Info needed on a solar panel purchase

[Donnie]

Hello Team,  I'll be the first to admit that I am not up to speed on the latest solar panels..even though I have had passive solar heat "hot air" collectors on my shop since we started homesteading here in the late 70's.  Thanks to John Shuttleworth of Mother Earth News.  Any way, I need to get some opinions on the best 100 watt panel to buy for  one of my Chinooks. I need to keep my aux. battery charged to run my small 12volt frig.  while I am camped at a festival for 3 or 4 days..  I would like to get something in the $100--to--$150 dollar range.. I am confused by the assortment of panels on line..  I will build a frame to mount it, so I can place it in the sun while camping under a tree if possible... plan to also build the rack holding the panel on a base that can follow the sun using a timer & a small motor to rotate it so I will not have to keep moving it thru-out the day..if anyone has any thoughts or opinions on this.......I would like to hear them....I have just narrowed my search on line down to about 40 or 50 panels. BIG LAUGH  

All opinions welcome.............. thanks, Donnie

[zero]

42 minutes ago, Donnie said:

Hello Team,  I'll be the first to admit that I am not up to speed on the latest solar panels.. thanks, Donnie

Very little has changed in the past 30-40 years except prices. Not much "new" to know. I've got a few  old Arco panels I got 35 years ago that still work fine.  If you sort through all the advertising hype - only two things have really changed.  One is the solar cells are closer together so in an assembled "panel" - you get more watts per square inch.  Two - all solar panels I know of now have built-in blocking-diodes.  30 years ago many did not.  

New panels usually are 9-10 square inches per watt (30-40 years ago many were 20 square inches per watt)

New panels have blocking diode so they won't drain a battery with reverse current when the sun stops shining

New panels usually are protected with tempered glass (unlike plastic on many 30-40 years ago).

I suggest you buy whatever is cheapest - shipped to your door.  I think right now Renogy is one of the best deals.

I just bought a set of four Renogy 100 watt panels with all the roof mounts, 30 amp controller, and all the wiring for $601  shipped to my door from Amazon.
Just the bare panels would of cost me around $1.20 per watt including shipping.  Ten years ago the cost was $5.50 per watt.

[jmowrey]

We also kept our panel free floating, not roof mounted, so we could track the sun with it. It's great. We get full advantage of the sun when parked in the shade. In addition, we used a dual controller (controls two battery connections instead of just one) then wired the panel to the vehicle battery as well as the coach battery so we can use the panel to trickle charge both batteries during the winter months. This has worked out great for us. No need to remove batteries or worry about them during the winter. The controller allows for adjusting how much charge goes to each battery. When we are on the road and camping we set it to give 100% to the coach battery. During the winter, we split the charge between the two batteries.

[payaso del mar]

there's another thing that's changed besides what JD listed:  the prevalence of grid tie systems and 400-volt Li batteries has resulted in most new panels being a hell of a lot more than the old 17-19 (to charge a nominal 12) volts......a lot of em are 30-37 volts or more.  this won't be as much of an issue in the small size panels you're looking at, but if they're higher voltage panels, be sure the charge controller you buy is able to turn their output into 12v. 

the current crop of MPPT charge controllers also can make use of that "excess" voltage between 12 and the 17-19....with the old style PWM (pulse width modulation) contollers, that excess voltage was just a "cushion" and mostly went to waste.  remember the equation watts = amps x volts?  MPPTs invert the "X" number of amps at 19 volt DC into AC, then change it back to a larger # of amps at 12 (or whatever you're running) volts DC.  an MPPT controller might be worth it for you if you camp in cold weather a lot, as that's when you get the highest voltage from your panels and thus the most gain from an MPPT controller.

that said, solar panels can be a great thing to buy used.  they rarely "fail", just slowly degrade over time (20+ years), and you can test the output before buying..  for our cabin, I just got 12 panels totaling 2.8 kilowatt/day even at current degraded output for $40/panel. check your local CL.  if you do get used panels, be aware that as JD noted, they may not have back-current blocking diode.  most charge controllers will perform that function, unless you buy the cheepie $40 NPower unit from Northern Tool.....ask me how I know this!

not sure a 100w panel is going to keep up with a fridge unless you have a very efficient fridge.

