Solar Power 101 - "For Dummies"

Michigan_Mike

Pardon the above title as that is more of a play on humor, yet I feel a discussion like this could be a catch all if you will, would be helpful and allow others and people like myself a means of asking those of you who are tech savvy, seasoned/astute solar users questions and getting valuable information and insight gleaned on a great subject that is beneficial to everyone.  

So with that said I will start this thread out by asking the following as inasmuch as I have looked into this I wanted to pose the question to the forum solar gurus and firm up things I've found out, but am not certain are accurate.  

I recently purchased 2 - 235 watt (470 W of solar combined) monocrystalline panels and would like to use both in providing power to a remote outpost we will use in SW Arizona.   I'm wondering about the following and would appreciate some advice here:

1.  What size and type of solar controller would I need to run the two panels above?   

2.  Is there a preference in the type of cables I use in a hot environment?  

3.  Should I dismantle and store the panels out of the sunlight when I break camp and head home for 9 months to Michigan?  

4.  What should I do with the batteries during the time I'm away?  I understand that heat is detrimental to batteries as is cold so is there a "best practice" for storing batteries in high temperatures when they are not being used and the location is without shore power for a tender, etc.?  

5.  Are there benefits or power advantages of lets say a wet cell battery over an AGM type battery?  I'm fully aware that wet cells do let off gas and am wondering if there is a payback in energy having one over the other and whether or not it would be better to have the AGM units stored inside as opposed to away from the living quarters because of the risk of gas and an explosion?   Are the AGM's comparable to the golf cart size 6 volt wet cell style batteries?  Obviously keeping cost down is desirable, but what would you recommend?  

ScottG

Great thread! I'm no solar guru, but I'm learning. Here's my understanding (at least with regard to RV systems)...

Controllers are sized based on the amperage coming from the panels. The amperage depends on the wattage and voltage rating of the panels, and total voltage depends on whether the panels are wired in series or parallel. Series wiring has an additive effect on voltage but holds current constant. Parallel wiring holds voltage constant, but has an additive effect on current.

Watts = Volts x Amps. Assuming your panels put out ~18V max  and are wired in parallel, your amperage would be 470W / 18V = 26.1A. Therefore, you would probably go with a 30W controller.

PWM controllers are cheaper, but when they step the panel voltage down to charging voltage any excess goes to waste. MPPT controllers can convert excess voltage into increased amperage, thus boosting charging capability. Of course, this is only an advantage under optimal conditions when your panels are generating their full voltage.

jkjenn

Mike, this is a nice diagram that shows the series vs. parallel. With that much solar, you probably want to invest in a more sophisticated MPPT controller that can receive 24v and output to 12v maximizes what you are able to pull in. What you need to make sure of if you run in series is that your voltage from solar does not exceed the maximum input voltage or watts of your controller. 

SteveK

1. You need to read the spec sheet for the panels you bought.  Many 235W are made up of 2 120W panels in series and so have a higher voltage output than you would expect from a standard 12V panel.  Your choice of controller should be dictated by the maximum full output voltage and short circuit current available from your specific panels.  If you choose to wire your 2 panels in series, be sure that you double the voltage rating.  If you wire in parallel, double the current rating.
A simple PWM controller (AKA buck) can step the voltage down to your battery but can not raise the voltage if the panel is running in sub optimal sunlight conditions.  Under this condition, the panel current has to be reduced until the voltage is high enough to be used.  An MPPT controller (AKA buck/boost) can reduce or raise the voltage from the panels as required for maximizing charge current during cloudy, off angle, or partially shaded situations.  This means that the panel can be used at the maximum power point rather that the point at which the voltage is high enough.  If you get good direct sunlight and your panels are properly angled, PWM and MPPT will give the same charge current.  Under poor sunlight conditions the MPPT will give you 15 or 20% more charge current from the data I have seen.
Wiring in series allows you to use a smaller wire gauge from the panels to the controller.  The disadvantage is that the output current is limited by the lowest output panel so a shadow across one panel will reduce the total current whereas if wired in parallel, a shadow on one panel will only reduce the current from the panel being shaded.  You go down 3 wire gauges to double the current capacity so if a 10 AWG would do for panels in series, 7 AWG (6 AWG commercially available) would be required for panels in parallel (for instance).

