24h switches on electrical board for hot water


Old 08-14-15, 04:39 PM
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24h switches on electrical board for hot water

Hi, I really need some advice. Our setup is we have solar panels and 3 hot water tanks which were connected to an off-peak meter. We were getting some electrical jobs fixed anyway and he suggested the hot water tanks are connected to a 24h timer and attached to peak power, turning on when the sun is at its hottest. The theory being they will use solar power and be effectively free.

Since the change, something is disastrously wrong. Our bill will by estimates triple. On auto (off until 11 to 3pm) some nights we used 34kwh. Before, our daily average was 11. I did a test, switched all 3 hw tanks off with the switch and we used 10kw that night, not 34. The electrician came back and said he could not see anything wrong. That night l put one hw tank on auto and we used 17kw. Still we seem to be exporting about 10kw a day. I can't understand at all what the issue is. It's like the switches all don't work or are misconfigured. The hw tanks seem to ignore the solar just pull peak power and ignore the switches too. Has anyone got any idea what might be happening? I am taking readings twice a day and every day to try and understand. Thanks!
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Old 08-14-15, 04:45 PM
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Welcome to the forums.

he suggested the hot water tanks are connected to a 24h timer and attached to peak power, turning on when the sun is at its hottest.

You should be using only your solar panels during the day. The timer(s) should be set up so the power is turned OFF to the electric water heater during peak electric rate time.

Based on typical peak system..... you'd want the timer turned on from 9:00PM-6:00AM and off from 6:01AM-9:00PM.

You should fill out your location too.
Old 08-14-15, 06:43 PM
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Without seeing an actual schematic of your system you'll not get much more than a guess at what your problem is. I believe it's possible that before the electrician changed your timer that the power to the water heaters during peak hours did nothing as the water heaters were satisfied by the solar power so no electric power was used and at night power was off to the heaters and water wasn't heated at all by any source. Now that the timers have been changed, you obviously are heating water at night where you weren't before. I would also look at the thermostat settings on the heaters and also at hot water demand at night. Do you really need hot water at night? Can you get by with a lower temperature at night when you have to pay for the power to heat the water?
Old 08-17-15, 07:24 AM
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Worst case would be if your roof panel pump is running at night (making it a solar water cooler) and the electric heating element is on. We would need a full schematic of the system with current configuration to really tell what's going on.
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