Water heating through SCC

[Whats-n-Watts]

Trying to work out some water heating and was wondering if it's possible to connect PV to a SCC and connect the element to the battery side of the SCC. Of course controlled via DC thermostat. i was thinking that would maximize the power to the element as well as regulate amps and volts. Is that possible without involving a battery?

Thanks!

 

[sunshine_eggo]

Trying to work out some water heating and was wondering if it's possible to connect PV to a SCC and connect the element to the battery side of the SCC. Of course controlled via DC thermostat. i was thinking that would maximize the power to the element as well as regulate amps and volts. Is that possible without involving a battery?

Thanks!

A Victron SCC could do this, but it would need to be programmed for the desired voltage with a battery attached. After that , it can power resistive loads purely on PV without a battery.

Most MPPT require a battery to operate.

 

[sunsurfer]

A fix voltage would allow for a good match to the resistive load. Not the most efficient way to make heat but simple and reliable.

 

[Pierre]

I ran my water heater ( 230v 3kW element ) directly from an array of 5 x 460w PV panels for many years, no mppt. When on temperature the PV was switched back to the inverter ( built-in mppt ) etc.

 

[Bongbong]

Trying to work out some water heating and was wondering if it's possible to connect PV to a SCC and connect the element to the battery side of the SCC. Of course controlled via DC thermostat. i was thinking that would maximize the power to the element as well as regulate amps and volts. Is that possible without involving a battery?

Thanks!

You can easily do that, switching DC is the hardest part, while voltage and current can be less than the element max.

 

[Whats-n-Watts]

You can easily do that, switching DC is the hardest part, while voltage and current can be less than the element max.

I found some true dc elements as well as thermostats in 140 and 174 degrees. If they aren't full of it that is. Hopefully not and that will simply thing maybe.

 

[Whats-n-Watts]

You can easily do that, switching DC is the hardest part, while voltage and current can be less than the element max.

I found some DC thermostats so hopefully they will handle the switching on and off.

 

[Whats-n-Watts]

A Victron SCC could do this, but it would need to be programmed for the desired voltage with a battery attached. After that , it can power resistive loads purely on PV without a battery.

Most MPPT require a battery to operate.

So a PWM be the better opinion for battery less? Interesting. Thanks for the input sir.

 

[v_green57]

Do you really need to "optimize" for a resistive load at all? Pure resistive loads make a straight-line current/voltage graph.

Put power to the elements. As long as you don't exceed their max. voltage, they get varying degrees of hot.

Simple.

The only thing you need to manage is max. temp of heated water. For that, as already discussed, there are DC thermostats and if necessary, relays or SSR's for handling bigger loads.

Pierre has the right idea - DC direct. Since I live close to SanTan and can get cheap used panels, I would use a dedicated array. But I don't use enough hot water to want to pursue it.

 

[efficientPV]

Trying to work out some water heating and was wondering if it's possible to connect PV to a SCC and connect the element to the battery side of the SCC. Of course controlled via DC thermostat. i was thinking that would maximize the power to the element as well as regulate amps and volts. Is that possible without involving a battery?

Thanks!

Yes, you can and it is a fairly simple technical problem. Once upon a time, solar was only the realm of technical individuals. Now it is open to everyone and that requires off the shelf products which are almost automatic to set up. What products are out there now for this purpose are quite expensive and even poor quality. A charge controller can not be connected to a heating element without a battery. I've been heating water for years and have worked out all the issues. There are dozens of ways to do it. They are all better and cheaper than the Rube Goldberg ways that people do it here. Just amazed there is no group of people here heating water efficiently. Below is a system that operates off the same panels a charge controller uses diverting only excess power without using charge controller, battery or inverter resources. Cost about $30.

 

[Danke]

Trying to work out some water heating and was wondering if it's possible to connect PV to a SCC and connect the element to the battery side of the SCC. Of course controlled via DC thermostat. i was thinking that would maximize the power to the element as well as regulate amps and volts. Is that possible without involving a battery?

Thanks!

What kind of system are you currently using? I know on my Sol-Ark I can use the Gen output for sub panel/water heater, etc. and only run my water heater when I have PV or battery at a specific state of charge window.

 

[McKravitts]

Although you can heat water with solar PV, and the above advice is excellent infiormation, it is far more efficient to do it with hot water solar panels.
Hot water panels vary in efficiency but on average only require about 1/4 or less of the surface area of PV panels to heat water.
If you, like most of us have limited space for panels, it is the best solution.

