Bummer news on the 24V 1000 watt element. I went to test fit it in the hot water tank and it cannot be fully inserted due to obstruction. The exhaust flue inside the tank interferes. So major bummer ๐
I went ahead with the bench testing to explore the concept. Element was directly connected to 12V battery system to take measurements. I used the wiring I have put in place for diversion load which is about 30' of 8 gauge wire terminating at the outside access of the water heater with an SAE connector. The element is wired up with an SAE connector so I can plug it in at the outside access of the water heater.
Overcast day so solar wasn't contributing much. I think it was about 3 amps during testing.
Measured 10.7 V at the heating element. Battery voltage was about 12.8V and gradually dropping as load pulled it down.
Measured 23 amps with clamp meter at the element
Measured 0.7 ohm resistance for the element
It was heating up, I sure wish I could take it further and use it in the tank. When prepping the connections, I went ahead and slid some of that high temp heat shrink on the wiring in case the original heat shrink cooked off like during the previous test with the 12V 300 watt element. I didn't activate the heat shrink, I was waiting to see what would happen first. It seems like the wire heated up enough to activate it on its own and on one lead it split. I only had things running for 10 minutes or so. I don't know if it would have cooked the original heat shrink or not. The original stuff looks to be in great shape though after the 10 minutes.
I went ahead with the bench testing to explore the concept. Element was directly connected to 12V battery system to take measurements. I used the wiring I have put in place for diversion load which is about 30' of 8 gauge wire terminating at the outside access of the water heater with an SAE connector. The element is wired up with an SAE connector so I can plug it in at the outside access of the water heater.
Overcast day so solar wasn't contributing much. I think it was about 3 amps during testing.
Measured 10.7 V at the heating element. Battery voltage was about 12.8V and gradually dropping as load pulled it down.
Measured 23 amps with clamp meter at the element
Measured 0.7 ohm resistance for the element
It was heating up, I sure wish I could take it further and use it in the tank. When prepping the connections, I went ahead and slid some of that high temp heat shrink on the wiring in case the original heat shrink cooked off like during the previous test with the 12V 300 watt element. I didn't activate the heat shrink, I was waiting to see what would happen first. It seems like the wire heated up enough to activate it on its own and on one lead it split. I only had things running for 10 minutes or so. I don't know if it would have cooked the original heat shrink or not. The original stuff looks to be in great shape though after the 10 minutes.
Test is up and running. I disconnected one of the panels so I'm back to 280 watts total solar array capacity. Using the older of my 12V 300 watt elements. Things seem to be working as expected - battery voltage rose until reaching the absorption setpoint and then diversion started occurring while battery voltage remained constant. I took voltage readings on the diversion load and they are unexpectedly low. When battery voltage is 14.5V, the diversion load voltage is 9.2V with about 9 amps being dumped into heating element. It started the day at lower voltage than this and has settled around this value.
SCC is now in float mode (battery at 13.6V) and the diversion load voltage and current remains about the same. I measured voltage at the SCC terminals and at an Anderson quick-connect close to the SCC and both read 9.2V. I measured at the heating element and it was in the 7V range - voltage drop from 8 gauge wire running the entire length of 27-foot TT? Is this what anyone else expected? I thought I'd be seeing battery voltage or even panel voltage. Current at the element measured via clamp multimeter concurs with laptop SCC monitoring software. The diversion load voltage measurements at the SCC also agree with the array/load voltage value reported by laptop SCC software.
Temperature gun said that the wire leads leading into the heating element are 330F. These are the now-exposed wires that cooked off the heat shrink during initial day-long test run where I suspect I was simply putting too much wattage into the 300 watt element.
SCC is now in float mode (battery at 13.6V) and the diversion load voltage and current remains about the same. I measured voltage at the SCC terminals and at an Anderson quick-connect close to the SCC and both read 9.2V. I measured at the heating element and it was in the 7V range - voltage drop from 8 gauge wire running the entire length of 27-foot TT? Is this what anyone else expected? I thought I'd be seeing battery voltage or even panel voltage. Current at the element measured via clamp multimeter concurs with laptop SCC monitoring software. The diversion load voltage measurements at the SCC also agree with the array/load voltage value reported by laptop SCC software.
Temperature gun said that the wire leads leading into the heating element are 330F. These are the now-exposed wires that cooked off the heat shrink during initial day-long test run where I suspect I was simply putting too much wattage into the 300 watt element.
