PV opportunity hot water heating

[Volvo Farmer]

Oooh, interesting. My batteries are also 100+ ft from the house.  How are you triggering those SSRs Ryan? Would cat5 cable work at those distances? I have often thought a wireless solution would be rather elegant as pulling another cable through conduit and getting it to the proper place would be a pain, as the sheet rock is already hung.

[Halfcrazy]

Yes I am using Cat5 cable. We are working on an addition that may just take care of the wireless ideas?

Ryan

[zoneblue]

No newer manual.  OK, swap those words "Opportunity" with "Waste Not".
Thank you for pointing out this error in the manual !!

No worries! But could you please explain how 'Waste not Hi' works.

The name suggests that the pwm output is somehow proportional to the percentage of the array's output that the controller considers 'waste'. Is that right?  Or is it proportional to the absolute amount of kilowatts considered waste, or put another way the percentage of the controllers possible output ?  That would be easier to match with the opportunity load.

Are the pulse freq and peak voltage constant, but the duty cycle modulated? Or is the pulse width constant and the frequency variable?

[zoneblue]

Ok Rereading the manual:

"There is also a voltage "width" adjustment, the voltage width being the range where the PWM goes
from a short pulse, beginning right at the charge set point voltage, and full on at the diversion set point
voltage "plus" the width voltage" p30.

So do you just adjust it by trial and error?

[dgd]

I wish I had some good information for ya,

But something strikes me as seriously wrong with the universe if it makes sense to
convert sunlight into electricity to drive resistive loads to heat water.

seriously.

Actually it's very satisfying to use sunlight to make electricity to heat water. Remember all our energy originates from the sun, all the energy in fossil fuels, wind, water flow etc..
Its a Much more direct use of energy too , not involving chemical reactions, pollution, by products etc.
The universe is in order, the answer is still 42
Dgd

[Volvo Farmer]

Yes I am using Cat5 cable. We are working on an addition that may just take care of the wireless ideas?

Ryan

Really? Cool! 
My dream would be to have a black box that plugged into the Classics aux function and sent a wireless signal to another black box a couple hundred feet away. The receiving box would plug into a wall outlet and have a 15A rating so I could run whatever type of opportunity load off the inverter that I chose to plug into it.  Ideally, the receiver would have minimal power draw and the transmitter would only wake up when the aux function goes high, minimizing the idle current for the whole device.

You asked! 

[Eric L]

My dream would be to have a black box that plugged into the Classics aux function and sent a wireless signal to another black box a couple hundred feet away.

Not as elegant as that, but it wasn't hard for me to run Cat 5 cable under the house and into rooms using unused old coax tv cable outlets. I used the old coax to pull the Cat 5 through the walls. This lets me get a signal in from my Classics to turn on other opportunity loads like room air-conditioners in summer and oil-filled space heaters in the winter.

[SolarMusher]

Another option (and more efficient use of PV power) is to use a heat pump water heater such as the Nyle Geyser.  I have one and it works great. Draws about 600-800 watts when running.  When running in my basement with air temp of 55 Degrees F it will take my cold water (50F ?) and heat 50 gallons to 125F in about 3-4 hours.

Hi mtdoc,
I would like to try to run a Nyle Geyser water heater on a secondary tank, on Aux when Absorbing. Could you tell me if you control this water heater from Aux with SSR or if you run it directly from your inverter without control? Is Waste not the best Aux mode to do that? I don't think that I need PWM Aux as this heater just draws only 5/7 amps on 120Vac.
Could I use a simple SSR 120V 25A as a switch? Do you think I need a heatsink?
Thanks,
Erik

[mtdoc]

Erik,

When the grid is down for me,  the Nyle Geyser runs from the inverter directly just as any other load. I don't use the Classics Aux function.  It draws about 600-800 watts when running.

I could be wrong but I don't think that using the Aux mode/Waste not Hi/SSR  method would work well with a heat pump type water heater like the Geyser.   The heat pumps method of heating water is inherently different than the traditional resistive heating element type of water heating and I don't think it would be likely to respond well to a rapid on/off PWM type AC input.   I haven't tried it so perhaps I'm wrong  - maybe other's know more and can comment.