2. PVC or vinyl (cheapest) insulation is typically rated for 60C (140F) or a little higher. This has to accommodate ambient temperature as well as self heating from charging current.  Wires rated for 85C or higher are commonly available and the insulation will generally be somewhat more resistant to UV (sunlight) and abrasion.  If the wire does not have a temperature rating on it, you don't want to use that wire.  UL requires the temperature rating, so no rating means the wire is not suitable for anything that could go up in smoke.  UL also evaluates the quality and stability of the insulation so I would look for UL rated wire to insure that you get years of service rather than chasing flaky wiring.  As you will be in Arizona, I would pay special attention to making sure the insulation is UV stable or is covered in a conduit or sleeved.  A year of sunlight in AZ destroys plastics.

3.  The panels are made to last 20 or 30 years on a roof so should be OK left out.  That said, there is theft, vandalism, hail, wind damage, and accumulated bird poop to think about.  You will have to be the judge of those risks.

4.  Heat, cold, and UV are all bad for batteries.  Wet cell more so on with heat as water evaporates.  AGM are sealed against evaporation but can loose water under extreme heat such at over charging or discharging.   Air conditioned storage would be optimal, but impractical.  I would suggest dry, relatively clean, shaded, ventilated storage.  Lead acid batteries (wet cell or AGM) should be fully charged before storage (hot or cold), and benefit from a battery maintainer during long storage.  Over 9 months, you will see significant self discharge to voltage levels that may reduce total life.  If you leave your panels up and connected to the batteries, the battery charge would be maintained.  If you choose to take down or cover your panels, then maybe a small, cheap 10W maintainer panel could be plugged in and that would keep the batteries topped up.

5. AFAK power density and conversion efficiency for wet or flooded cell and AGM deep cycle batteries are about the same.  The basic internal chemistry is the same, just the method of keeping electrolyte in contact with the plates differs.  Both styles are available as 6V or 12V cells.  AGM (sealed lead acid) cost a lot more, but don't need to be maintained.  If you opt for wet cell then you will want to be able to easily check water levels (esp in AZ) and use an inexpensive hydrometer available at any car parts store to check acid levels and cell condition.  Water loss is driven by temperature and time.  I think 9 months of summer in AZ should be OK if the batteries are in a shaded and ventilated storage, but you would want to check that they were topped off and the chemistry was good before you put them away, and again before you hook them up and start charging/discharging.  Flooded cell batteries are more prone to problems if they get tipped over or sloshed badly.  They also release hydrogen during charging (could be flammable but not a health hazard per se).  The flooded cells need to be mounted where you can service them while AGM can be mounted in less accessible locations.  With good care, flooded cell batteries can last just as long as AGM.  If you can't or don't keep them maintained, AGM will last much longer.

Hope this helps.  This is free advice and worth exactly that much.  Thank you for your work on this and the Little Guy board.

gypsy222

All I have done is use my 80 watt Zamp, and stock 12 volt battery......... Bottom line, I'm not qualified to provide feedback on this subject, however I would recommend watching some videos on youtube that are posted by, Deep Cycle Battery Supply San Diego.

https://www.youtube.com/channel/UCNNyY4e2p3Au088NkzE-Edg

Jeff seems to be a wealth of information on batteries and does cover some of the questions you are asking, specifically on item #5. Hopefully you find helpful.

T@Balong

This is already way beyond Solar 101!

Ratkity

@SteveK thank you for such a well-written post!

I've gone beyond the basics with studying solar myself and knowing 12V systems from growing up with rebuilding automotive systems, but I see there is much more to be learned about why solar panels behave the way they do. I apparently just know the basics of PWM and MPPT controllers and liked your explanation. You mentioned a feature I didn't know existed between the controllers. My basic information was if you are going to use less than "xxx" watt panels for X application, then PWM is sufficient. 

