Renogy vs Solar Blvd Panels

xyzHollyxyz

Yesterday, I bought a 2nd flex panel off Ebay with these exact Renogy specs for $187. Several hours later, this Solar Blvd panel for $119 was brought to my attention. Would the $119 panel have been compatible with my Renogy panel. How do the two panels compare - all those numbers are greek to me (I'm just trying to keep my fridge running on propane while boondocking). Thanks for you help. Also, I noted that the Solar Blvd panel has S-S connectors? Never heard of them. 

BB.

In general, for charging a 12 volt battery bank with a simple PWM (less expensive) charge controller, you are looking for panels with Vmp~18 volts +/- 1.8 volts to put in parallel (I would suggest Vmp~17.5 volts rated minimum) will be "optimum" for your needs.

"Flexible" panels (made from plastic cover+substrate) are something I would suggest you avoid unless you have special needs. More or less, the flex panels I have seen may have as short as 2-5 year life before they begin to decay. If you have need for flex panels (boat, kids throw rocks at your array, etc.)--Flex may meet a need.

Simple glass panels are very fragile (shipping, storage, installation, hail+rocks+blowing debris)--But tend to have much longer life in day to day sun+weather.

-Bill

Vic

You may want to look at this,  regarding a FIRE HAZARD RECALL:

http://www.cpsc.gov/en/Recalls/Recall-Alerts/2016/RNG-Recalls-Bendable-Solar-Panels/

Have not studied these PVs,  however.   FWIW,   Vic

BB.

Ouch... I will have to add "fire hazard" to my standard rant against flex panels (it is very difficult to make anything made from flexible "plastics" fire resistant).

-Bill

xyzHollyxyz

Thanks, Vic! Just got off the phone with Renogy. My panel is NOT in the recall! Whew. I did not relish the thought of packing that thing up. 

So, on the original question - is one of those panels at the top better for one reason or another? 
Thanks again! 

BB.

Run the panels in parallel is fine (Vmp's are "close enough" for our needs).

You really cannot run the two different panels in series (Imp not really close enough together for optimum use).

What is your power need, and your plan (in parallel, what charge controller, what voltage/AH battery bank, how many AH/WH per day, etc.)?

-Bill

xyzHollyxyz

The only thing I need the battery for is to run my Dometic 2-door fridge on propane. I have disconnected the seal heater (power-sucking monster) which, on my big trip last year, I did not know existed and made me not understand why my battery went dead so fast. 

I currently have this controller (pic below), but I recently saw a youtube video that criticized the heck out of it - said it's DEFINITELY NOT  an MPPT, and not really even a PWM (he had the thing opened up and had all sorts of meters attached to it and measuring stuff...)
This guy had so many complaints, he had to list them all in TWO videos! I have ordered a PWM controller from Ebay (el cheapo). I will only use a solar set-up maybe 20-25 days a year, during my annual "Big Adventure"...

First pic is my "setup", which I was using to show a friend just starting in this confusing solar world. (The sleeping bag is the travel storage container, and the Camp Pot Battery was because I was too lazy to go to the garage and get a real battery...) 

BB.

What size battery bank (and have you replaced the batteries since they last "went dead"--usually lead acid batteries do not recover).

And, have you measured you loads? Many people find that the forced air space heater typical in an RV can also drain batteries quickly. I am sort of surprised that your refrigerator ran the DC heater automatically(?). I would have thought that there would be a "DC Cooling On/Off" switch.

I would suggest a "cheap" DC Current Clamp DMM (like this one) and learn how to use it. There are also DC AH/WH meters that are very nice for smaller DC loads.

The DC current clamp meter is great for debugging and understanding how things work. the DC AH/WH meter is good for measuring total energy usage over a 24 hour (or whatever) period--Clamp meters do not really do a good job of estimating energy usage (i.e., the fridge is on 10 minutes for every hour, or on for 30 minutes every  hour--this example would be a 3x more energy usage because of the 30 minute vs 10 minute duty cycle).

Once you get a good handle on the "energy math"--It should help you understand and design a system that better meets your needs.

