the resistive load E G oil filled electric radiator hot water tank.

thevilla

jimjames said:

Dave_Fowler said:

mickyduck55 said:

Mikeyboy01443 said:

I just use my immersion to heat water, i control it manually at the moment but i have bought a WiFi switch to control it more easily.
I didn't want to spend the extra hundreds on a diverter just to press a switch 

I really don't get it... its not simply clicking a switch .. its clicking it when you have excess generation and clicking it again every time a cloud passes... Im retired so not really busy BUT I am absolutely certain I would switch the immersion on, pop to the allotment, the loo, shops and find I had used 1 - 3  kWh heating my water using mains power because I hadn't noticed it was cloudy / importing.  If its financially a good idea probably not if you have a good SEG (but if that's the case its not sensible to heat using electricity) but its been sat there for 6-7 years just doing its thing. 

And it's not only that; a switch is on or off - 3kW or nothing. A controller will mop up whatever power is available, so that every last Watt hour is used to heat the water.

Apologies if it's going at a tangent but hopefully relevant here. I've just fitted a Wifi switch but am looking at diverters. From what you're saying I assume the diverter prevents the immersion from taking the full 3Kw and just provides any excess to power it. If the tank temperature is reached does the excess go back to being exported again?

Correct. That's what diverters do.

Mikeyboy01443

Im not saying switch off immersion every time a cloud comes past, the immersion comes on and clicks off after a while anyway. And as was mentioned if solar output is a bit low it can borrow some of my battery.
I know a diverter would probably be better but i dont want to spend the hundreds to get fitted what i can just do manually.... and come winter with lower solar output i will probably just be using the gas to heat the hot water anyway, i can't imagine i will be exporting much anyway...