I've done panels both ways:  on the roof, and free standing with legs.  the free standing approach has lots of merit but consider:  1) stowing it while enroute.  2) theft issues.  3) securing to ground so it doesn't get blown over and shattered in sudden breeze and 4) voltage drop on 12V will require relatively heavy wire to get it more than a few feet from toyhome.  I think the best of all worlds would be to have one on the roof AND a bigger auxiliary free standing one that could be plugged in via an external 12v outlet when boondocking for extended period.  you just wire an outlet to connect to the INlet side of the wires from panel to charge controller 

remember that if your Chinook is one of the poptops, you'll be hoisting the weight of any panels you put on the roof every time you set up camp.  for this reason, I did a lot of searching for mine to find the most watts per pound, and just ordered one of the 24lb. Vikram 150W panels from Backwoods Solar. 

[payaso del mar]

in the irony of ironies, all this high tech, power-from-the-air stuff is shackled by having to rely on lead-acid battery storage technology dating from I think the 1800s,  I can hardly wait til lithium batteries get more common/affordable/bugs worked out........not that we'd need the 6+ gigawatts Tesla claims.  but every time I tell my 22R about how one day it won't have to tote all that lead, it asks me, "How long, daddy?"

[bobblefrog]

That Vikram is less than three and a half square, too...not bad at all.  Thanks for pointing that out.  Look forward to hearing how it works.

[zero]

12 hours ago, payaso del mar said:

in the irony of ironies, all this high tech, power-from-the-air stuff is shackled by having to rely on lead-acid battery storage technology dating from I think the 1800s,  I can hardly wait til lithium batteries get more common/affordable/bugs worked out........not that we'd need the 6+ gigawatts Tesla claims.  but every time I tell my 22R about how one day it won't have to tote all that lead, it asks me, "How long, daddy?"

From what I've seen - the Lithium batteries weigh around 60% of what conventional lead-acid batteries do. A significant gain I might pay for if I had a space ship or a race car.  In my RV?  If a person has just one "house" battery - that means a savings of 20 lbs. and if two, a savings of 40 lbs.  That tiny gain for a HUGE cost.  To me. cost per amp-hour, on an annual basis is all that counts.  I figure I will be buying batteries forever so that is how I figure them.  Old fashioned FLAs (flooded lead-acid) are still, by far the most cost-effective.  I wish I could go back in time instead of forward.  10 years ago I could buy Trojan T-105s for $50 each.

[zero]

15 hours ago, payaso del mar said:

Vikram 150W panels from Backwoods Solar. 

GREAT place to do business with.    I got a lot of solar equipment plus my Sundanzer DC refrigerator from them. I'm glad to hear they are still around.

[zero]

I  just bought a bunch more panels -all  Renogy 100 watters.   Backwoods wanted $154 each shipped to my door in Michigan for the Vikrams.   I got the Renogys shipped to my door for $130 each if one at a time. Cheaper for quantity. 

Vikram weighs 18 lbs. and measures 45.4" X 26.2" X 1.34"    11.8 square inches per watt, and 5.5 watts per pound.

Renogy weighs 16.5 l bs. and measures 47" x 21.3" X 1.4".  10 square inches per watt, and 6 watts per pound.

[Totem]

I just picked up 4 interstate golf cart batteries for my backwoods Michigan cabin from Costco for $80 each... the manager told me they are made by same company as Trojan... not sure if that's true but hey for $80 each and matching 2016 date codes I was all in.

