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Just forget 12 volts all together. 12 volts is for cars and toys, If you are off grid 12 volts is no good way to go. If you have access to grid power use grid power to charge your batteries. and grid tie your panels. if you are truly living or wish to live off grid, you should only consider 24 volts or higher. most 12 volt ceiling fans I am aware of will also run from 24 volts. batteries are a losing investment, solar is a poor way to charge batteries to begin with and if you use inferior equipment and you will be replacing them sooner than later. If you already have a batteries and have been charging from solar panels, I would check the health of that batteries. and plug into a good charger right a way. an improper solar battery set up is good at destroying expensive batteries in short order.
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You need to learn what Comic Sans MS script is is and how to read partner. I gave you exactly what you needed to know why, and explained it in great detail You would be a fool to use PWM and any voltage less than 48 volts.
Again which is less expensive.
6000 watts of Panels for PWM
or
4000 watts for MPPT.
READ CAREFULLY, they both generate the same exact amount of power. Both require 48 volt battery and 80 amp controllers.Last edited by Sunking; 07-11-2016, 09:18 PM.MSEE, PEComment
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Considering my local location (6 hours sun hours per day and never more than 2 following days cloudy here until sun comes back and no more than 40 cloudy days a year), this is the answer from Morningstar Tech Support after calculations. Obviously they'd prefer to sell the most expensive device but apparently they try to be honest and above all GIVE ADAPTED ANSWERS AND ADVICES to their customers. I got the same answer from my local dealer that advised me to go with PWM with the solar panels I have available here. Maybe they both are fools but I will stick with Morningstar Tech Support advice (specially when they advise me a less expensive device when one would expect the contrary).
Saying MPPT is better is SO easy (even me a newby I can say that!) but that was not my initial query. PWM (for a reason I admit I do not know) allows me to install more of those panels (the ones only available here as I stated it in my first post) than MPPT and cost nearly 4x time less . Going with a 48V system duplicate the batteries I have to buy when only 4x435ah L16 in a 24V system is enough for my needs and in my location. I can draw 6000W (40% SOC) and get 2days back up until sun kick back for minimum a week (even in the rainy season) .
Going 48V as you "advise" will need 8x225ah T105 6v batteries, more maintenance and above all NOT NECESSARY! I need to stick with a 24V system and if my economy gets better in the future I can add more batteries and panels.
I am afraid you did not get the all picture of my queries and just tried to show off not considering all the variables that I stated in my earlier posts. And not speaking about your nasty sarcastic and pedant way. This is why I suppose there are good, honest and pertinent supplier/dealer... and the rest.
Morningstar Corp. Tech Supportvia 2isxwz4yimt5l6sd.tncf8291yjaqxqbd.3a6vrl.3-oneaeai.na13.bnc.salesforce.com
Hello Sir,
The MPPT may or may not help, it will be able to boost your input voltage. Really your issue is the voltages of those panels. You will likely harvest more power with a MPPT controller but if you do not have enough input voltage it still will not matter. The TS-MPPT has a max input voltage of 150V and at 45V each you will be under 150V but not by much(45V x 3 = 135V). Since you are in a warmer climate this will most likely be fine and keep you with enough voltage to equalize. I changed the string calculator to the TS-MPPT-60 and you can see that your max Voc, based on the temps you provided will be less than the 150V so you should be fine.Having MPPT is not necessary but it does provide some benefits where PWM cannot. I have attached a few documents below which may help guide you.
http://www.morningstarcorp.com/wp-co...ogy-Primer.pdf
In your situation(location, temperature, panels available, etc) I would say staying with PWM will likely be more than fine. If the system is sized appropriately and as you are able to reach absorption and float everyday than having MPPT is not necessary, you may just get into regulation a little sooner in the day.
With no more to say here (unless in a decent manner).
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Only if you do not consider the cost of the panels. The only way that PWM makes sense is if you:
1) already have the solar array and you have way more power than you need and
2) you will never expand your system.
Otherwise, buy 20% fewer panels and put that money towards an MPPT.
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Hello,
It is not that I do not consider the cost of the panels, as I posted earlier I can only get those 320W panels here or import others (4 months with all the import problems and high custom taxes if you are not a dealer). In my location (never more than 40 cloudy days a year and never more than 2 following cloudy days in a row) and with my actuals needs, I will only have to put 4 of those panels and 4x6V 435ah batteries (24V system).
