Solar overflow to run water heater?

[Carv]

Thanks Mike,
Matrix please put up the link. I'd like to read your thread as it looks like this might be my only option if I want to have my set up function like this.

Ok so if I understand it, you guys are suggesting 3 different ways to do this;
1) set up a new panel with separate system to power water heater
2) Change my water heater element to run at 60V instead of 120V or to DC
3) program the CC to direct the overage to the water heater, if my CC is capable.


Guess I failed to give enough information, this is on a box trailer running 2 -60 cell 255W, 8.5A, 30V, grid tie panels in series and I don't want to add any more panels, it would just complicate things more and there's not a lot of room left. I also don't want to alter my heating element in the WH as I still need to be able to run the water heater off the Genny's 120V AC as a back up in case there's a problem with the solar.
Here's the panel specs .https://www.solarpaneltalk.com/filed...9&d=1500058902

My WH element is adjustable and I have it warming to approximately 130F currently. 60F is not exactly a nice hot shower plus the hotter the water is in the tank the less I have to use ( blending with cold) getting a shower.

So I read up and I have the EPever 3215BN, I read the manual and it does not have any programing options for over flow. And from what I can tell the aux is just a low wattage pass through, looks like it's for a light bulb or phone charger, but I'm not sure on this?

I do see a problem even if the aux load is enough, and that is I'm assuming the auxload is DC?

Given my restraints is there another way pulling off the CC once batteries are on float? Even if I was able to do this, I'm thinking I'd still need to convert that feed from DC to AC?

[Mike90250]

I do the same thing but with a MidNite Classic CC. Works perfectly. I could link you to the thread where I set it up, but it is at the MidNite solar forum and this forum does not allow external links......

You can put one link, in response to a direct question, so go on ahead. Mod

[Matrix]

Also you can use a smaller element (as suggested). And remember, if you need to or can, you can use a 240v element in a 120v set up, and it will use 25%ish of the rated power. A 3600W 240v element when connected to 120v will only use 900 Watts.

[Matrix]

I do the same thing but with a MidNite Classic CC. Works perfectly. I could link you to the thread where I set it up, but it is at the MidNite solar forum and this forum does not allow external links.

If your CC has a Waste Not type feature (where it allows the use of excess solar power when available that is not otherwise used) it can be programed to only supply power to the water heater when certain conditions are met, say ... if the CC is in the absorb phase of charging at SOC 95% and the voltage is XX.Xv +/- .X volts the CC will supply a signal to power a water heater to the inverter using a SSR. So when the sun is out and the system is charged, if there is excess power coming from the solar only it will allow the inverter to power the heater. If the conditions are not met it does not. Then you never use battery to heat water, only solar. But I do not think your CC will allow that level of programing - you would need AUX outputs on the CC.

There is another way. But will require more panels and a separate sub solar system. It would work with your current system to supply power to the relays, but the water heating would be done y a separate set of panels. Go to waterheatertimer (dot) org and look for the article Convert AC water heater to DC. This would also work, but would work independent of your current system.

[PNPmacnab]

I have one of those 6 gallon tanks and I run off excess solar and 900WH will get it up 60F to temperature. If already warm, a lot less power. Surprising what you can do with just 6 gallons. I have a 36V and 60V array, each drives a separate tank off the raw PV voltage thru a special controller you can't get. This leaves the batteries intact. If you could find an auto transformer, one with a dual 120V primary and enough current, it could be wired to produce 60V. That would be 1/4 of the rated wattage of the element and not present a large load on the inverter. I put less than 400W in my tank and have reliable results. Some use a big light dimmer, but this still presents a heavy load that won't make the inverter happy.

[Carv]

So I've set up my system and it runs pretty good, most days it's in use, batteries are full or on trickle by 10am to 11am.

I also have a 6 gallon electric water heater I currently run off a Genny. I'm thinking I'd like to use the over flow from the solar pannels once the batteries are full to run the electric water heater... If it's possible?

Here's my set up
https://www.solarpaneltalk.com/forum...-wiring/page11

image_10129.jpg

CC is a EPever 30A, inverter is a 1,500 with 3,000 peak load and it has a 110v plug on top that my fridge is plugged into, inverter is currently set to sleep after load is gone and kick on when it senses load.

Water heater pulls about 13.75A (tested with kill-a-watt) and takes about 30 min to reach tempature. Based on this if I ran the water heater off the inverter it'd pull 1,650W (120vx13.74A). I can't remember all the math I had to do to set this up, but I'm thinking 1,650W /12v DC is 137.5A DC pulling from the batteries (+20% inverter conversion) is 165A DC for 30 min is 82.5Ah out of 214 total Ah on tbe battery bank would be 39.7% pull leaving me with 60.3% Ah left in a 30 min time frame.

I see a couple things wrong with this:
1) that's to deep of a draw down to be healthy for the batteries
2) The discharge rate is way to extreme and will cook the plates/batteries.

Since running the water heater off the battery bank does not seem to work ( unless I'm missing something), ...is there a way to run the water heater off the PV over flow once the batteries hit float charge and can this be done on some type of automatic switch so I don't have to be present to make it happen?


Thanks