Solar water heater

[willem wikkel spies]

So its still running. had to use all the hot water the other day at 12:00 o clock, by 17:30 the water was at 68 degrees.
i have only used 30 units on my electrical bill this month.
so a big middle finger for our eskom from my side!!

 

[The Terrible Triplett]

I’m wanting to put a couple of solar panels on to outbuilding roof and use output to heat immersion heater for domestic hot water ( I have boiler backup)
I don’t want a grid tied system - completely standalone
I want to keep the existing 3kW element as I don’t think it will come out of the cylinder!
Don’t want batteries- just want to feed the output via inverter direct to immersion
Is there an inverter that will do this?
Anyone done it?

What I realized, if you put up solar panels to heat a geyser, that geyser will be heated in a couple of hours.

So what then happens with the panels?

So a penny dropped ... get a Solis grid-tied inverter, slap the panels on it, connect it to the main DB, put in a timer for when to switch the geyser on, like a Shelly relay that gets one very far ito what time/s to come on and with a temp sensor, for when to switch on/off if the geyser temp is too low/high, and one can automate it all.

Can even use Home Assistant/NodeRED if that is ones flavor.

Then when the geyser is heated, when the solar panels are sitting idly on the roof, use that free power for other loads in the house.

My 2 cents.

 

[Daddy Tanuki]

What I realized, if you put up solar panels to heat a geyser, that geyser will be heated in a couple of hours.

So what then happens with the panels?

So a penny dropped ... get a Solis grid-tied inverter, slap the panels on it, connect it to the main DB, put in a timer for when to switch the geyser on, like a Shelly relay that gets one very far ito what time/s to come on and with a temp sensor, for when to switch on/off if the geyser temp is too low/high, and one can automate it all.

Can even use Home Assistant/NodeRED if that is ones flavor.

Then when the geyser is heated, when the solar panels are sitting idly on the roof, use that free power for other loads in the house.

My 2 cents.

The TT, I looked at link real quick but how do you program it? via bluetooth or what? how does it work? sorry not up to speed on IOT and home controls.

 

[The Terrible Triplett]

The TT, I looked at link real quick but how do you program it? via bluetooth or what? how does it work? sorry not up to speed on IOT and home controls.

It comes with a nice easy-to-use interface, type in the IP address at home using any browser, or on your phone at home, and you can get to it.



I connect it like so, to a bigger relay, being 3kw element, just because it made sense to me, less stress on the Shelly.

 

[The Terrible Triplett]

FWIW, that Shelly, it is controlled, in my case, by NodeRED running on the Venus/Cerbo Large OS.

When the solar panels are >3.6kw, utilities draw is near zero, the "Victron system" switches on the Shelly to heat the geyser up to 50 deg Celcius. Can adjust higher if I want.

Then, as long as the utilities draw stays below 600w, to cater for house loads coming on in that time, the geyser will stay on.
EDIT: For bad weather days, late afternoon the geyser will switch on if the temp is not reached.
Evenings, IF the temp goes below 30 deg C, the geyser will go on ... I call it the "marriage saver" setting

The NodeRED part to switch the geyser on/off based on solar production, utilities draw:

 

[Daddy Tanuki]

It comes with a nice easy-to-use interface, type in the IP address at home using any browser, or on your phone at home, and you can get to it.

View attachment 211466

I connect it like so, to a bigger relay, being 3kw element, just because it made sense to me, less stress on the Shelly.
View attachment 211467

so could you hook this up to measure the temp of a tank, and the voltage of your battery bank and have it turn on a load as long as voltage is greater than or equal too xx.xx volts, and water temp was below say 80°c?

Scenario is a 1600 liter tank that is a hot water boiler using two 4500 watt heating elements in series. when battery is over lets say 53.9 volts the "shelley" could turn on a relay to the elements that allows voltage to flow.

why? I am over paneled for winter months, winter the battery bank is generally full by 1030-1100 and floating. On bad days it might not hit float but generally it does. (free hot water all winter?)

In the summer I run a a/c split pack 24/7 for humidity control and yet my bank is generally full by the same time.

So if the "shelley" can control taht it would automate something I have been trying to piece together.

 

[The Terrible Triplett]

So if the "shelley" can control taht it would automate something I have been trying to piece together.

Shelly is just the on/off switch, it needs to be told when to do that, its built-in software the catchall if you want.

Hence I use NodeRED on the Victron Cerbo as the "instructor" of the shelly, using the volts if I wanted. I chose to rather use the panel's incoming watts.

 

[willem wikkel spies]

just a update.
We had two days of really bad weather.
a cut off low which caused complete cloudy days.
highest was 38 degrees the one day and the other day it was 42 degrees, which was still not too bad.
so the solar panels could not heat the system to 75 degrees celcius as we had no sun.
it was not such a concern as we could see the water temp was down and we quickly boiled some water.
our day temps was around 26 degrees and night temps 20 degrees.

since then we just had plenty of sun, and water has been up to 75 degrees at 10:30 in the morning.
so we need to plan for things like this, and it is easy.

now, to use excess power, when you have it.....

so, if you need solar and you do not have solar, then what?
so using extra solar for something else can work, but if you cannot give power as you planned, then there is no use to budget/ think about it.
a full day of solar is not guaranteed!
just plan your system, see that it works and live with the fact, that at times you will have excess power, but it will still be waisted.
you cannot drink the last drop of every bottle water.

you can thank and pay me later for the above information.

ohms law is wrong, do some research lol

 

[The Terrible Triplett]

you can thank and pay me later for the above information.

Living in Cape Town, trust me when I say, you are pretty aware of the weeks of the year when you will have to fall back on utilities.

Living in Canada, Alaska, some USA states, Europe, and you have a whole new world of challenges to sort for months at a time.

You gain this experience from being on solar for more than a year.

Living where you live in South Africa, after a year you may look at it all again and think: I have these panels, they just sit there idling, the geyser being heated. How can I use that wasted energy just sitting there, already paid for?

You have to walk the talk first in your own shoes.

You can thank and pay ME when you are ready.