-Bill

xyzHollyxyz

A few weeks ago, I replaced my single original group 27 battery with a single AGM Group 31...hopefully, I'll never have to lift it off the tongue because I couldn't! I have "tongue weight" issues (I would have just said I have weight issues, but you would have thought I should just lay off the ice cream ...) so, I can only have one battery. 

A couple of weeks ago, I bought just the Clamp Meter you linked to (except I paid the full $60!). I don't know how to use it, but if it ever cools down, I'll go out to the trailer and give the meter a try. Which battery cable to I clamp around  + or -? 

I have a battery lantern, all trailer lights are LED, don't use the water pump, don't use the furnace, don't use the water heater. 

The only MUST DO is to wash my hair daily. My little Honda eu1000i is considered the world's most expensive hair dryer...

So, I am hoping that 2 x 100W panels will take care of my battery/fridge problem. If not, I gifted myself with a Yeti Cooler for Christmas! 

BB.

OK... I paid $60 too--And they now have closed the Sears that was three blocks from my home (it was getting pretty "sad" there in the last decade or two anyway).

With the Clamp Meter, I found it very easy to use on my car. Clamp across the + battery lead (or negative, does not matter--But you have to remember that it only measures the current through the wire--If you have two wires and clamp across two wires, then total current flow. If you clamp around 1 wire, only current in that wire. Note it is "net current"... If you clamp the + and - wires going someplace--The +4 amps will cancel out the -4 amp current flow and read "zero" amps total).

The meter also has a "zero button"... That takes a bit of practice. DC Meters "drift" and do not have "zero current" reading--you have to tell it to zero/calibrate itself. With no wire going through the clamp, you will push the "zero" button (and the LCD should say ZERO)--That that point, is is now calibrated to read 0.00 amps. Put the clamp on one wire, and you will read the DC current (there is a + / - on the screen, so you can figure out which direction the current is flowing--but that is is usually to confusing to worry about).

Zero the meter and clip it to your + lead on the battery (newer cars may have lots of + leads going to various places in the car--In that case, connecting to the single - lead is easier and works just fine).

You should see near zero amps. Turn on the headlights and you should see ~10 amps. Start the engine, and you should see the +- sign "flip" as the alternator begins charging and see ~10-50 amps charging, then slowly drop to 10 amps or a bit less.

And that is how the meter works. You can play around (with the engine off) and see how much current the radio draws, interior lights, etc.

A "typical" Group 31 battery may be around 100 AH (20 hour rate).

http://www.trojanbattery.com/pdf/datasheets/31AGM_Trojan_Data_Sheets.pdf

You want to figure out your loads... Are they 1 amp for 12 hours over night (that would be 1 amp * 10 hours = 10 Amp*Hours). And measure/estimate every load. Note that some loads may be 10 amps for 1 minute (1/60th of an hour) and may drop to 0.0 amps or 0.5 amps etc... It all matters (i.e., 10 amps * 1/60th hour + 0.6 amps * 59 minutes/60 minutes per hour = 0.76 AH over a 1 hour period).

A 100 AH battery should have ~5% to 13% rate of charge from solar---Or ~5 amps to 13 amps:

• 5 amps * 17.7 volts Vmp = 88.5 watt panel minimum
• 10 amps * 17.7 volts Vmp = 177 Watt of panels "nominal"
  
• 13 amps * 17.7 volts Vmp = 230 Watt "cost effective" maximum panel
  

Anyway--That is based on the battery. Of course, still need to know your loads to calculate solar panel sizing that way too.

-Bill

xyzHollyxyz

THANK YOU! I will have to print that out and study it!

Next question - I am playing with a Renogy PWM charge controller I found and never used. I took my 100W flex panel outside and went to hook up the MC4 extension cable to the leads off of the panel.

Well, I had my glasses on and noticed (for the first time), that the MALE (POSITIVE ) lead on the panel has a " + " on it, and the FEMALE extension cable has a " - " on it. The two pieces fit together in either orientation. Should I have the + and - on opposite sides when I plug them together, or does it not make any difference? 

BB.

Solar panels have been called "solar batteries" sometimes... And like batteries, if you want the current to add--you connect in parallel--Or + terminal from panel 1 to + terminal to panel 2, etc. and all of the + terminals from the panels to the + terminal on the Solar Array input to the charge controller. And--All of the - terminals are grouped to all the other - terminals the same way.