 

[Pierre]

Although you can heat water with solar PV, and the above advice is excellent infiormation, it is far more efficient to do it with hot water solar panels.
Hot water panels vary in efficiency but on average only require about 1/4 or less of the surface area of PV panels to heat water.
If you, like most of us have limited space for panels, it is the best solution.

You make a good point if you have the real estate to house these panels. Also they are single purpose i.e. only good for heating water. At least with solar pv you can use the power elsewhere when the water heater is on temp.

 

[Pierre]

Yes, you can and it is a fairly simple technical problem. Once upon a time, solar was only the realm of technical individuals. Now it is open to everyone and that requires off the shelf products which are almost automatic to set up. What products are out there now for this purpose are quite expensive and even poor quality. A charge controller can not be connected to a heating element without a battery. I've been heating water for years and have worked out all the issues. There are dozens of ways to do it. They are all better and cheaper than the Rube Goldberg ways that people do it here. Just amazed there is no group of people here heating water efficiently. Below is a system that operates off the same panels a charge controller uses diverting only excess power without using charge controller, battery or inverter resources. Cost about $30.
View attachment 183125

Care to share the circuit diagram please.

 

[Kiwi2000]

I'm happy enough just using PV to a decently large battery bank and then using a dedicated inverter (I'm only on 12v) to run my hot water cylinder with its standard 2kw AC element and thermostat. The reason being is that I can unplug it from the inverter and plug back into the grid whenever I want.

At first it was just a dump load from my system. Then I realized by increasing the size of the battery bank a bit, that I would be able to run the hot water cylinder 24/7 from my solar. And I can still plug it back into the grid should I need to. It's been working fine this way for months. And because it can keep heating the water during the night, it's not trying to heat colder water in the morning.

 

[sunsurfer]

One of these days, I want to setup some peltier based load diversions. Just to see what happens. The thing is, they are current driven more then voltage. You could have "some" cooling while also creating warm water or space heating. Likely though, I will build some sort of variable/frequency driven heat pump load diversion. Refrigeration is just so much more efficient.

 

[Whats-n-Watts]

What kind of system are you currently using? I know on my Sol-Ark I can use the Gen output for sub panel/water heater, etc. and only run my water heater when I have PV or battery at a specific state of charge window.

I haven't gotten any components other than a pallet of panels.

 

[Whats-n-Watts]

Do you really need to "optimize" for a resistive load at all? Pure resistive loads make a straight-line current/voltage graph.

Put power to the elements. As long as you don't exceed their max. voltage, they get varying degrees of hot.

Simple.

The only thing you need to manage is max. temp of heated water. For that, as already discussed, there are DC thermostats and if necessary, relays or SSR's for handling bigger loads.

Pierre has the right idea - DC direct. Since I live close to SanTan and can get cheap used panels, I would use a dedicated array. But I don't use enough hot water to want to pursue it.

I have read that directly connected does not utilize all the power the panel can produce due to amp rise / voltage lost as it will pull all the amps the panel can produce lowering voltage so I was hoping that would be possible with just a controller and a panel. Looks like not.

 

[Whats-n-Watts]

Yes, you can and it is a fairly simple technical problem. Once upon a time, solar was only the realm of technical individuals. Now it is open to everyone and that requires off the shelf products which are almost automatic to set up. What products are out there now for this purpose are quite expensive and even poor quality. A charge controller can not be connected to a heating element without a battery. I've been heating water for years and have worked out all the issues. There are dozens of ways to do it. They are all better and cheaper than the Rube Goldberg ways that people do it here. Just amazed there is no group of people here heating water efficiently. Below is a system that operates off the same panels a charge controller uses diverting only excess power without using charge controller, battery or inverter resources. Cost about $30.
View attachment 183125

How does that operate? Looks great.

 

[Whats-n-Watts]

I'm happy enough just using PV to a decently large battery bank and then using a dedicated inverter (I'm only on 12v) to run my hot water cylinder with its standard 2kw AC element and thermostat. The reason being is that I can unplug it from the inverter and plug back into the grid whenever I want.

At first it was just a dump load from my system. Then I realized by increasing the size of the battery bank a bit, that I would be able to run the hot water cylinder 24/7 from my solar. And I can still plug it back into the grid should I need to. It's been working fine this way for months. And because it can keep heating the water during the night, it's not trying to heat colder water in the morning.

I'm going dc with the heater so panel, battery and charge controller looks like the simplest answer for me.