Seeking your MPPT CC Advice - Off Grid

[SunEagle]

I never went with the cheap grid tied panels from craigslist. After all the differing advice and opinions I settled for a 100watt single panel kit from eBay. K.I.S.S.

Windy nation 100watt 12 volt panel 40 x 26
17.4 vpm
5.75 imp
10 amp pwm cc
20 feet of cabling
Mc4 connectors
Panel mounting brackets

From eBay for $169.99 shipped

This kit charges a 122 amp hour everstart group 29 marine battery which we use for camping.

Our main draw is a periodic 2 Ah from an ARB portable fridge freezer over an entire day. In the evening we will use a pair of 5v USB lights, under 2 Ah.

This is all we need for camping and emergency hone use with out spending $200-$300+ on an mppt.

Solar Peasant (aka TriggerGolf)

I understand you desire to keep the costs down and actually you can go to 200 watts of panels and still use a PWM charge controller but it will have to be a 15amp type..

Based on that 122Ah battery a single 100 watt panel at Imp = 5.75 will not be enough to charge it. You need to add a second 100 watt panel in parallel to the other. That will get you around 10 to 11Amps which comes to about a C/12 charge rate which is low but acceptable.

[TriggerGolf]

I bow to my superior...

I never went with the cheap grid tied panels from craigslist. After all the differing advice and opinions I settled for a 100watt single panel kit from eBay. K.I.S.S.

Windy nation 100watt 12 volt panel 40 x 26
17.4 vpm
5.75 imp
10 amp pwm cc
20 feet of cabling
Mc4 connectors
Panel mounting brackets

From eBay for $169.99 shipped

This kit charges a 122 amp hour everstart group 29 marine battery which we use for camping.

Our main draw is a periodic 2 Ah from an ARB portable fridge freezer over an entire day. In the evening we will use a pair of 5v USB lights, under 2 Ah.

This is all we need for camping and emergency hone use with out spending $200-$300+ on an mppt.

Solar Peasant (aka TriggerGolf)

[SunEagle]

My bride has already claimed Queen Of The Universe, so that position is taken.

As long as that doesn't make you the court Jester.

[Amy@altE]

My bride has already claimed Queen Of The Universe, so that position is taken.

I bow to my superior...

[J.P.M.]

Living Large, you'll make me blush. I used to be the "Solar Thermal Queen", SHW was my specialty, but when I got promoted last year I became queen of everything (isn't that a song?)

My bride has already claimed Queen Of The Universe, so that position is taken.

[Amy@altE]

Living Large, you'll make me blush. I used to be the "Solar Thermal Queen", SHW was my specialty, but when I got promoted last year I became queen of everything (isn't that a song?)

[Living Large]

Mike - how dare you mention a connector that the KING would disapprove. King - would a CC with USB 3.0 be OK? Or is your highness a blue tooth only guy?


Queen - do you think I should avoid the panels because they are old?


This was good feedback & advice.


Very cool.


King - do you guys have a FAQ? I received a couple different answers in this post. Perhaps you guys should group together and create a matrix of different panels, panel counts, CC & battery capacities. Can the solar royalty come together to help?


-SolarPeasant

I wouldn't put any stock in titles, but Amy and Dereck are very knowledgeable and have given me outstanding advice on this board, as many others have as well. I just hang in there and keep posting until I find out what I need to know, and try not to let myself have any knee-jerk reactions. It's the internet, you know.

I find the moniker "Solar Queen" rather endearing. Watch the AltE videos - you'll think you died and went to heaven.

[Bucho]

No. It's still a lead acid battery. If he was using am AGM battery it could possibly take that high of charge rate.
WWW

In that case would you explain Sunking's comment here:

* Hybrid Batteries are useful in RE applications. Like the name implies they are a cross between SLI and True Deep Cycle batteries. They have fewer thicker plates than SLI batteries to obtain some deep cycle capability, and lower internal resistance for decent high current charge/discharge rates. However the plate s are not as thick and heavy as True Deep Cycle batteries. So what you get is trade-offs.

They can deliver/take higher discharge/charge currents than True Deep Cycle, but not as much as SLI batteries. On the other hand they do not have the high number of cycles as True Deep Cycle batteries. For the FLA types you still have the lower limit charge rates of C/12 to prevent stratification, but on the charge/discharge side of FLA hybrids you can go as high as C/4, and some cases C/2.