I'm sure there is probably a good solution for using one of the Classics other -non PWM - Aux functions to turn on a SSR allowing power to a heat pump water heater when batteries are in absorb or float -but I haven't investigated this.  Others can probably tell you more..

Good luck - I'll look forward to hearing what you end up doing since eventually I'd like to set my Geyser up to do the same during extended power outages....

[SolarMusher]

Allo mt,
I was thinking I could use Aux1 opportunity hi (not PWM) or Float to switch a SSR on Abs voltage and power a Geyser-RO with its own temp control in the same way I use Vent Fan High on Aux1 to power a 48V fan on batteries with a 12V relay. Of course I could be wrong, I have send a request to Nyle to see what they'll say. I will post their answer. Right now I don't see a problem except that I need to move toilet to have enough place to add a secondary tank 
What was the price of your Geyser?
Do you like it?
Erik

[Westbranch]

Just a passing thought:  why not use the 'cooling' from the Nyle to cool the battery enclosure? the Batts might like to be cooler than ambient temp... rather than just cool the whole basement?

[SolarMusher]

Good idea West but at this time my batts are somewhere in the 7/13°C range, inside... So a little cold to me.
My old 40 gal gas heater tank had failed in December and I had to change it very quickly for a 30 gal. This would be the time to upgrade to a more efficient heating system using this old storage tank and the Nyle's Geyser would be a great/smooth update with it's little 5/7 amps. I'm pretty sure that I could run it without problems for 3-4 hours from March to September from my 3.2Kw PV on Absorb/Float, this could save me a ton of propane in summer. I rent this off-grid lodge for fishing time with showers x8-10/day. I've also read Eric and Chris posts and found it interesting but I would need to buy another electric water heater and I'm not sure my system could take it.
Erik

[Westbranch]

this could save me a ton of propane in summer. I rent this off-grid lodge for fishing time with showers x8-10/day. I've also read Eric and Chris posts and found it interesting but I would need to buy another electric water heater and I'm not sure my system could take it.
Erik

since we are likely talking Opportunity loads maybe time for a few more (dedicated?) panels for those cabin loads? or is your CC maxed out?

[mtdoc]

Erik,

I bought the Geyser direct from Nyle systems  - since there is no dealer near me. I can't remember exactly what I paid - I think it was something like 10% off their list price - around $700 if I recall correctly.

I've been very happy with it. It seems very well made and the installation was easy. I also bought the RO version which has a Johnson Controls thermostat - control unit on it.  This makes it very flexible for different installs.

Your plan for using the opportunity Hi Aux function sounds good.  I'll look forward to hearing how that works for you.

[SolarMusher]

since we are likely talking Opportunity loads maybe time for a few more (dedicated?) panels for those cabin loads? or is your CC maxed out?

Ha, Ha, good catch, West. I'm 106.7Vmp, 30.54Imp input. So my Classic 200 outputs a 54/55Amps @59.2Vdc, but I've reached 60A several times this winter. I could still add 3 or 6 more cheap 185W panels to reach 4.3Kw and limit the output at 65/68A max to not overcharge the Classic, maybe I could find a little free place on roof...
But for now, I have to give priority to the heater

Erik,
I bought the Geyser direct from Nyle systems  - since there is no dealer near me. I can't remember exactly what I paid - I think it was something like 10% off their list price - around $700 if I recall correctly.
I've been very happy with it. It seems very well made and the installation was easy. I also bought the RO version which has a Johnson Controls thermostat - control unit on it.  This makes it very flexible for different installs.
Your plan for using the opportunity Hi Aux function sounds good.  I'll look forward to hearing how that works for you.

Thanks mt for the infos.
Great to hear that you're happy with your Geyser and that it's working the way you want.
I've sent an E-mail to Nyle and explained exactly how I would like to use it. I would like to have it installed and running before spring.
Thanks for your help,
Erik