Going for a 48V system (as sarcastically suggested earlier), 8 batteries, MPPT will cost me more money and more maintenance. MPPT controller here cost $850 compared to a 60A PWM that I can get for $170. If I want to expand (and if my economy allows it) I could then buy 4 more batteries. All together and to start with, MPPT solution in a 48V system cost me $1600 more than PWM. A lot for me at this moment of my life.
In the future, by just adding 4 batteries (435ah 6V) and keeping with my 4x 320W panels (effective 4700W with PWM @ 61% and 6 hours sun per day) I can get 20kw/h stored, use 3 or even 4kw a day (1kw/h more than my actuals needs) and still have a confy back up. Right now with my plan to start with 4 batts (6kw/h useable), i still can manage it by being careful on my loads during 2 months per year when consecutives full day cloudy days. If I get 3 of them (rare here and I still can get maybe 25% energy harvest from the panels), I can always use the generator for 2 hours during my heaviest loads.Comment
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I love this post, and I have an additional question. Is there a reason why all examples all online calculators we can find on the internet are restricted to 48Vdc?
My first reaction would be to have the highest voltage and the lowest current where I would consider 100-125A as a MAX value.
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Maybe for safety. See https://en.wikipedia.org/wiki/Extra-low_voltage
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That would be a mistake; you'd never be able to get a full charge, and your batteries would die prematurely. With a 20kwh battery system you will need at least 2kw (effective) worth of panels.In the future, by just adding 4 batteries (435ah 6V) and keeping with my 4x 320W panels (effective 4700W with PWM @ 61% and 6 hours sun per day) I can get 20kw/h stored, use 3 or even 4kw a day (1kw/h more than my actuals needs) and still have a confy back up.
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Ohhhhhh! That is a bad news indeed.
I made some calculations (for what it worst) and with 4 panels with PWM I can produced 4700w effective a day. Less my daily load (let's say 4000w maximum in the future) it leave me with only 700w a day to add to the batteries. You are right, during the wet season and after a bad cloudy days combination, it will take me like 10 days to be @SOC 100%.. I will have to add 2 panels to cover that deficit. Increasing only the battery bank is indeed not the solution and with my location sun pattern I'd have to add 2 panels with PWM controller to harvest the most when I can (during the 3 months wet season there are no more than 3 cloudy days per week) and keep the batteries bank as it is for the time being. In that case It may be better to use MPPT, still will have to get 1 more panel instead of 2 with PWM and not increase my battery bank.
One thing is sure, I can not go 48v (as repeatedly hammered to me) because I can not afford 8x 435ah batteries to start with + MPPT + 5 panels + set of 8 more batteries for extension unless I start with 8x225ah batteries (same price than 4x435ah). But then if I need to extend my battery bank I will have 16 batteries in total and that sound a lot to me.
Bottom line and after your comment, I think the best bet will be 24v, MPPT45A, 4x 435ah batts, 4 panels and extend in time @ 5 panels and maybe 4 more batts. I ran the online string calculator with the TS MPPT 45A (cheaper the 60A model ) and yes I can have 5 panels but no more. Last but not least, I now need to calculate the budget but at first glance it does not look that I can afford it or accept to run my 240v generator like 40 hours a year (better for my cash flow).
Thank you.Comment
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Sounds like you are still missing some of the fundamentals to system design. How much energy do you require?
If your plan is to go with a 24 V system with 4 X 435 Ah batteries, that is 10440 Wh (Plan to discharge no more than approx 3500 Wh daily).
In a 48 V system, that 10440 Wh would be achieved with 10440 / 48 = 218 Ah.CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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Energy required: 3200w/h with possible expansion to 4000w/h
batteries: 4x435ah @ 24V
CC: TS MPPT45A
Inverter: Magnum MS4024 Pure sine wave (for my laptop and some electronic I need to run)
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Ok, so how does the cost of 4x435 Ah (6 V in series for 24 V) compare to the cost of 8x225 Ah (6 V in series for 48 V)?CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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Why would I complicate my life if I can simplify it? 8 x 435ah batts is more than enough for me in the future. The last thing I need to see is how many more panels I will need to insure my 8 batts are properly charged and if the controller I chose will handle the increase in panels.
I have the other option, again in 24V, to buy 8x225ah to start with and then buy 4 more. 12 batts in total sound better than 16 and maybe I can stick with the TSMPPT45.Comment
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