I used a 15W solar maintainer for the group 24 battery on my smaller teardrop (prior to T@B) and it seemed to work great - the battery just needed a periodic overnight charge, but the 15W maintainer stopped working for whatever reason after a couple of years. I was fortuitous enough to get ahold of an 85W rigid panel (and also was able to reach it to keep it clean - omg.. the pollen). I bought a highly-rated, but small PWM controller, but that panel was rarely shadowed where my teardrop was parked and the teardrop had little to no phantom power draws. Serendipitous. That no-name battery lasted 5 years and was still going strong when I sold the trailer - never needing any periodic overnight charging after installing that 85W panel. I knew how long I could camp on a group 24 and the 85W panel just allowed me to run the fantastic fan and 12V charger ports before I was at 50%.  Looking at the insulation rating of the wire as well as focusing on gauge was something I didn't consider in my first installation - just happened to have enough attached wire from the panel to reach the controller which fit inside the battery case (no monitor, just hand held meter).  

By happenstance, when I went to a 100W panel for the new T@B, I bought short cables that have the correct ratings for solar insulation (it was just easier to buy the cables already made by the company than buy wire, the MC4 ends and make my own... laziness).  It was a "permanent" installation. The panel was recalled and I swapped it out for a 2x 50W rigid suitcase model and a 40W maintainer panel. I also bought the correct extension cables with solar-rated insulation, again, fortuitous. Except.. I ran into a problem. The 40W maintainer panel couldn't put out enough power to maintain the battery with the T@B's phantom power draws. Mostly because the panel was in a fixed location and got shaded for part of the day. I ended up just plugging in the T@B because I already had a cord run outside for the motorcycle battery maintainer. I never ended up solving where to put the 40W maintainer and if it actually could keep up with the phantom T@B draws.

Where am I going with this (I ask myself as well)? I've been pondering how can I best use my 100W suitcase (and precious extension cables) while doing a little weekend boondocking extending my 110 amp hour group 27 battery - now realizing my power consumption and needs have changed because of different equipment (but very similar phantom power draws). It seems the mppt controller might be the way to go, seeing how the weather was in this past shakedown trip (half rain showers in the day - half sunlight). Now I know how much the T@B Alde is an energy miser while being tiny!! The 10 gal hot water heater in the new trailer is pretty misery and doesn't have to continuously run (well-insulated). The furnace fan seems to be an energy hog (it was a cold weekend). The panels might be better utilized with the mppt controller to squeeze that little extra power out of the panels. By the end of the weekend, my battery was at 12.1V. Of course, showing people the power awning, having them turning lights on and off and running the furnace constantly didn't help. BTW, the frig was pretty good at keeping temp.

So, thank you for the information! I think I'm getting the hang of this solar thing. 

ScottG

T@Balong said:

This is already way beyond Solar 101!

Agreed, but re-read the introduction to Michigan Mike's post carefully. Keep it comin'!

Ratkity

T@Balong said:

This is already way beyond Solar 101!

Oh, just keep t@bbing along and you'll get the h@ng of it @ll! (resistance.was.futile.)

SteveK

I just happened to think that I should have qualified my post that some of the information was specific to Mike's situation where he appears to have a permanent or semi-permanent solar setup.  If you are using portable solar cells and batteries on the trailer, then some of the advice, like wire type, is a bit more than is really needed.

Ratkity

Steve, it was still great information! Things to store in the brain to consider if my setup changes. It was all very interesting.

Michigan_Mike

Awesome information!  I'm in the road right now and we are headed fir AZ.  The panels are locked down in the enclosed trailer so when I get to AZ I will look closer at the panels and photograph the ID plate and post it here.

irvingj

Great info, and this is the kind of info that's applicable across the board; thanks! (Even though we don't have our T@B now, we do have solar on our RV so this is good stuff!)

larrygon

Michigan_Mike said:

I'm in the road right now and we are headed fir AZ. 

