Pairing up the Eco-worthy 20a MPPT controller

[JiminDenver]

Thanks to BFL confirming that the Eco-Worthy controller plays well when run with another controller, I felt pretty good about combining my two matched controllers. Each had one of the Bosch 245w mono panels aimed not perfect but good enough considering that they will be flat mounted. I used a fully charged 95 ah grp 27 so that I could move the voltage easier than the 8-D.

I used the inverter and a 1875w hair dryer as a load. I tried high but the voltage dropped so fast that the inverter shut off before I could check either the controllers or the meter on the battery. After shutting off the inverter the controllers put out a combined 28-30 amps until it hit float.

After it had been in float a bit I tried the low setting on the hair dryer. This time the batteries voltage only dropped to 12.3v and both controllers were putting out 13a average. I knew they were good for more so I disconnected one of the panels and the other controller shot up near 16a. This let the battery drop in voltage and when I plugged in the other panel, both systems ran close to 16a. They stayed that way until I shut off the hair dryer and inverter and let the battery come up.

I did find that I could use the high setting for short times if I started in low and let the controllers get ramped up. They were putting out 13a each until I hit high, then they jumped up above 16a each. The voltage did drop but slower this time. With the help of the solar, the hair dryer ran a minute before the inverters alarm went off.

I did get a chance to see the Mono panels with on and off clouds. Any significant clouding and the output dropped to 2.5a for each panel even if I was running a load. I didn't pull out the 230w poly but I've seen it do 3-4a in lower light. Just shutting down the inverter would save more amps than I'm losing, it's a real pig.

So I'm pretty happy with the combined systems. I'll probably see higher amps up at altitude but only if I'm running the microwave at high noon. With this in mind, I may go with the Rogue 30a instead of the Morningstar 45a for mounting and save the money. Clipping may not be a issue often and it would only be a few amps at peak hours.

Last thing is about the absorb cycle on the Eco-worthys. Even if I set the absorb at 15v, it didn't last. The controller would come out of bulk, switch to absorb and raise the voltage to the set point. As soon as it hit that the controllers dropped to float. I will say that 32a pushes a grp 27 around pretty easy. Next test it will be the 8-D, it doesn't push so easy.

[JiminDenver]

BFL13 wrote:
Thanks 12thgen, so that solves that mystery. Jim figured it right by reading up on it like that. Hope he didn't hurt himself! 🙂

Now don't go expecting the reading thing often. I almost had to go get more aspirin TWICE!

[JiminDenver]

So all this time MPPT has been getting the credit when the real star of the show is the buck converter. It is good to know that the system is not limited to the panels Isc outside of bulk.

[BFL13]

Thanks 12thgen, so that solves that mystery. Jim figured it right by reading up on it like that. Hope he didn't hurt himself! 🙂

[12thgenusa]

The MPPT and DC to DC converter are separate functions of the controller. MPPT only functions in bulk mode. The DC to DC converter is always active. As such panel Isc has no real meaning in relation to panel output. I'm afraid it is now the "dreaded" watts that determine output. Amps are proportional to watts with respect to battery voltage.

The rated Isc for my panels in parallel is 10.2 yet at full power I can see north of 25 amps output. If the batteries are full the controller will produce greater than 12 amps with external loads in float before moving back to bulk.

[BFL13]

JiminDenver wrote:
So a simple test if one of us gets the time to prove that the extra amps from the buck converter are always available even in float.

Have the 230w panel set up with the battery in float. Put a load on the system and slowly increase it but not so fast or high that it brings the batteries voltage below float and takes the charger into MPPT mode.

If the theory is correct, 230w/13.6v = 16.9a not accounting for loses and inefficiency. With the right load you could see 16a in float. I know I've seen over 13a in float and over 16a in bulk. If you can tweak the load to that point with out kicking the controller into bulk, it means that MPPT doesn't create extra amps at all, the converter does. MPPT just controls what volts and amps are needed to best charge the battery the fastest.

On low voltage systems there is still enough excess voltage to see some conversion at the converter and the program can then decide how to best use it in bulk.

Not too sure this is what you wanted but:

Trimetric says 14.3v, 4.1a (which is pretty much all to the battery) and we are down minus 7.39AH (so nearly full out of 458)

Eco-W readout says: Float, 14.4v, 5.22a, 75W (out of 230w panel)

Demo says PWM is 8.02a (Panel Isc rated 8.3a) Time is 4PM with sun lower than at noon of course, explaining why Isc is less than rated, panel in contraption more or less aimed. Demo MPPT is 12.75a (but we are in Float) at 59% efficient.

Turned on some loads:

Trimetric says 14.3v, 4.0a, -7.26AH (Tri only shows battery amps)

Eco-W says Float, 14.4v, 11.3a, 161w

Demo says PWM 8.07a, 12.95a MPPT (but amps are 11.3 in Float)

So the solar is picking up the load with the extra amps, well above panel Isc rating, and the batts are still getting the same 4a as without the load. (So load was about 7.3a.)

[JiminDenver]

So a simple test if one of us gets the time to prove that the extra amps from the buck converter are always available even in float.

Have the 230w panel set up with the battery in float. Put a load on the system and slowly increase it but not so fast or high that it brings the batteries voltage below float and takes the charger into MPPT mode.

If the theory is correct, 230w/13.6v = 16.9a not accounting for loses and inefficiency. With the right load you could see 16a in float. I know I've seen over 13a in float and over 16a in bulk. If you can tweak the load to that point with out kicking the controller into bulk, it means that MPPT doesn't create extra amps at all, the converter does. MPPT just controls what volts and amps are needed to best charge the battery the fastest.

