2015
Review Techluck
I was going to ask you if you have seen or heard anything about the PV solar controller sold at ...

http://techluck.com/

I have been doing solar as a hobby for 15+ years now and in the time the prices have dropped from 5$ or more/watt to less than 1$/watt.
In doing so there have been a whole lot of technologies and components that have gone by the way side or relegated to niche applications:
Examples:
   Thin flim solar
   Active and Passive trackers mounts
   Top of pole mounts

In your opinion, are thermal solar water heater systems, especially the ones that require glycol due to freezing conditions also going to be added to this list?
There are special exchange type water heaters that are needed for thermal water heat systems.  PV power can be transported longer distance with less loss and can use a standard resistive element water heater.   The problem with using PV is the thermostats (the contacts) will burn out fast if fed DC.   Requiring a special DC->AC controller.

  -Dave
Another followup
http://techluck.com/

This guy sent his idea for me to assess.

We disagreed, and he stopped emailing.
Inventors are very headstrong... which make them good inventors

I am hyper critical about detail, which makes me a pain in the ass.
I was critical of his initial wiring setup, his sales presentation, and his claim of heating
(No doubt he cleaned up his wiring since he seemed knowledgeable, and his sales presentation seems very nice).

He believes in his invention.
Probably the converter is well-made from off-the shelf parts... but he would never send close-up photo for fear of losing his invention.

Heating... I am skeptical...
He claimed two solar panels heat lower part of his tank during day.
Of course I do not have test facilities, or live in California where he does.
He showed me the output numbers
I forget exact Kw he gave.

It was very low Kw arriving from 2 solar panels.

I told him the Kw required to effectively heat water exceeded the solar output he showed.
Memory recalls the amount of Kw would heat 1-2 gallon in several hours.
So there would be some benefit.
I remembered a bit more since yesterday.

The problem with the techluck wiring was connection to water heater.

Water heater warranty:
Of course any connection that alters original wiring voids water heater warranty.

No way to connect wires to bottom element:
His wires from the converter were tied into the water heater without any box or covering.
His wires, and element and themostat were exposed to open air.
I suppose you would have to drill through the side, or run wire under the bottom cover.

Code:
His wires from top part of tank were in open view with wire nuts after being disconnected from thermostat.
Electric code requires these wires removed from same cavity as wires arriving from different power source.

NO ECO? Energy cut-off. (red reset button)
-Either he wired directly to the element.... and bypassed thermostat... which means the lower part of tank had no energy cut off.
-Or he wired to the lower thermostat... which has no energy cut-off.

Bad science?
His thermostat was exposed to open air and not covered with insulation
If he wired to the thermostat.... then it shows there is no substantial heating.
This is because water heater thermostat must be covered with insulation to correctly read water temperature through tank wall.
Ordinary water heater thermostat exposed to cool room air temperature will misread water temperature and cause run-away heating.
Obviously there was no run-away heating, or his TP valve would release water.

Maybe good way to use his invention:
Connect at top of single-element 10-20 gallon tank.

I totally agree Gene.  Using techluck in a single water heater setup it violates code + warranty and bypasses many of the safety mechanisms (ECO, thermostat misread, wires modified, UL listing gone due to mods).   The idea has merit but it requires two tanks at minimum.  Cold water goes into Solar pre-heat tank with the techluck and one after on normal grid power.

I hit the same issue with my solar controller.  Originally I was going to modify the wiring to make it simultaneous but hit a brick wall when I could not put an ECO + thermo on the bottom element.
Unlike the severely limited output of the techluck, my system DOES have the power to easily over heat the tank in the case the thermo sticks closed.

So I left the wiring internally stock (except for the 1-wire remote temp readers). 

I agree that DC power burns out thermostats quickly the same way it burns up normal power relays when they are fed DC power instead of the AC power they are rated at.   Relays can be delicate.

 I had an issue with relays in my controller box getting destroyed when I switched elements between 240VAC and 120VAC. I solved the issue by turning off the power relay (DPST relay) feeding the 120/240 selection relay (SPDT relay), then flipping 120/240 relay state, then turning the power relay back on.   I figured the arc flash betwen the N and Hot side of the DPST relay was being aided and abetted by the armature moving between contacts while under power. 

The big problem I see with the techluck is that the max PV you can put into is like 1250 watts PV nameplate rating and even then he very much cautions that the user should not overdrive the controller.  I suspect that it does not last long at its max rated wattage.  Recommending like 750 is a good number to hit so it doesn't burn out before the warranty period is over.

Problem is I typically burn through 10-15Kw of hot water on a daily basis.  A 1250 watts max setup at a average 6 hours (Im being generous) direct sun equivalent is only 7.5Kw yeild.    Derate that by non-ideal solar conditions and a more sustainable 750watt array and now its only about a quarter of my needs.

So just need another techluck controller and a second PV array right?  Not so fast.  The controller inverts the DC from the panels into an AC waveform.  The AC waveform from two controllers will not be in phase sync and if the outputs are connected together they will probably fry each other like connecting a genny output to the grid.  