I'll be taking out the 3 fishing batteries That I have there now and taking the best two from that set to put into my rig. One advantage of the deep cycle marine batts; they can start the toy home in an emergency; not sure how easy that would be with a couple 6 volters

Edited April 5, 2016 by Totem

[Totem]

On ‎4‎/‎5‎/‎2016 at 8:18 AM, jdemaris said:

I  just bought a bunch more panels -all  Renogy 100 watters.   Backwoods wanted $154 each shipped to my door in Michigan for the Vikrams.   I got the Renogys shipped to my door for $130 each if one at a time. Cheaper for quantity. 

Vikram weighs 18 lbs. and measures 45.4" X 26.2" X 1.34"    11.8 square inches per watt, and 5.5 watts per pound.

Renogy weighs 16.5 l bs. and measures 47" x 21.3" X 1.4".  10 square inches per watt, and 6 watts per pound.

I got a guy out of florida that has 120 watt panels made in the USA for $120 shipped free to your door. no mounts though.

Edited April 15, 2016 by Totem

[zero]

1 hour ago, Totem said:

I just picked up 4 interstate golf cart batteries for my backwoods Michigan cabin from Costco for $80 each... the manager told me they are made by same company as Trojan... not sure if that's true but hey for $80 each and matching 2016 date codes I was all in.

I'll be taking out the 3 fishing batteries That I have there now and taking the best two from that set to put into my rig. One advantage of the deep cycle marine batts; they can start the toy home in an emergency; not sure how easy that would be with a couple 6 volters

As far as I know - Trojan does not rebrand batteries for anyone.  Interstate branded batteries are mostly made by Johnson Controls but I bet the GC2 batteries like you got are made by Deka. The last set I bought from NAPA (Dekas) lasted me 8 years.  I am looking right now for a set of 6 volt golf-cart batteries to use in a new cabin I have in the UP.  Never been to a Costco in my life.   I searched around and found Duracell batteries at Sams Club for $85 each.  Duracell brand is also made by Deka.  There is a Sams Club in Traverse City.  That will be a 260 mile round trip plus I have to pay $50 for a membership.  So I am still debating whether the trip is worth it - or to just go my local Walmart and buy the type 29, 12 volt marine batteries for $86 each. I know they are not as long-lived as the golf-cart batteries - but . . 

[zero]

1 hour ago, Totem said:

I got a guy out of florida that has 120 volt panels made in the USA for $120 shipped free to your door. no mounts though.

That is a great deal.  Shipping is often the deal-killer.  I used to buy all my solar equipment from Sun Electric in Miama, Florida. But they no longer ship UPS and want to do truck shipping so the transport prices are too high unless I buy pallet loads of panels.  Who is this seller? I assume you mean 120 watt and not 120 volt.

[payaso del mar]

yeah, I really like Backwoods....been doing biz with them for 25 yrs, since they were owned by Steve and Liz Willey.  they are focused more on off-grid systems than on grid-tie stuff, which is more why I do solar in the first place.

boy is that true on the shipping.  that's one reason I recently looked for used panels locally.  I once ordered a 110w panel and found that the shipping would be as much as the panel......but to ship two identical ones didn't add one dollar to the shipping so I bought two.

Totem, if your 6 volt batteries are already wired in series to get 12 volts, you can jump off them just fine.  just connect the jumper cables in series just like the batteries are wired.  or run a heavy wire (2-4 ga)  to your combiner so you can just flip the "connect all" override switch to create your own jumper between the starting battery and the house batteries.. 

[Donnie]

Thanks to all of you for your replies... i have narrowed my search down to two suppliers... Renogy & Windy Nation.. The panel I want from Renogy comes with a POSITIVE ? ground controller...This has just added to my confusion as most vehicles that I am aware of are negative ground..??   I guess I should join a SOLAR forum & educate myself as I have avoided photovoltaics  long enough.....  My auto career is long in the past & I may have enough brain cells left to adventure into the present...  Next thing I'll be loading my cabin roof with solar panels...BIG LAUGH  very do-able now that my need for electricity is severely diminished..

