This isn't a trick question. I wish to take a "Short Course" in the reality versus hype of MPPT control... Users who have MPPT and can report real-life experience...Let's say I get a pair of panels rated oh say, 180 watts each with a working voltage of how much (?) 36 volts... (360 watts of panels)Arizona, high noon. 90F. perfect panel angle.Battery bank at 12.25 volts static.Monster size wire connecting panels to controller to batteries. Call it .2 ohm total resistance point to point.What is a reasonable expectation for amperage delivered to the batteries?Under the above operating condition, are some MPPT controllers more efficient than others? Are some more efficient than others with LESS direct angle of sunlight?I am considering hauling panels back to Michoacan from where the hell is that place near Corona, CA.?Has anyone reconfigured an array to double voltage with the available panels and controller, then verified total WATTAGE delivered to the battery bank did not degrade?For long-term use does very high array to controller voltage, say in excess of 50 volts cause the silicon wafers to degrade faster?This is where I learn from others on this forum. Thank you in advance.

Wow! you lost me on this question. I've not no idea what you're talking about! It must be something about solar panels, satellite systems, a new flush system, or some kind of new tow vehicle!

One question you likely will get answers that are guesses is what MPPT controller is better than another. You will not find many that have actually purchased several to see which one is best. I bought ONE a Blue Sky Solar Boost 302? 40a controller and it works fine. Is it better or worse than others I have no idea. I have seen 42-43a at times and that is good enough for me.

My proven method for calculating "expected amps" when pointed at a high sun, blue sky, with PWM is: panel watts/130 x 8.2 = AIt has worked out right in real life using several different amounts, so it is fairly accurate, based on panels having an Isc proportional to a 130w with 8.2 IscSo 360w should get you 360/130 x 8.2 = 23 amps. (note some mono panels have lower Isc per watt so they come out less, but most poly seems to be in the ball park)Now what happens with MPPT? Most reports are that you get the same or a bit more, maybe 10% more tops. So your expected max amps with MPPT on 360w would be say 26 amps instead of 23.Note there are some claims that the MPPT does better in the shoulder hours so you get extra AH per day than just comparing the expected max amps. No figures on that if true even. Say you get 15% more daily haul but just the 10% more max amps? No idea.Note your controller whether MPPT or PWM should have an amps size 20% more than your expected max amps because there are times the solar does more amps than rated (edge of cloud effect is one) so for 26 amps expected, you should have a 30a controller. Some MPPT controllers clip the amps above their rating, so with them you can go to max, no 20% margin needed (eg Morningstar 15L ) With some PWMs they will let the amps through, but get too hot running above rated amps. The other thing with controllers is their rated max voltage intake--total Voc of panels. One more volt than that for one second and you fry your controller! Yipes! So you need to figure the total Voc of your array when it is as cold out (when Voc is highest--not the rated Voc at 25C) as you will ever be camping and then allow some more margin besides to be safe.In juggling panels and controller options you can have more than one controller, say if two smaller ones are cheaper than one big one. Same total amps on the battery.

Hi mex,The cable from the panels to the controller need to be large, too, for mppt to work well.In theory, 360 watts / battery voltage = input from the controller to the battery bank.Losses on a 36 volt system at the controller may run as high as 5%.The better the "smarts" in the controller the more energy will be harvested.I have seen 17 amps from 256 watts on a system voltage of 33 input to the controller. The controller is a Blue Sky 3024di (so one generation out of date)..I don't see 17 amps very often unless I run the inverter/

i have a blue sky 2000e MPPT controller, it is possibly one of the oldest MPPT controllers aroundset points can be adjusted by the POT's on the inside36v panels and above is where you will really see the advantage MPPT where the output amps will be higher than the panel rating and the controller can maintain the bulk voltage set pointmy low voltage panels don't allow for as much AMP gain above rating, as higher voltage panels, but the MPPT does mean the bulk voltage/peak voltage is maintained, even at low amps, so i get a better top off than PWMmy 2000e has a peak voltage rating that is NOT high enough to allow for series panels, if i ever change controllers, i will get either an 'Outback' orone of the new cheaper high voltage chineese controllers that have been posted in this forumIF you get a 90v controller you series the 36v panels =72vbut the 50v mark 'for series panels' is Not attainable unless you go with lower voltage panelsmy 505w of low voltage panels , Flat on my RV roofcollected 70.78 AHr , 957.5 watt hrs, Thursday, with a PEAK 14.47 AMPS / 195.1wattsthis in smoggy calif, NOT QZ Az

Usefulness Of MPPT Technology | Good Sam Community

56 Replies

MrWizard
Moderator
Jan 02, 2014
Hey Mex Glad to hear your on the road to recovery
westend
Explorer
Jan 02, 2014
Well, Mex, you were in that "Thank God they have something that works" situation. Hope you get healed up and headed home right quick.

FWIW, I have a kidney stone factory located inside me and have found that cranberry juice is a pretty fair elixir. Last time I was at the specialists, they located nine stones from the MRI but didn't think it was much of an issue. Bastardos!
NinerBikes
Explorer
Jan 02, 2014
Could have got panels in Corona, made in Germany... Maybe next time. If they are used, are they exempt from taxes and import duty??
pianotuna
Nomad III
Jan 02, 2014
Hi Mex,

I'm glad they found what would fix you.
MEXICOWANDERER
Explorer
Jan 02, 2014
A seven hundred seventeen dollar synthetic (amino acid based?) antibiotic IV injection? Well I couldn't have gotten THAT in Mexico. It seems to have worked miracles. And a grocery sacks of other meds. Went code 3 ambulance the last 300 miles to the border then transferred to an EMT ambulance. They did not like the high fever part. Some stupid E-Coli-409-b strain - really does a number on the kidneys. I wanna go home now.
JiminDenver
Explorer II
Dec 31, 2013
Good luck Mex.

Happy new year too.
westend
Explorer
Dec 31, 2013
Vaya con dios, Mex! Hope you're up and posting real soon.
NinerBikes
Explorer
Dec 31, 2013
MEXICOWANDERER wrote:
The absolute cheapest panel available costs $2.96 per watt plus 16.0% IVA sales tax. Then to ship Estafeta, $58.92 plus oversize fee of $22.00

Mexico is NOT cheap. Not anymore. But basic foodstuffs and basic services are a lot less expensive than the USA. Here while I'm waiting for my house to get outfitted a rental costs $1,000 pesos a month, around 82 dollars.

Anyway I am fleeing northbound in a few minutes by bus. My kidneys do not like me any more. Fever, pain, and my USA doctor told me to get to a hospital ASAP. I will probably end up at SCRIPPS hospital on H street in Chula Vista. I will leave word everyone can call, and all visitors except bill collectors and people who hate RV's are allowed to visit. I doubt I will have internet service for my laptop. Hope this isn't a Roach Hotel scenario :(

That looks more Mission Valley than Chula Vista on my Google map.
mena661
Explorer
Dec 30, 2013
pianotuna wrote:
Hi Mex,

Get well soon. In my prayers you are.
X2, get well old feller.
pianotuna
Nomad III
Dec 30, 2013
Hi Mex,

Get well soon. In my prayers you are.

Forum Discussion

Usefulness Of MPPT Technology

56 Replies

About Technical Issues

Related Content

New generator technology product

add another MPPT

mppt vs pwm

MPPT Controllers

Advanced Technology