How to Wire Water Heater to Gen SmartLoad of Sol-Ark 12K?

[DesertLuddite]

I've recently had a new hybrid solar system installed at our home: 14.8kw solar (40 panels at 370w each, 4 strings of 10), Fortress Power eVault Max 18.5kwh, Sol-Ark 12K. I've finished wiring in all of the circuits I want on my critical loads panel, and everything seems to be working fine so far, but I'd also like to take advantage of the SmartLoad capability where I can use the Gen Input as a controlled AC output for "luxury loads. In this case, I'd like to wire in my hot water heater.

The Sol-Ark manual says, "Using Gen load for a water heater, we recommend that only one leg (120V) be connected to the bottom element. This significantly reduces the power consumption of the water heater while retaining core functionality (it will heat water, only slower). Gen Load is limited to 50A at 240V (Do not exceed!)"

I'm fine with configuring the Sol-Ark software to achieve this, but I'm unclear on exactly how to physically wire this solution. Do I literally just pull one of the legs from the existing water heater breaker and connect it to one of the two inputs on the Sol-Ark Gen Breaker? If so, does it matter which leg I pull and which side of the Gen breaker I connect it to? Or is it saying that I actually need to hobble the water heater itself so that it only pulling 120 instead of 240, only using the lower of the two heating elements? In which case, my wiring question on the Sol-Ark side remains.)

 

[acsscott]

You would need to leave the leg that goes through the thermostat connected to the heating element, and connect the other heating element terminal to neutral. I don't think this is a good practice because it makes an uneven load on the inverter. Maybe they mean to wire the upper and lower elements in series so that it still uses L1 & L2, but draws less current because the resistance is lower? A 4500 Watt heating element should only be ~18 Amps. It heats the top element first, then switches to the bottom.

 

[mgdean]

So I am in the process of doing this myself. My plan is to use the electric water heater as the first stage before my propane water heater. I am replacing the two 240v 4500 watt elements with two 240v 1500 watt elements. The main reason I went with 240v 1500 watt elements is (1) lowers my amperage and balances the load compared to 120v 1500 watt element. (2) that's what I have for readily available protentional energy once the batteries hit 85% and start to taper off the demand of the PV. Any larger usage and I would not have enough excess PV to cover the full load, so the system would need to pull from the batteries or the grid to heat the water. If I'm draining my batteries of pulling off the grid it pretty much defeats the purpose of what we are trying to do. I am not sure how much power your putting on the grid or what excess potential energy your dealing with. If you have 4500 watts of excess on your PV for a minimum of 4 hours. I say go for it, as acssott pointed out its only drawing 18 amps. But realize once you meet your minimum PV wattage and battery charge requirements the smart load will turn on. If you don't have enough PV output of your sol-ark will go looking for the extra watts and it will not shut off until your PV wattage or battery charge fall below your requirements.

 

[acsscott]

I like the idea of replacing the lower element with a 240v 1500 watt element just so the demand is lower after the top of the tank is heated. It is still going to take the same amount of total watts with either element to raise the water x degrees.

 

[mgdean]

I completed the install the evening of the 10th and the smart load has been working great. Attached is the last couple days on the solar assistant. I was really surprised the heat it generates in the 4 to 6 hour during the winter. Looking forward to see what it does this summer. I have also been tracking my propane water heater with my Sense energy monitoring unit after I installed the preheat unit. I have seen a noticeable drop since I went live . It's only been ten days so take it what its worth but the data shows about 56% reduction, but time will tell.

 

[OlderDIYer]

I'm going to add to this thread rather than start a new one because the title closely matches the info I was searching for (but couldn't find much).

I'm about a month into my install and tweaking of my system and I have been interested in automating to make good use of the solar energy while it is produced. The smart load feature on the Sol-Ark seemed to be the solution but the actual use of it had eluded me until just now.

I had already done some work on using hot water heaters as a good place to "park" the energy. I replaced my very old 40 gallon electric heater that had 2500 watt elements with two new 50 gallon water heaters. I replaced the 3500 watt elements in each heater with 2000 watt elements (not very common) to better match the load to the Sol-Ark (instead of the 120 volt solution Sol-Ark proposes which causes confusion as shown above). I plumbed the two heaters in series of course and the wired them in such a way that the elements would kick on sequentially from hot water output to cold water input (found this technique on YouTube with link below).

I also interlocked the water heater power with my other big household load, the HVAC unit. I did this by tapping the thermostat wire 24 volt connection corresponding with the compressor running (the Y wire) and tieing that to the 24 volt coil of a double throw relay (link below) so that when the HVAC unit is running it cuts power to the water heater. This insures their loads don't stack and load up the Sol-Ark too much.

With all that done I still wanted to automate the process of running the hot water heaters only when the sun is shining enough to power them from solar instead of pulling from the batteries. That's where the smart load feature comes in and I just hooked it up today.

I wired the Gen output breaker on the Sol-Ark to a small load center so I could breaker the output to a 2 pole 30 amp breaker to match the wire size feeding the water heater cluster (# 10). Then I set the smart load parameters on the Sol-Ark and so far it's working perfectly! The main display on the Sol-Ark displays the word "Smart" in red letters on the animated power flow arrows. And when looking at the digital info screen one box in the lower right is now labeled "SmartLD" and shows the current flowing only to the smart load. The increased load shows up in PowerView but is not singled out in any way.

I should note that all this works for me because I'm a single person household and the amount of hot water I use can be built up slowly over time. I can take long hot showers and never run out of hot water even with no heating done overnight or when HVAC is running. But if you use more hot water it would probably work just to add more water heaters!

Relay I used to interlock HVAC with water heaters https://www.amazon.com/gp/product/B000LEUJU6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1


YouTube on wiring water heater sequentially.

 

[efficientPV]

I never realized that so many people have elephants and how often they have to be washed often.

There are 3/4 inch NPT heating elements that will fit into the drain port which will allow you to put some heat into a gas water heater. I have a minimal system and manage to heat enough water. The idea of pre heat tanks is appealing. I have one because my primary is very small. Small tanks heat really fast. Mosty pre heat tanks lose much of the energy put into them. Typically, it takes a continuous 75W just to maintain temperature. Suspect a gas water heater is even worse.

 

[OlderDIYer]

I never realized that so many people have elephants and how often they have to be washed often.

There are 3/4 inch NPT heating elements that will fit into the drain port which will allow you to put some heat into a gas water heater. I have a minimal system and manage to heat enough water. The idea of pre heat tanks is appealing. I have one because my primary is very small. Small tanks heat really fast. Mosty pre heat tanks lose much of the energy put into them. Typically, it takes a continuous 75W just to maintain temperature. Suspect a gas water heater is even worse.

Not sure I understand the elephant reference.

If I had a gas heater I'd would change it for electric after a solar install.

The new water heaters I purchased were nothing special off of Amazon but they are very well insulated and hold the heat quite well. I'm only looking to hold for a day so I can take a hot shower in the morning or late at night or on a cloudy day.