Solar panels and hot water

4 Replies 16789 Views

Can I switch my hot water service from off peak to day time to maximise the use of power being generated and drawn from the solar system?  We don't use all the power currently generated and a lot goes back into the grid with little financial benefit to us.

0 Replies 922 Views

Because this graph (or chart) only gives a single indication for each hour, I think it's hiding your problem. 

I still think you don't have enough battery power. To me, it looks like the off-peak comes on, and the battery runs for as long as it's able before reaching it's cut-off point and the off-peak continues to draw about the same amount of power as it did initially, so the graph levels are about equal. Now that your battery is technically flat, the chart shows small usage for the rest of the night (probably lights, fridges etc). In the morning solar starts to charge and build up a reserve in your battery, and seems to drop off in the afternoon (cloudy day, or shade from something OR, panels not facing North ??? ). The last option is one I've seen often.

Any way you look at it, I personally will be planning on installing twice as much battery  power as I appear to need (at least a 5kw 48V setup to start), and at least enough solar panels to be able to charge them fully on a cloudy or rainy day. ( P.S. It would be nice to see a continuous chart for each full hour, instead of a single hourly total. Did the chart come from your charger, or from AGL???) ...... Cheers ... Jok. 9Dec23

1 Reply 675 Views


Im having a similar argument where I am producing enough power at the same time my Control Load 2 kicks in during the day. When I look at 5 min intervals I still have a lot more Solar then the control load is using. 


I am being told this is how it is.... there is 2 different meters for Controal Load and Mains... and the solar will only impact the mains. It will never have any effect on the Control Load. So much for trying to be sustainable and reduce my carbon foot print...


But when talking to the Network provider, they have explained that its due to the Electrical provider and how its being charged. 

So... where to from here?

0 Replies 668 Views

My solution was to replace my hot water system with a heat pump, with internal timer of the heat pump to heat between 10am and 4pm each day using at the most 2kwh in the middle of the day on solar v's 8-9 kWh at night on off peak. Electrician can hook it up at the time of replacement. My battery at night covers me and the sun during the day does my house, my water and feed back to grid. Making me about 95% self-sufficient.


Whilst it doesn't make sense in an environmentally conscious world that when you put solar on that your off peak solution should default to heating during the day during peak supply of green energy(utilising the solar not the grid), we are told there is an over supply during these time hence why FIT's are now so low.


Individual households are still left to find these solutions v's retailers facilitating them.

1 Reply 96 Views



I have solar and a battery. I have electric hotwater, off peak. Which heats from 10.00 pm to 7.ooam.

However I have been advised, my hotwater, is not connected to the battery. So it will charge off peak rates from.the above times. Is this correct.


My electrician has advised, he can in stall a smart switch, which will heat my hotwater tank during the day directly fro the solar, if sun is out. If no sun is out the smart switch pushes my hotwater to heat up back to to the night 10.00pm to 7.00pm.


To install this smart switch it about $1500

I have heard it's wonderful, if you have a battery and send a lot back to the grid which I do.


Can anyone else confirm ??




0 Replies 83 Views

If you have CL for your HWS, and it is set to run in off peak hours, it will (should) charge at the special CL off peak rate, which is less than normal meter off peak pricing.

It's still high though as compared to solar hours and / or shoulder rates 1000 - 1500.


We are in same situation, was offered a HWS diverter to put into the system, a smart device, but $1800 ??


No thanks . . .


All you need is a dumb timer on the HWS, one that can be set to come on between say 1000 and 1500 daily.

It will use your excess solar production, apart from winter perhaps if the solar isn't up with usage, it will then take from grid in those hours with the timer for shoulder, when it will use the cheapest tariff from the grid for CL shoulder rate.

* If you are on EV Night Saver rate, you can set such a timer in winter for 0000 - 0600, when you can use for 8c, and same for topping off a battery in those hours, all power going into the home at those hours is charged at 8c.


Now you'll have to check YOUR plan, YOUR tariffs, because all states are different.


The ideal thing for you perhaps, is get rid of CL metering altogether, just use your battery / dumb timer as needed.