If you are passing through Flagstaff AZ, look me up!

dundons

My 2 cents:
 I just upgraded from an 80 w portable Zamp panel to a 160 w since we camp in Yosemite for 4 weeks as Summer volunteers and most campsites are in partial shade. Last year I was unable to keep our 2 GC batteries charged by solar. My dealer was kind enough to take back the smaller unit toward the more expensive one. I also added a 15 ft extension cable giving me 30 ft to play with as I chase the sun around the campsite!

GrandmasKid

dundons said:

My 2 cents:
 I just upgraded from an 80 w portable Zamp panel to a 160 w since we camp in Yosemite for 4 weeks as Summer volunteers and most campsites are in partial shade. Last year I was unable to keep our 2 GC batteries charged by solar. My dealer was kind enough to take back the smaller unit toward the more expensive one. I also added a 15 ft extension cable giving me 30 ft to play with as I chase the sun around the campsite!

I'm curious about how many  amp hours you have in your two GC batteries. We have the 160w Zamp and a 90 Ah battery, and I'm hoping that will be enough capacity for dry camping in high high country in Colorado this summer.

jkjenn

GrandmasKid said:

dundons said:

My 2 cents:
 I just upgraded from an 80 w portable Zamp panel to a 160 w since we camp in Yosemite for 4 weeks as Summer volunteers and most campsites are in partial shade. Last year I was unable to keep our 2 GC batteries charged by solar. My dealer was kind enough to take back the smaller unit toward the more expensive one. I also added a 15 ft extension cable giving me 30 ft to play with as I chase the sun around the campsite!

I'm curious about how many  amp hours you have in your two GC batteries. We have the 160w Zamp and a 90 Ah battery, and I'm hoping that will be enough capacity for dry camping in high high country in Colorado this summer.

That will depend on your usage. I camped in the high country, last summer. I am a high power user but got by fine with 2 GC batteries (225 ah) and 200w of solar.

ontheroad

just bookmarked as I believe hubby and I will use solar at some point...even if we do end up getting "his" generator

dundons

@GrandmasKid, High country = shade=no solar. But, I have learned to shut off the 12v fridge at night and not to do a lot of phone charging at night and got a heavy duty Zamp extension cable to let me chase the sun better. You may want to add a second battery next year after you see how it goes.

dundons

@jkjenn

Next question:  Can I use the Zamp Solar plug on my T@B trailer to attach a Deltran Battery Tender Jr.?

I know the polarity is reversed on Zamp’s cable connectors but what’s to keep me from using a Zamp extension cable from the battery charger to the Zamp plug? 

luvmytab

That will depend on your usage. I camped in the high country, last summer. I am a high power user but got by fine with 2 GC batteries (225 ah) and 200w of solar. 

Jenn Grover

I live in Colorado and camp a lot here. I have heard a lot about GC batteries and want to get them but they do not fit into existing battery holder on T@B. Unfortunately, have not developed handyperson skills thru my life. Anyone out there who can give me a step by step on this procedure? or direct me to one already on this site? Must be very remedial, however!!!! I am about to purchase a regular interstate battery that fits just to be done with it but I love the idea of GC batteries and a little solar. The mountains are  beginning to call me and I want to be ready. We just had a bunch of snow up there so may be a while.  I'll head to Arizona and Utah and New Mexico until it melts. Thanks!!!

Ratkity

dundons said:

@jkjenn

Next question:  Can I use the Zamp Solar plug on my T@B trailer to attach a Deltran Battery Tender Jr.?

I know the polarity is reversed on Zamp’s cable connectors but what’s to keep me from using a Zamp extension cable from the battery charger to the Zamp plug? 

No. You need an SAE adaptor to change the positive and negative terminals from the proprietary Zamp plug. I don't believe it's expensive.

ScottG

Ratkity said:

dundons said:

@jkjenn

Next question:  Can I use the Zamp Solar plug on my T@B trailer to attach a Deltran Battery Tender Jr.?

I know the polarity is reversed on Zamp’s cable connectors but what’s to keep me from using a Zamp extension cable from the battery charger to the Zamp plug? 

No. You need an SAE adaptor to change the positive and negative terminals from the proprietary Zamp plug. I don't believe it's expensive.