So more yeild requires a separate water heater for each controller or hack to make the water heater unsafe as you have stated and feeding top and bottom with separate techluck.

So techluck is a niche product.  Someone that likes the idea of solar and wants a system to marginally assist in water heating.  It does not provide any other facility to make usable power for any of the few zillion electrical devices in my house.
    We disagreed, and he stopped emailing.
    Inventors are very headstrong... which make them good inventors


I wouldn't classify myself as an inventor but I do "invent" things from time to time.  Im more of a builder / system integrator.  I like running systems, open to whatever comes along.  I do notice trends a lot when it comes to technology. 

I see tech diverging recently.   On the one hand there is tech for stupid people (Google Nest thermostat are now selling in Home Depot).  And on the other hand there are more SOC system-on-a-chip like the Arduino and Raspberry Pi ($35) that allow people to run their own custom gear that is not cloud-based.   The data need never leave the confines of the local area network.

    I am hyper critical about detail, which makes me a pain in the ass.
    I was critical of his initial wiring setup, his sales presentation, and his claim of heating
    (No doubt he cleaned up his wiring since he seemed knowledgeable, and his sales presentation seems very nice).


My take is when it comes to electrical and plumbing.  Code is code.  Its that way for a reason.    Water heaters have blown up peoples houses and that's why they are built with triple safeties (thermo -> ECO -> T&P).
As example, code is no threads on the T&P pipe, not because smart people will cap off the T&P but because stupid people might.     Techluck guy needs more emphasis  on his website on how to install his gear and do it so its safe and preferably to code.

    He believes in his invention.
    Probably the converter is well-made from off-the shelf parts... but he would never send close-up photo for fear of losing his invention.


Probably a custom board but I haven't seen it in person. Buddy at work might buy one and I will get to see it up close.  Apparently its easy to have PCB boards printed, populated and soldered these days.  Just need the volume to make it cheap.

    Heating... I am skeptical...
    He claimed two solar panels heat lower part of his tank during day.
    Of course I do not have test facilities, or live in California where he does.
    He showed me the output numbers
    I forget exact Kw he gave.

    It was very low Kw arriving from 2 solar panels.

    I told him the Kw required to effectively heat water exceeded the solar output he showed.
    Memory recalls the amount of Kw would heat 1-2 gallon in several hours.
    So there would be some benefit.


The idea has merit but realistically it needs the ability to handle more power like 2x or 3x as much.   Needs to be more honest about having a second tank.   Buddy at work has got lots of space for a second tank to go along side is newly refurbished 50 gallon electric Bradford White.    He used the trick off your site to vacuum out the crud at the bottom after his bottom element went boom.  

He is thinking using the 105 marathon as the primary grid powered and the 50 gallon using a techluck preheat.    Im interested to see how the whole thing will work.

Whats the deal with fused upper elements???   Do I really need them if I am smart enough to never dry fire the upper element.   Seems to me its just another part to fail.

-Dave
Let me know what you discover about techluck... if you can invent or prove a useful product, I will display it on my website in detail.
... make you into a thousandaire
LOL.   Ill take you up on that. :)   I could use a couple thousand bucks.

I think the big problem is that a techluck style system that inverts DC->AC waveform with a decent level of power (3 to 4 kW of PV solar) will cost a lot of money.   My inverters that I run are rated at 3600W continuous and cost around 1700$ each.   Im sure his gear isn't nearly as beefy as my outbacks so it needs to be limited to 750watts for long lifetime.    And what is more the whole DC->AC thing is really not needed because DC elements can heat water just fine.  The issue is the thermostats and the ECOs burning out with DC power.    Its possible to buy standard fitting DC powered water heater elements that run on 48VDC but they are a specialty item and they have low wattage.  They are also really pricey.

The whole idea of lets just use standard elements and drive the water heater with high voltage (120 to 240 VDC) power does have merit.   PV is cheap.  Standard electric water heaters with standard elements are cheap.  The trick is the power control to not burn the delicate AC rated relay/switches inside the ECO and thermos.

Here is an idea:   I know it removes the UL listing because it mods the UL listed water heater but consider:

Have a small 120 or 240 AC power source.  Feed the water heater with it so that the ECO/Thermo  receive the 120 or 240 VAC that they want but then use the 120 or 240VAC supplied at the bottom of the thermostats to drive a 120 or 240VAC coil relay(s) with *DC* rated contacts so its possible to switch the PV DC on and off and feed that to the water heater elements.  

For a typical water heater with two elements.  Two relays will be required.  One to switch the upper and one to switch the lower.

End result:  The ECO and thermos that come stock standard with the water heater are not themselves modified (just their wiring).   They are never exposed to DC and therefore not driven by power they were not speced for.    The DC is switched by a device that is UL rated to handle that power.

There is no fancy shmancy controller that inverts the wave form that is power limited to 1250Watts.  There is no loss of efficiency in converting the DC -> AC.  

Techluck really needs two water heaters. 
Now we go to the solar idea.. and hot to wire it