If you needed to do series connections (where you wanted 2x 18 volt Vmp panels to be 1x 36 volt string), you would connect the + terminal of one panel to the - terminal on the second panel. The free end of each panel now becomes the 36 volt output. But in your case, I do not think you need (or want) to do that.

In general, you should connect the + and - to the 12 volt battery first, then connect the final connection from the solar array to the charge controller... In some cases, connecting the solar array (under sun) to the controller first, then to the battery bank, will "confuse" the controller.

http://hespv.ca/blog/wire-solar-panels-parallel-vs-series/

Do not trust +/- markings on the MC4 connectors--Different vendors have been known to mark them up differently. Use your volt meter set to DC volts and measure to make sure that + and - Leads are connected together correctly.

Hooking panels / batteries / electronics "backwards" can "instantaneously" destroy your panel and/or electronics.

And, you should have an appropriately sized circuit breaker (or fuse) for every "red + wire" that leaves the battery bus (pop the fuse instead of catching your wiring on fire).

-Bill

xyzHollyxyz

I just read about the fuses yesterday...need to look into how to add it! Hopefully, there's a youtube video!! 

Here is a picture of the conditions under which I'm testing a different controller (the pond is directly west) - a PWM that I have never used. I hooked up the battery to the controller first and then the panel to the battery. ALL 3 lights immediately lit up red. Is that a good thing or a bad thing? The battery should be in a pretty charge condition. I do not have any instructions for the controller. 

Vic

Regarding the manual for the cmtp02 CC,  just try Searching for "  cmtp02 manual  "

Found this on Google,  BUT,  this Link will probably expire in a day or two.   The manual is very terse,  but probably adequate verses having no manual whatsoever:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0ahUKEwiO2pjV-q_NAhVB92MKHb_eAioQFggrMAI&url=http://vodasi.com/?m=common&a=down&name=554f7803f29b7.pdf&usg=AFQjCNGOmwjFZTq2yO5v1t7VOwC30UReMQ

More Later,   Vic

xyzHollyxyz

I read that manual, and also found a different one. I think that those 3 solid red lights indicate that the battery is in good shape. I put my multi-meter on it and it read 13.45ish. I put my clamp meter on the red wire from the panel and it was right around 1.0A, give or take a bit. 

xyzHollyxyz

Is this the type of fuse holder and fuse (blade, 30A) I should get? And since I have 10AWG wire, I should get a 10 gauge holder? I cut the red wire and put it in line on the positive side of each of the 2 100W panels? Is polarity important with the fuse holder/fuse? 

BB.

For your small(er) system/array--you do not need any fuses in the solar panel side.

You only need fuses (and matched wiring) on the battery + side.

Here are two basic charts for wire size vs current... The NEC one is very conservative (and has even further deratings for conduit fill/temperature/wire insulation type/etc.). The Boating one is much less conservative.

https://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm
http://www.boatus.com/boattech/articles/choosing-cables-and-terminals.asp

What ever is the maximum continuous current that you expect to run, multiply by 1.25x (solar charger side, you may want to multiply by 1.56x).

Say 13 amps of solar...:

• 13 amps * 1.56 derating = 20.28 amps ~ 20 amps minimum fuse+wiring
  
• Marine table ~16 AWG minimum
• NEC table ~ 12 AWG minimum

With solar, you generally want to go with heavier gauge wiring (more efficient, keep voltage drop "low" on 12 volt systems, etc.). 12 AWG or 10 AWG is very good (conservative) for 13 amp solar charging system.

I am not a fan of the automotive blade fuse holder (they can overheat). If you use them, make sure that the fuse holder is not in a flammable space (laying on wood/combustible materials).

-Bill

xyzHollyxyz

200W / 12V = 16.67A ?
I recently remade my extension cables with 10 gauge wire. I'm good to go, right? 

And my previous question about polarity of the fuse is dumb because it'll only be on ONE wire...
Should the fuse be 30A ? 

BB.