Agreed. If you can crimp or solder wires, you could even make an adapter, or just flip the connector on your battery tender.

Whatever you do, just pay careful attention to connecting positive to positive and negative to negative and all should work fine. Trace all wires visually or ring them out with a multimeter. Unless you are willing to risk damaging something, do not simply assume that a particular adapter is correct just because the package (or somebody here) said so. There are too many possible configurations to give a single definitive answer without checking for yourself!

Sharon_is_SAM

dundons:

OptiMATE CABLE O-27, Adapter, polarity, SAE

Easy and cheap.  Just plug into your Zamp Solar outlet and then plug in your battery tender into the other end.  We had the same issue.

Marceline

I recently bought a 2013 T@B CS-S that came with a "Instapark Mars-100" suitcase type solar panel.
I am a complete newbie to solar (not to mention RV electrical systems) but I did manage to hook the thing up using the cable with alligator clip ends directly to the battery. I got a bunch of green lights and it seemed to keep the T@B battery charged while I ran the stereo and fan. 
It seems like this panel uses something called an "Anderson PowerPole" connector, which is different from the connector wired into the T@B battery compartment. Is there some kind of adapter that I can use? I haven't been able find it. It seems like it should be something like the adapter shown early in this video. 
But I haven't been able to find it. Any ideas?

pthomas745

Actually, the cable the guy in the video is holding looks like just what you would need.  (You do not need the "Roof" connector he shows you in the video...you should have one attached to your T@b.)
.
The adapters do exist.  I searched for "Anderson to SAE adapter"  and found one like this, and there are several more.

http://invertersrus.com/product/go-power-sae-solar-plug-gp-psk-sp/

You will just have to insure the SAE cable that plugs into the Zamp connector on the T@b has the proper "polarity."

And, since it is the middle of the night, I'll let someone else pick up the polarity answer!  (it isn't hard!)

Sharon_is_SAM

Marceline, to continue from ptthomas, the connection for solar on our TaBs are the Zamp brand.  Unlike convention, where the positive part of the outlet plug would be male, Zamp wires the port on the TaB opposite.  So, in addition to the Anderson to SAE adapter noted by ptthomas, you also need to use another adapter.

Copy and paste the link below.  I can't seem to make a direct link today.
www.amazon.com/OptiMATE-CABLE-O-27-Adapter-polarity/dp/B00AHCWGOO/ref=sr_1_1?ie=UTF8&qid=1495535795&sr=8-1&keywords=OptiMATE+CABLE+O-27%2C+Adapter%2C+polarity%2C+SAE

Sharon_is_SAM

Marceline, BTW, you can also use this adapter to plug in a battery tender into the Zamp port to charge your battery.  Again, unless the battery charger is wired like the Zamp, you need the adapter.

jkjenn

luvmytab said:

I live in Colorado and camp a lot here. I have heard a lot about GC batteries and want to get them but they do not fit into existing battery holder on T@B. Unfortunately, have not developed handyperson skills thru my life. Anyone out there who can give me a step by step on this procedure? or direct me to one already on this site? Must be very remedial, however!!!! I am about to purchase a regular interstate battery that fits just to be done with it but I love the idea of GC batteries and a little solar. The mountains are  beginning to call me and I want to be ready. We just had a bunch of snow up there so may be a while.  I'll head to Arizona and Utah and New Mexico until it melts. Thanks!!!

My first GC battery set-up used a battery box in front of the LP cover.

ScottG

This thread recently recaptured my attention. As is often the case, we've strayed a bit afield of @Michigan_Mike's original post.

Mike, before posing your questions, you indicated you already some impressions. Please share what you found, and if it's consistent with what others have contributed since then!

Marceline

Hi all, thanks for your help.
I just found this adapter.
Would this work? 
If so, am I correct in understanding that the arrangement on the left side of the image (positive line going to banana plug) is the correct arrangement to plug into the Zamp outlet on the T@B trailer? 
Or is the "powerpole connector" shown here different from the Anderson powerpole connector?