Direct to water heating.

[efficientPV]

I just added this separate 40 gallon tank in the garage just to wash clothes. I had hoped to just temper the water a little bit, maybe 75 or 80F at most. But this thing gets HOT and I can do three loads of wash. Over almost a week the temperature never dropped below 92F after three loads and was as high as 129F. The chart shows temperature 12" down from top of tank, it is stratified. Temperature for about a week went from 129F to 92F after three loads that day. Remember this is just excess PV power that would normally be wasted. The house and two other house tanks are heated by this same PV. The garage has lowest priority for energy diversion. Just goes to show how much energy most people are just wasting. The LG direct drive washer runs off raw PV power and needs no battery. This sure works nice. Tank has two 4500W 240V heater elements in parallel and the array is 60V to water heater. Two east facing panels on the garage are placed in series with the houses 60V to provide 120V DC for washer. When not washing clothes the garage 60V array is in parallel with the housed SW facing panels giving excellent recovery in the morning.

 

[Capt Bill]

Remember this is just excess PV power that would normally be wasted. The house and two other house tanks are heated by this same PV. The garage has lowest priority for energy diversion. Just goes to show how much energy most people are just wasting. The LG direct drive washer runs off raw PV power and needs no battery.

Wow ... Look great. I would like to understand more of your specifics ... including: How do you get a washer to run 120 vdc? (and not inverter?) Was that washer designed for DC current? ... What electronics or controllers do you use for dumping those panels to water heating? How do you get panels to heat other water tanks first, then then switch to garage for lowest priority for energy diversion ... Any chance you could give us a wiring diagram with specifics to possibly copy? What's in that box on top of that water heater? Those are question that came to my curious mind after Wow ! I would love to read more with a diagram if you have time. :+)

 

[TRW]

I have a question after reading this entire thread.

I love what you are all trying to do, I am struggling with what I should do to accomplish the same goal?

I kind of wish there was a synopsis of the thread. I have finally found people like me!

 

[efficientPV]

Some people are going to be building the board, not me, and it should be available in a couple months. We'll just have to see. It has been working great. Wife loves the clothes come out hot. It is a better wash than we get at home with the same machine. There is no thought about doing cold in any cycle to save energy.

 

[TRW]

This is very interesting. I don't understand why a person can't just connect a series of panels up and let them heat. I did read a lot a lot here in the forum, but still don't understand that. I do accept that it is necessary to manipulate the DC, but kind of wonder about it. I like the idea that this is a simple way of getting a few panels and making hot water for a person who is not wanting the investment of the grid tie.

 

[Capt Bill]

This is very interesting. I don't understand why a person can't just connect a series of panels up and let them heat. I did read a lot a lot here in the forum, but still don't understand that. I do accept that it is necessary to manipulate the DC, but kind of wonder about it. I like the idea that this is a simple way of getting a few panels and making hot water for a person who is not wanting the investment of the grid tie.

My thoughts: from Steve Poz experiments on YouTube, plus studying; and this take might also depend on size of panels used. I think upping the voltage by connecting panels in series (which gets multiples of higher voltage at same amperage) ... is when you could use some in between electronics (like MPPT or similar) to get most watts from your solar panels into heating water via a heater coil. AND if you parallel connect your solar panels (keep same voltage, but up your amperage ... which needs thicker wires to be safe) ... , then you could most likely get the full or most watts of your solar panels at heating coil without an electronic in between (with good match to heater coil). ... That is my take from studying before doing. Poz's experiments showed solar panels hooked up in series did not produce the watts at a water heating coil he (or anyone might have) expected, but the parrellel connected solar panels did produce the watts expected.

 

[Capt Bill]

Some people are going to be building the board, not me,

Looking forward to hearing more later.

 

[TRW]

Yes, thanks for your input and I will keep reading.

 

[sunshine]

This is very interesting. I don't understand why a person can't just connect a series of panels up and let them heat..

There are other threads where this is done

DC water heater element?