Well, the math does depend on your exact configuration... For a PWM type charge controller, you look at the Imp Rating on the panels (which panels, you have two different Imp ratings, one each, 2x one of them, etc.)... Or a rough (conservative):

• 200 Watts / 17.5 volts Vmp = 11.4 Amps Imp (from two panels in parallel, through the PWM charge controller to battery bank)
• 11.4 amps * 1.25 NEC derating for wiring+fuses = 14.3 Amps Standard NEC derating for all circuits (10 amp fuse running 10 amps can cause the fuse to blow in minutes/hours/eventually/or not).
  
• 14.3 amps * 1.25 NEC derating for Solar = 17.9 Amps (this may be a "bit excessive" of derating by NEC--Not sure that is really needed)

So, the minimum fuse/breaker/wiring -- A minimum of 15 amps--And you can go to 20 amps just fine. If you go with a larger fuse/breaker, make sure you have large enough AWG wiring to carry the current (fuses protect wiring--You want the fuse to be 30 amps, you want the wiring heavy enough to blow the fuse before overheating the wiring).

-Bill

xyzHollyxyz

I actually just ordered a 2nd flexible panel with EXACTLY the same specs as my Renogy above. I did not get the Solar Blvd panel. 

I just now checked the cable that goes from the battery to the controller - it is only 12 AWG. 
Do I use a 30A fuse? Or should I remake that cable, too, with 10 AWG, to be safe? 

BB.

12 AWG is more that heavy enough for 20 amp rated fuse (NEC being the more conservative).

Another check is the distance the wiring runs... Say it is a 10 foot run at 11.4 amps on a Vmp~17.5 volt array over 12 AWG:

http://www.calculator.net/voltage-drop-calculator.html

http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=5.211&voltage=17.5&phase=dc&noofconductor=1&distance=10&distanceunit=feet&amperes=11.4&x=44&y=10

Voltage drop: 0.36
Voltage drop percentage: 2.06%
Voltage at the end: 17.14

Typically, we aim for 1% to 3% drop voltage drop on wire runs (3% makes for higher losses and possible "low voltage" at load--1% is typically about as much copper / money a person would want to "throw" at the system).

The other question--Do you think you would ever want to add a 3rd panel (can you fit a 3rd panel)? If so, perhaps you would want to run a 10 AWG wire from array to battery bank to allow for "easier" future expansion).

-Bill

xyzHollyxyz

LOL - no, I think my brain has all it can handle with TWO panels. And I'm not even sure about that.

Question - on your link to the calculator, where the variables are named below and within the formula, where did you get the wire size of 5.211? 

You sure have some patience, and patient people around here! 

BB.

That is 12 awg in metric (I think).

-Bill

xyzHollyxyz

BB. said:

That is 12 awg in metric (I think).

-Bill

OMGosh - I am having plenty of difficulty learning the English version of all this stuff, and now they throw metric at me! LOLOL. 

BB.

That was posted from my phone--I use handy dandy charts when conversions are involved:

http://www.technick.net/public/code/cp_dpage.php?aiocp_dp=guide_awg_to_metric

And 5.211]1 is not a metric cross with 12 AWG (at least not a straight metric cross).

Using this chart, I don not see any 5.211 conversion that makes sense either:

http://www.allenelectric.com/referencedata/wire_size_cross_reference_chart.htm

Duh... All I had to do was scroll further down on the calculator page, and there is it:

12 AWG -> 5.211 Ohms per km (kilo meter)... So the software guy just has a chart of wire resistance per AWG--And uses that for the calculation (and some metric/English unit conversions).

-Bill

papab

i noticed for that solar blvd panel that Isc was less than Im.   Does this make sense? 

xyzHollyxyz

papab said:

i noticed for that solar blvd panel that Isc was less than Im.   Does this make sense? 

HAHA - not to ME, it doesn't!
Not much of this makes sense to me.
Oh, wait - you did not pose that question to me, I'm sure. 
But I will await your replies because it's all a way to learn...

BB.

Something is wrong with the Isc and/or Imp numbers.

Also Voc and Vmp probably are a bit dodgy too.

-Bill

xyzHollyxyz

So, maybe the Solar Blvd panel is not such a great deal @ $119?

BB.

Don't know--But without knowing the correct numbers, you have to start wondering if they are XYZ Watts or not, and what else may be incorrect.

-Bill