On low voltage systems there is still enough excess voltage to see some conversion at the converter and the program can then decide how to best use it in bulk.

[JiminDenver]

So I've been reading. Don't be afraid, I am enough for both of us. 😉

A buck converter is a DC to AC to DC converter. MPPT samples the array and the battery and tells the converter what the maximum output should be or tunes the system for best results.

So unless the Eco-w is shutting down the buck converter and switching to a second PWM system, the buck converter is still taking taking in higher volts at low amps and putting out lower volts with higher amps. It is just not tuned any longer because the charging is already tapered and max result are not needed.

To go any deeper requires formulas and other headache causing info.

[JiminDenver]

One thing I know is the Eco-w's are getting more popular. I use to see the auctions with free shipping end in the $70 range. The last two I won were $85 and now I rarely see them ending below $90 with some being more than ordering off of the website. There is a auction ending at midnight that is already above $90 and they have been only running one auction at a time. The rest are Buy it now and more than the website.

I wish there was a 30 or 40a version, it would be worth a few bucks to have some more features too.

[BFL13]

I would not know what is what on the circuit board.

My observation on the demo was that the PWM amps they use just happen to be the same as what the panel Isc was at the time, at different amounts at different times. Sometimes Isc is above rated. I did note that when the 230w was above its Isc, so was the 130, which means it is an insolation thing at the time, not something the controller was doing.

Jim may be onto something about what happens after Bulk and you still get more than Isc (where Isc is not over its rating at the time). Can you still do the "buck" and just not do any power point tracking?

Other MPPT controllers also drop out of MPPT and go PWM after Bulk. Do they get higher than panel Isc too after dropping out of MPPT?

[JiminDenver]

BFL

I've been thinking about the PWM amps in float and the demo mode.

The Eco-w uses a buck converter to take the excess voltage down to a usable level, creating extra amps as it does. I don't think it needs the MPPT function to do this outside of bulk mode where you need as much power as possible. Those extra amps may always be there, it's just the controller rarely calls for that level of power in float. So we may be seeing 13a in float but add in the MPPT function and you get another 3 amps from the maximization of the power point. (whatever that means)

I played with the demo mode in the beginning and thought it was a gimmick because it was saying the panel was above it's rated output. Since then I have seen the Isc well above the rating so I'm not sure how it's done. I thought it was a calculation and looking at the guts of the controller I shorted, I wouldn't know what to look for honestly. There is a wire about a inch or so that is covered with a loose clear sleeve. Could that be a shunt of some sort?

[BFL13]

mena661 wrote:

BFL13 wrote:
So after all that we are back to where we were three years ago when I found out that 210w was perfect for us. Got to stop fixing things that ain't broke!

Always wondered why you switched from that setup.

Money. In 2011 started with an 80w ($350) and a 130w ($450) and the 210w was perfect for us. Then I learned prices were dropping and wished I had not bought the 80. Lucky for me the dealer took it back so I had just the 130.

In 2012 I tried the 130 in the floppy type contraption and that was almost enough solar. But then I found the guy here who was selling panels for $1.20 a watt so I got a 120w and now was back to 250w. Perfect again. That is where I should have stayed.

But then this guy dropped to 1.08 a watt and would take back the 120 I just bought so I got two 100s. That was my 2013 set of 330w which was too much solar. I didn't want to sell the 130 and take a bath on that, but a camper here wanted my two 100s so I sold them and was back to 130. I was going to get a 120 at $1.08 but the dealer went out of business before I could.

Then last Fall I saw that the dealer who sold me the panels in 2011 was now selling 230w panels for $275 and Jim found the Eco-W for $102 so I did that. Now I had 360w! Way too much. However now time has passed I don't feel so bad taking a bath on the 130w (three years old) (which she is now selling new for $260 instead of $450 back then.)

So I just sold the 130 and some Vector chargers I no longer need to a camper who needs them and am not out too much, and here I am---your new MPPT man!

Now I need to find a likely newbie who will take the 230 and Eco-W for say $375 and now the other dealer is back in business, I could get two 120s for say $300 and use the Solar30 I kept. Then I would be a proper civilized PWM man again with a perfect 240w set. 🙂

Maybe I should just get a table at the Flea Market and buy and sell solar stuff ?

[mena661]

JiminDenver wrote:

Even when BFL finally caved in to his desires and bought his precious MPPT, he tried to hide it from us by claiming it was ONLY for comparative testing as he was going to prove once and for all......but look at him now. He is beaten. The MPPT has completely taken over and any remaining shred of PWM dignity has been ripped away. He will forever giddily collect his extra amps wondering if those poor people using PWM knew what was just beyond their grasp.

OR, like me, likes to buy new toys and play with them. 🙂

LMAO! That poor bastard.

[JiminDenver]

😉

[BFL13]

I am forced to admit it is truly wonderful to be getting 15.5 amps with MPPT instead of a mere 14.5 amps with PWM at noon. Why, that comes to a whole extra 7 AH a day if it stays that much above PWM for seven hours of the day.

Imagine all the fun you can have with those extra 7 AH a day! I am so excited I could just -----. 🙂

[KJINTF]

Sure got a good laugh from this

"Even when BFL finally caved in to his desires and bought his precious MPPT, he tried to hide it from us by claiming it was ONLY for comparative testing as he was going to prove once and for all......but look at him now. He is beaten. The MPPT has completely taken over and any remaining shred of PWM dignity has been ripped away. He will forever giddily collect his extra amps wondering if those poor people using PWM knew what was just beyond their grasp."