Air heaters compatible with solar diverters

[Willbiker]

Hi All

Does anyone know what type of air heaters would be compatible with a solar diverter? I am about to install an Immersun diverter which will prioritise my hot water immersion heater however id like to add a secondary air heater. I take it only heaters without any chips/electronics are suitable due to the varying current?

I assume basic/cheap portable oil Radiators would be suitable but id prefer something on the wall.

Can anyone here share their experiences with using electric heaters with a solar setup without pulling from the grid?

Any suggestions?

Thanks!

 

[DThames]

What type of watt range are you talking about?

 

[Willbiker]

Hmmm my Solar system is not yet up and running so i'm not sure exactly what excess I will have but if my calculations are correct, I should have enough excess in the afternoon after my hot water tank is heated to run one or two 500w or 1kw heaters . However its my understanding that a diverter will send what ever power is available even if this is under the power rating of the heater? So if I install a 2kw heater and only 600w is available, the diverter sends the 600w to the heater? So in theory it shouldn't matter what size heater I install as only the available power will be sent to it. This is why a heater with no electronics and a mechanical thermostat is required, just like the immersion heater...am I wrong?

Thanks!

 

[DThames]

PTC heaters (in themselves) are self regulating.

12v example.
110v example.

I purchased one of these (no fins), put it between some bricks and did some power dumping tests with it. It gets hot

Remember, there is never "excess" there is only available. That means you have to develop a load to get the energy. It don't spill over into a "bucket" of sorts.

 

[SparkyJJO]

I'd assume the solar diverter has some way to limit the wattage either via voltage or current control. And yeah, that would require a non-electronic heater.

 

[DThames]

Hmmm my Solar system is not yet up and running so i'm not sure exactly what excess I will have but if my calculations are correct, I should have enough excess in the afternoon after my hot water tank is heated to run one or two 500w or 1kw heaters . However its my understanding that a diverter will send what ever power is available even if this is under the power rating of the heater? So if I install a 2kw heater and only 600w is available, the diverter sends the 600w to the heater? So in theory it shouldn't matter what size heater I install as only the available power will be sent to it. This is why a heater with no electronics and a mechanical thermostat is required, just like the immersion heater...am I wrong?

Thanks

I'd assume the solar diverter has some way to limit the wattage either via voltage or current control. And yeah, that would require a non-electronic heater.

Can't assume. The term "diverter" might be very loosely used in this case. The only way to put power from the panels to some other place is that other place must be a load. If you simply switch a 1000w load onto a panel array that can only deliver 500w (at current solar conditions) the 1000w load will pull the voltage down below the best power point and you will not even get your 500w. The load needs to be something close to what power is available right now, under these conditions.....or it needs to be small enough not to load the panels so much that you are getting very little from them. Having many small load devices and some smarts behind how many are turned on would be a diverter that did have a way to limit the load so that the power demanded from the panels is not more than the current conditions can support.

Power is not running wild trying to find a place to go. A load is needed to harvest power from the panels and the ideal load is changing with the solar conditions which change minute by minute unless you have a two axis tracker. I have however plugged in a DC heater load that was about 50% of the panels and just left it on. It makes heat and the voltage of the array stays above the Vmax point.

 

[efficientPV]

I've used oil filled heaters that have two elements in them. That gives you three options of resistance. Both in parallel gives about 400W @60V which is my array voltage. At 400W this is not touch safe. Should you want to operate with no safety switches it should be kept under that. If the room temperature much colder you can dump full power. I prefer options that don't use fans. That is a power point control diverter.

 

[Ampster]

Can anyone here share their experiences with using electric heaters with a solar setup without pulling from the grid?

Any suggestions?

I used air source heat pumps and heat pump water heaters because they are much more efficient than resistive heat. They are more expensive but long-term more cost effective.

 

[Willbiker]

Can't assume. The term "diverter" might be very loosely used in this case. The only way to put power from the panels to some other place is that other place must be a load. If you simply switch a 1000w load onto a panel array that can only deliver 500w (at current solar conditions) the 1000w load will pull the voltage down below the best power point and you will not even get your 500w. The load needs to be something close to what power is available right now, under these conditions.....or it needs to be small enough not to load the panels so much that you are getting very little from them. Having many small load devices and some smarts behind how many are turned on would be a diverter that did have a way to limit the load so that the power demanded from the panels is not more than the current conditions can support.

Power is not running wild trying to find a place to go. A load is needed to harvest power from the panels and the ideal load is changing with the solar conditions which change minute by minute unless you have a two axis tracker. I have however plugged in a DC heater load that was about 50% of the panels and just left it on. It makes heat and the voltage of the array stays above the Vmax point.

Thanks for the info and I see your point. Most examples of people using solar diverters, AC not DC, in residential installs that I have seen have a 3kw 230v immersion heater connected and it may draw 3kw however the diverter seems to supply what ever is available, be it 500w or 3000w. This seems to be the norm with these devices... I assumed an air heating device with no electronics could operate in the same way. maybe I've misunderstood how these devices work...

 

[efficientPV]

More than that, almost all divert from a battery. I divert from PV array voltage and just what is excess. That allows me to over panel and not need a big charge controller, battery or inverter. Diversion is just what is excess no matter how small or how short the excess lasts and instantly respond to sun conditions. I looked at a heat pump and it would require me spending $2,000 more than the heat pump itself. Here is the diversion from just a half hour of constant on off

 

[Willbiker]

here is an example of a similar Diverter, if you jump to 1 min 40 seconds you can see even though the load is a 2kw kettle, only 700w if being supplied as that is all that is available

Can I not replicate this but with a air heater instead?

 

[RaidenPatel]

I tried to put a similar system in my home. Still, when I called my friend, who knows a lot about it, he told me that such systems are too complicated to install and connect and do not produce the necessary amount of energy, which is not energy efficient. He advised me to put a conventional power system. That's what he said when I asked him about warehouse heating in my transport company. He told me to go to a firm that heats industrial warehouses, and they will prove my idea's inefficiency. And after consulting with specialists from this company, I realized that the idea was losing and unprofitable.