Could be fun.... once I get this positive / negative thing under my hat.....admitting that I know $quat about this topic....  eating the humble pie,  Donnie

[payaso del mar]

i'm not laughing.....off the grid and off the radar = freedom from a lot of poop.  kind of ironic that this durty fogging heepie technology is now allowing all the other govt skeptics, right and left wing, to cut their dependence on govt and the grid...   equally ironic that my first solar panels came from that enviro leader, BP....25-30 yrs old and they still put out.

I've never heard of positive ground PV stuff.  is it British? 

 

 

[WME]

Neg ground rom Renogy, http://www.ebay.com/itm/Solar-Panel-100-Watt-12V-PV-Off-Grid-system-Kit-100W-Watts-Poly-RV-Boat-/271735143866?hash=item3f44ad3dba

The set I got from Windy Nation worked on my neg ground system

[Totem]

On ‎4‎/‎5‎/‎2016 at 1:05 PM, jdemaris said:

That is a great deal.  Shipping is often the deal-killer.  I used to buy all my solar equipment from Sun Electric in Miama, Florida. But they no longer ship UPS and want to do truck shipping so the transport prices are too high unless I buy pallet loads of panels.  Who is this seller? I assume you mean 120 watt and not 120 volt.

yeah typod volt for watt. let me look him up. brb

[Donnie]

On 4/15/2016 at 8:30 PM, payaso del mar said:

i'm not laughing.....off the grid and off the radar = freedom from a lot of poop.  kind of ironic that this durty fogging heepie technology is now allowing all the other govt skeptics, right and left wing, to cut their dependence on govt and the grid...   equally ironic that my first solar panels came from that enviro leader, BP....25-30 yrs old and they still put out.

I've never heard of positive ground PV stuff.  is it British? 

 

 

Here is the link to the positive ground panel..    http://www.ebay.com/itm/Renogy-100W-Watts-Solar-Panel-Kit-100-Watt-Poly-Off-Grid-12V-RV-Boat-Home/301339751896?_trksid=p2060778.c100276.m3476&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140725133649%26meid%3D6ddfe9141d484112a3e17e12d4fcf96f%26pid%3D100276%26rk%3D1%26rkt%3D2%26mehot%3Dpp%26sd%3D151690266358

[payaso del mar]

I dunno.  I don't see the logic of introducing a positive ground PV system into a vehicle where everything else is negative ground.  for starters, you wouldn't be able to also have your house batteries charge off the alternator.  this might be fine for a small cabin setup where you didn't have to deal with the incompatibility issue...not a bad price for 100W panel and a 30A charge controller......but i'd spend a little more and get a system that would talk more happily to the rest of my RV.

am I llena de caca again?  anyone else have any thoughts?

[Totem]

basically don't ground it (the controller). should work fine. Its not the panels that are negative ground; its the controller.

At least that's how I read it. Better yet ditch that crapola controller and get one off amazon for much cheaper and just get the renogy panels at $109 delivered from ebay.

[payaso del mar]

add me to that chorus.  crappy charge controllers are a headache.  a good quality one can be had for about 100, or even less.  look at the MidNite Solar Brat (30A, $89), or the Morningstar Sunkeeper, sunlight, sunguard, and sunsaver series models.  http://www.wholesalesolar.com/charge-controllers

I've also been pretty happy with the BAttery MINDer SCC180 I installed on the P-Roamer.....charge controller and desulfator.  it's 16 amps at 12 volt rated, so you might be able to get more amperage capacity for $100.  but it seems to do what they claim as far as helping rejuvenate sad batteries.....the sorely abused deep cycles I installed in it are now holding a charge at higher voltage than they ever would before.   http://www.northerntool.com/shop/tools/product_200365182_200365182

[Totem]

wow that's way to $ for me... I went with this one when my last cheapo Chinese one died....

http://www.amazon.com/Sun-YOBA-Switch-Charge-Controller/dp/B00PVOC11G?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

[Totem]

as far as desulphating, I am of the school its a job and then done the best it can be; hence you would not want that on there too long 4-6 weeks tops.

I use these sometimes when sulphation is suspected.

http://www.wizbangplus.com/

 

[payaso del mar]

pretty good price for 20 amps.  and I love the Chinese English:  The design of controller is small and exquisite,beautiful and generous.

