Solar and Hot Water Cylinder Spike

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solarpete

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We have recently installed solar panels and are trying to optimise their efficiency, we currently have no means to store surplus energy.

The system is set up so as to power the HWC as and when there is some solar activity e.g. 9:00 to 11:00 and then again 13:00 to 16:00.

What we are finding is that when it powers up at 9:00 there is a relatively short spike of imported (30c/kW) grid power as it brings the HW up to temp - we are then basically exporting (7c/kW) back to the grid for the next 4 to 5 hours.

Is there anything we can do to restrict the power to the HWC? i.e. smooth out the current 9:00 spike.

 
As above.  You want what is generally known as a solar PV diverter.  It only sends power to the immersion heater when your PV is exporting (or would be exporting if you didn't do this) and it only sends just enough power to the immersion heater to stop it exporting.

It is completely automatic and works whenever there is spare power, no need for timers or anything else.

I suspect the OP may not be in the UK so you might want to look what is available in your own local marketplace.

 
This device would presumably invalidate any existing FIT agreement as it's a modification to the system, and it would probably amount to fraud if fitted without notification.

After all the pay-out, at least on my agreement, assumes half of what I generate is exported. 

The more careful adjustment of a timer is perfectly legal.

(My comments assume a UK installation with similar FIT agreement to my own.)

 
This device would presumably invalidate any existing FIT agreement as it's a modification to the system, and it would probably amount to fraud if fitted without notification.

After all the pay-out, at least on my agreement, assumes half of what I generate is exported. 

The more careful adjustment of a timer is perfectly legal.

(My comments assume a UK installation with similar FIT agreement to my own.)


It does not interfere with any part of the solar system, you fit the gadget to the immersion cct, with an 'amp clamp' around the meter tails to detect when spare energy is leaving the house. What you don't do is leave a timer in the cct, as this can be knackered by the Solic and the way it works, you can wire it in tandem to a timer, so you could set the timer for late afternoon to ensure you have hot water in winter months. What you don't want to do is set the timer for a tank of hot water in the morning. You want to use any hot water, or most of it,  before the panels start working. The Solic does have a boost button, but an automated timer is prefferable to that.  Customers tell me they get nearly all their hot water from their panels for 3/4s of the year with this gadget. Other versions are available with a timer built in, but cost a lot more.

 
OK, but I can't help thinking some rule or other must be being abused if you have a FIT agreement which pays for upload and a device which ensures none occurs.

I can't do it anyway as my bungalow has a combi and I'm not about to start re-plumbing it now.

 
energy still goes back to the grid, just less. There has never been any restrictions on using the energy generated, using all of it, has been the holy grail of solar for years

 
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