It is excess power.If it's excess power already then there's no reason to overcomplicate things with DC.
The element that is in the water heater right now is 120 V 1500 W. When I purchased the water heater, I thought it was AC or DC but I didn’t know what I was doing. The sales rep was also dishonest.I think it comes down to cost vs complexity.
On one hand, finding 48v elements and running the required guage of wire to feed them is complex. You're going to have to spend money to buy specialty elements and thicker wires, and have some way of engaging the heaters only when you're in "excess power" mode which is probably something like a Hydro controller with dump loads terminals.
On the other hand, what is the wattage draw on that water heater? Even if it's only 120v you still need a way to invert that much wattage. It will be easier to wire up and you don't need specialty elements, but now you need to figure out some sort of relay system to only power on when in "excess power mode" which could be as simple as jacking into a remote switch or as complicated as an Adrino with a relay and supplemental power supply and the like.
Both options have their pro's and cons. My choice personally would be a standard 48v hydro controller for the dump load going to 48v elements. But I like the simplicity of that. The choice is ultimately yours.
So a 2kw inverter just to make sure I don't overload my 4400w inverter?Yeah, sounds like you're almost all the way there, you just need the DC elements and thermostats...
Or a 2kw inverter that can use the existing elements and thermostats that can be controlled by the whizbang.
Basically you're half way in between.
Basically, if you only want to use it as a dump load, but if you have to de-rate your inverter's output because the the heater might come on...
So what would this look like? Being I have two charge controllers. Would one of the two be connected to the 2KW inverter that would feed the water heater?
Thank youNo, both would connect up to your batteries as normal, you'd just need a dump controller to send power to the 2kw inverter (or toggle the remote power switch) to turn on when you've got the "excess power" available. Basically the dump controller would just be another DC load on the system and if it didn't exist there would be no change on the current system setup.
agreed... and when wanting to make it "smart" :If it's excess power already then there's no reason to overcomplicate things with DC.
I like this idea but the solution is probably difficult.Any really smart system would have proportional control. You can't imagine how nice it is to pull excess power directly from an array avoiding larger inverter and battery. And most PV systems have a lot of excess. As a bonus, my laundry has a separate tank just for washing and all cycles use hot water.
I am setting up to do that this Summer. I have purchased a new 30 gallon hot water tank that I swapped out the 240v-4500w elements with 120v- 2000w elements. This tank is replacing the present tank. My controls are a MTS to switch between grid and inverter supply and a simple 30amp 2 pole on/off switch already used now to control when I want hot water.I would like to us excess power during the summer months to heat my domestic water. What are the pros and cons? Should I go directly from my 48 V system or through the inverter 120 V?
It is currently set up for 120v.
I like that idea and thought of doing something Manually but I’m very seldom home during that time of day. Good idea though.I am setting up to do that this Summer. I have purchased a new 30 gallon hot water tank that I swapped out the 240v-4500w elements with 120v- 2000w elements. This tank is replacing the present tank. My controls are a MTS to switch between grid and inverter supply and a simple 30amp 2 pole on/off switch already used now to control when I want hot water.
The idea is in the afternoon when my batteries are charged I will switch on the hot water tank and run it for a couple of hours. That will give me hot water to shower and do a load of clothes or run the dishwasher. After which the water heater gets switched off. Since I do not need hot water all the time this should work. But I will see once everything is setup.