Solar MPPT Controller

[camilo]

Have any of you used this ? They sell it online... I've seen youtube videos about it. I actually just purchased one and am waiting for it to get to me to test. Wondering if any of you have experience with it? Not sure if I should be posting links but you can find it on youtube under "Solar Hybrid Hot Water Controller".

Curious to hear responses on this.

[camilo]

Here's a pic of it

[Mike90250]

if you could post a link to the mfg's site (not a vendors sales site) we could tell you a bit more. Smells like a scam to me though.

[camilo]

http://techluck.com/

[PNPmacnab]

There is not much out there at a reasonable price. I think the unit has some technical issues and performance is not as good as they quote. Still, it is better than just connecting panels directly to a heater element. Certainly would like to test one. They want people to think it is UL approved just because it is put in a UL box.

[Mike90250]

It's a KIT. you buy a circuit board with unknown engineering quality, you heat sink it, and put it in a box. Now the company has no liabilities if your house burns down, but the NEMA box should contain any flames.
Clever idea, no efficiency specs.

[J.P.M.]

if you could post a link to the mfg's site (not a vendors sales site) we could tell you a bit more. Smells like a scam to me though.

big +1 on the scam aspect. I'd not use it. The vendor's site is mostly B.S./hype. Big caveat emptor on this P.O.S.

[camilo]

will be sure to let you guys know if it works once I have it on my hands.

[J.P.M.]

will be sure to let you guys know if it works once I have it on my hands.

It may work for awhile, but if something bad happens, it may not happen on startup. Either or any way, depending on when and what happens, you may not be around to advise how it's working out for you.

[PNPmacnab]

Aside from the boogie man will get you and the world will end as we know it. I have been heating water at my camp for years by a similar method. The same basic principals which are used in any switch mode power supply. In electronics there are always a half dozen ways to do something with slightly varying results. This product uses an IGBT in the output which means being stuck with about 15W heat loss. I use low on resistance FET and you can barely sense any temp rise. Techluc uses off periods to quench an arc when mechanical temp contacts are used. These would have to be 1-2ms in length about every 15ms. Their caps do not be sufficient to store that energy or do I suspect longevity. I suspect at lower light levels it is less efficient than stated. Unless you want to build one yourself from plans out there, this is what is available. Other quality units are considerably more expensive. I use mine to harvest excess energy that has no place to go and would normally be just wasted.

Just how much panel power are you expecting to put into this and at what voltage?

[bcroe]

Guessing its a buck converter with an MPPT feedback. With no shielding or RF filters, will
kill radio reception nearby. $300 is a lot for a barefoot system of that power level, I think a
lot of switchers of that size are going for a tiny fraction of that. Must be a coil (choke) in there
to actually do MPPT (never seen it done with switched caps).

Would be fun to get a scope on it. good luck, Bruce Roe

[PNPmacnab]

No, it is a PWM IGBT switch from a small capacitor bank. It likely has a dual PWM with a fixed off time at about line frequency and the potential on time is PWMed at about 400-800Hz due to the small capacitor bank. Lacking a high speed driver, the on/off transitions are relatively slow in the world of switching and don't produce much noise. I PWM at 120Hz and you have to lay an AM redio right on the wire to pick up anything. PV water heating is popular in Europe and Australia where these devices drive a water heater element with a H bridge for far better arc suppression since polarity reverses. This is a modified sine wave with adjustable duty cycle. Curious about the MPPT. It might be it measures peak voltage at arc preventing off time and sets the target voltage at 75% 0f that. The designer doesn't appear to be that sophisticated. I'd sure like to scope it.

The simplest explanation of operation is during off times the capacitor bank charges, say 5A that panel can provide. In the on cycle you get the panel 5A and the capacitor bank 5A for 10A of current till the voltage drops and it turns off.

[bcroe]

No, it is a PWM IGBT switch from a small capacitor bank. It likely has a dual PWM with a fixed off time at about line frequency and the potential on time is PWMed at about 400-800Hz due to the small capacitor bank. Lacking a high speed driver, the on/off transitions are relatively slow in the world of switching and don't produce much noise. I PWM at 120Hz and you have to lay an AM redio right on the wire to pick up anything. PV water heating is popular in Europe and Australia where these devices drive a water heater element with a H bridge for far better arc suppression since polarity reverses. This is a modified sine wave with adjustable duty cycle. Curious about the MPPT. It might be it measures peak voltage at arc preventing off time and sets the target voltage at 75% 0f that. The designer doesn't appear to be that sophisticated. I'd sure like to scope it.

The simplest explanation of operation is during off times the capacitor bank charges, say 5A that panel can provide. In the on cycle you get the panel 5A and the capacitor bank 5A for 10A of current till the voltage drops and it turns off.

The ad claims it is MPPT, they lied? Yes the H bridge is a good approach so your thermostat has a
chance of doing its job, and with chokes some voltage/current conversion could be done at the same
time for MPPT. It takes more than simple switches. Is it worth the price?

Every situation is different, but the first digital ckts I built half a century ago were radio killers. I have
become proficient at shielding and filtering, as an inspection of my inventory would reveal. Bruce Roe

[camilo]

Aside from the boogie man will get you and the world will end as we know it. I have been heating water at my camp for years by a similar method. The same basic principals which are used in any switch mode power supply. In electronics there are always a half dozen ways to do something with slightly varying results. This product uses an IGBT in the output which means being stuck with about 15W heat loss. I use low on resistance FET and you can barely sense any temp rise. Techluc uses off periods to quench an arc when mechanical temp contacts are used. These would have to be 1-2ms in length about every 15ms. Their caps do not be sufficient to store that energy or do I suspect longevity. I suspect at lower light levels it is less efficient than stated. Unless you want to build one yourself from plans out there, this is what is available. Other quality units are considerably more expensive. I use mine to harvest excess energy that has no place to go and would normally be just wasted.

Just how much panel power are you expecting to put into this and at what voltage?

Thanks for the reply!

A little backstory. I have (4) Hyundai 255 watt panels on my carport roof that were connected to SunBandit microinverters, going down to a SunBandit water heater. Have you heard of those systems (SunBandit) ? Well, the SunBandit microinverters fried and they are out of warranty, and a new one would cost somewhere around $1400.

Figured i'd buy this $300 piece and try it out. The SunBandit has 3000W elements and thermostats on the Solar side, and they're completely separate from the Grid element. My thought was to start with 1 panel, moving on to 2, and maxing out at 3, wired in series. I know that it wouldn't be a good idea to hook all 4 to this thing, 3 might be questionable as well (even buying a bigger metal box to put it in), so all in all i'm curious at how well it will work. If it works, i'll have to find another use for the leftover panels.

Worst come worst i'll simply buy another SunBandit micro and call it a day.

The panel specs are -
255 watt
VMPP - 30.8 V
IMPP - 8.3 A
VOC - 37.7 V
ISC - 8.8 A