AGM hybrids are extremely expensive and resemble SLI batteries more than True Deep Cycle. They are used in UPS systems, Golf Carts, Floor machines, and Electric vehicles where moderate amounts of high current is required with som efair cycle life. Hybrid AGM's have very low resistance and can take a C/1 or higher charge\discharge rates. The downfall of them they only have 300 to 500 cycles in them. Hybrids are best used in systems that are infrequently used with high discharge rates like Emergency power and UPS systems.

[Wy_White_Wolf]

Well he's using a marine battery not a deep cycle, so his battery might be able to take that charging rate, no?

No. It's still a lead acid battery. If he was using am AGM battery it could possibly take that high of charge rate.

WWW

[Bucho]

40A into a 120Ah lead acid battery is too high of a charge rate and will destroy it. That is a rate of C/3 (120/40). You need to try and keep that rate between C/8 and C/12 (15A to 10A) with C/10 usually being about ideal.
WWW

Well he's using a marine battery not a deep cycle, so his battery might be able to take that charging rate, no?

[Amy@altE]

Yah, BP made some quality products. If it is worth the risk knowing you will not have a warranty, $.50 a watt for BP is a killer deal. Again, watch out for shipping costs if they aren't local, that can mess up the whole deal.

[LucMan]

Wow, you got me on that one, I had never heard of a 50 cell module. I used to sell 54 cell modules, but never 50. I did confirm the specs, it is right. BP made very nice panels, but those are probably very old.

Anything bigger than a 36 cell module with a PWM charge controller is throwing power (and money) away. So you'll still need an MPPT with them. I'd still go with the Kid, but you could probably use 1 for the 2 panels, double check with their sizing tool, http://www.midnitesolar.com/sizingTool_kid/index.php.

The SX 3200 panels are 6-7 years old, I have 26 installed on my house. BP is out of the solar business, so no warranty.
For $100 I would snap them up in case I ever have one fail.

[Sunking]

Mike - how dare you mention a connector that the KING would disapprove. King - would a CC with USB 3.0 be OK? Or is your highness a blue tooth only guy?

I am just poking fun at Mike. He knows me well enough to know that.

[TriggerGolf]

RS-232? Ancient technology....

Mike - how dare you mention a connector that the KING would disapprove. King - would a CC with USB 3.0 be OK? Or is your highness a blue tooth only guy?

Wow, you got me on that one, I had never heard of a 50 cell module. I used to sell 54 cell modules, but never 50. I did confirm the specs, it is right. BP made very nice panels, but those are probably very old.

http://www.midnitesolar.com/sizingTool_kid/index.php.

Queen - do you think I should avoid the panels because they are old?

Both the Morningstar MSView sw and the Midnight Local App allow you to limit the battery amps via software in the MPPT controller

I know the Morningstar MPPT 60 has a web HTTP server built in, and is very easy to monitor and skip the optional $100 meter.

I dont know if the Midnight Kid is controllable via Local App or if it allows battery amp limit.

This was good feedback & advice.

Below you can see the box I made it also has a 99 volt LED meter to display the solar panel voltage. The mppt controller is to the right with very small LCD screen. My recommendation is get a LED display.

Very cool.

Charge current is determined and controlled by panel wattage. There is a couple of controllers out there that will allow you to limit current to some point but completely defeats the purpose. If you want to limit the current you select the right panel wattage, and that is real easy to determine Charge Current x Nominal Battery voltage Panel Wattage. So 10 amps x 12 volts = 120 watts. 5th grade math.


But that has nothing to do with what you want to do. At this point you have no clue what is needed because you failed to take the first most important step. You did not determine your daily Watt Hour requirement Until you do that you are just wishing and throwing money away. Once you know what the requirement is, then you design a system to meet the requirements. Fail to do that and 1 of 3 things happen.

King - do you guys have a FAQ? I received a couple different answers in this post. Perhaps you guys should group together and create a matrix of different panels, panel counts, CC & battery capacities. Can the solar royalty come together to help?


-SolarPeasant

[Sunking]

The Morningstar needs a RS232

RS-232? Ancient technology....