Has anyone tried these? Just wondering if they actually work. I was wondering what to do with extra energy from the panels I have.

diysolarforum.com

 

[Capt Bill]

This lesson spoke to me as newbie who is just studying this before doing it. Others might have a contrasted take. Bet this can be confirmed by repeating test: 3 panels in series connected to a heating element produced same watts output as one panel (or something like that ... 3 panels wired in parallel (instead of series) produced expected 3x watts (or something like that) at water heating coil:

... have to add after recent review of end of this clip, maybe series wiring can produce watts efficiently with a different properly selected ohms resistance coil. I still more learning by doing time to put in.

 

[TRW]

Thanks for the input. I am going to be watching for more input and testing and updates. There is a bunch to learn and comprehend.

 

[efficientPV]

This is very interesting. I don't understand why a person can't just connect a series of panels up and let them heat. I did read a lot a lot here in the forum, but still don't understand that. I do accept that it is necessary to manipulate the DC, but kind of wonder about it. I like the idea that this is a simple way of getting a few panels and making hot water for a person who is not wanting the investment of the grid tie.

A lot of people are just playing around and that is fine. Certainly those in solar have a sunny day attitude and like to think about those great sunny days. Most of the summer I could do pretty well with something put together hap hazard. Now that it is fall there are lots of clouds. My wife doesn't want to hear any excuises She wants showers, dishwasher, and laundry to have hot water. In poor sun a mppt system can put out four or more times the power than direct connect. That is not adding a panel or two. And there may be a limit to how many solar panels you can put out. Most of mine aren't even on my property. There is science to this and you just can't wish it away.

 

[Munchie33]

A lot of people are just playing around and that is fine. <snip> There is science to this and you just can't wish it away.

Everybody is just upset about the lack of awesome solutions. They are waiting for your DIY kit.

 

[sunshine]

In poor sun a mppt system can put out four or more times the power than direct connect.

In poor sunlight that may be correct. However it is 4 times a very small amount.
In full sunlight with matched loads the difference is nill.
15% over the full season is a figure quoted in mppt favor which is negated by throwing up an extra panel!

" My wife doesn't want to hear any excuises She wants showers, dishwasher, and laundry to have hot water."
Mine knows where the hws mains switch is!

Last year the mains was off from late Oct to Feb by using #1
If #2 can extend that period then it is a success!

 

[SolarBro]

https://mwands.com/water-heater-thermostat

Simple solution. Just need a DC element and this thermostat. Then you can do PV direct water heating for cheap.

 

[TRW]

Can you explain the difference in a DC and AC element? They both have to be a resistance wire, don't they?

 

[SolarBro]

Can you explain the difference in a DC and AC element? They both have to be a resistance wire, don't they?

I'm not completely sure tbh, but I'd believe the arcing nature of DC current is probably why.

 

[Camthecam]

emon do a water heater diverter 240 with a triac. hbpowerwall has a YouTube on low voltage heating.

 

[Jcline16]

i didnt read through the whole thread so it may have been mentioned already but isnt there a component made by electrodacus that can be setup for this method of heating water? its been a while but i remember watching a presentation video he did on youtube that seemed to be similar to this, i think using his SBMS and DMPPT components for heating a thermal storage medium like water or sand. it does seem to have its limits, mainly if you cannot add more panels, but for those with the space and who are not experts, maybe it would be an easier route than coming up with your own setup. apologies if this has been discussed already.

 

[efficientPV]

I like Dacian, he has a purity of essence. He never waivers from his cause of direct connect. Matrix man is an engineers dream. Keep combining various heaters till you have a resistance that matches a load. Fine if you are starting from scratch and can bury a bunch of wires in concrete. But who has a tank you can stick ten elements in and they all have to be custom. It is a binary function. Totally impractical for most. It is still the same principal, matching the solar panels to the load.

On heating elements. All have a metal sheath. Most have that sheath electrically connected to the base. The ones that are grey metal typically do not have an electrical connection to ground. You may even see a plastic insulator at the ends. While these tend to have very high resistance to the outside sheath there may be some very small leakage. Code even allows higher leakage. Out of an abundance of caution I would avoid these insulated types. Water heaters are such crap it is hard to say what caused them to fail. By four years the anode rod will be eaten away. Replace those periodically and it could go on forever. Or spend a couple extra bucks and get a good fiberglass tank like the Marathon.