[Totem]

I like them and also the crappy screw down terminal ports that take somehow the exact same screws from a car amplifier.. which comes in handy when I lose them.

My last one lasted for 4 years and then died after lightening strike. I don't ground my setup at the cabin.

[Donnie]

Still undecided on solar panel : going to go with Renogy, but have a question............MONO or POLY,   which is better & why?  for my Chinook / boondocking application..if you want to go into details I am paying attention.   Or what should I avoid & why?

I haven't made up my mind yet..........  thanks in advance for any & all advice     Donnie

I can't really find the answers to these queries  from the company/ seller..... I'm pretty sure that they are very honest, but one person told me that they are the manufacturer............ another told me that they buy from other suppliers.  I asked for the COO    & got a mumbo jumbo reply  ...many countries ?????

[WME]

Mono= Higher output per sq ft, cost more, partial shading makes a BIG reduction in out put, better preformacce in heat.

Poly is about total opposite.

[zero]

On 4/23/2016 at 9:43 PM, Donnie said:

Still foundecided on solar panel : going to go with Renogy, but have a question............MONO or POLY,   which is better & why? 

You are overthinking all this. There is very little difference between mono and poly panels in the real world. If you take two panels the same size and the poly is rated 100 watts, the exact size in mono might be rated 105 watts;  Do you really care?  They all have blocking diodes and all have shade problems. All that counts to me is price per watt at my door.  As far as "positive-ground" controller? Who cares.  Works fine with the negative-ground system in your Toyota. A rolling motorhome has no real "ground" anyway.  Just keep the solar-panel input part isolated.

The last set of panels I bought (a few weeks ago) was four 100 watt units from Renogy. Came with a "Wanderer" 30 amp controller. Model CTRL-WND30.  Has no "ground" connection. Just pos and neg input, and pos and neg output.

[zero]

On the subject of Renogy. I just got four more 100 watt mono panels for $550 shipped to my door. They measure 47" X 21.3".  The Renogy 100 watt panels in poly version are $10 each cheaper, and measure 40.1" X 26.3".   So the monos make 1 watt per 10 square inches, and the polys make 1 watt per 10.5 square inches.

[Donnie]

On 4/24/2016 at 9:19 AM, jdemaris said:

You are overthinking all this. .

The last set of panels I bought (a few weeks ago) was four 100 watt units from Renogy. Came with a "Wanderer" 30 amp controller. Model CTRL-WND30.  Has no "ground" connection. Just pos and neg input, and pos and neg output.

Interesting: last nite after looking at a lot of set up's...before reading this post,  I finally pulled the string on the Renogy 100 watt MONO kit.. It was 10 bux more than poly, but my choice was made on the the thickness of the panel ....since the less expensive was 3" thick & I am transporting it....I wanted the thin one...it also came with the Wanderer controller...10 gauge wire etc.   I know that I paid too much by purchasing a 'KIT". .....but for the 1st time I'm ok with it.

AS I learn, ask questions & read, I will be able to save some $$ by piecing together parts & pieces from different sources.. thank you ALL for your opinions.. 

....................Donnie

[Totem]

The simple answer to mono vs poly is more based in your weather. Thats because One tech DOES do better in cloud light than the other and one does better in sun. I prefer to use BOTH that way you can at least harvest some energy at better efficiency with some variance in weather if you are only solar and haven't also added wind.

[payaso del mar]

another consideration on type of panel is your mounting:  heat can be an issue on motorhome roof mounts if you don't allow a few inches clearance for it to escape. 

but really, JD's right, not much difference that you'd notice between mono and polycrystalline panels in a motor home size system.  the only thing to avoid, unless you need the rollability etc for a portable system, is thin-film panels, which put out WAY less per area than either mono or polycrystalline.

[Donnie]

OK TEAM, one last question..especially geared for those who are remotely sitting their panel in the sun while trying to park in the shade, or better said, not mounting the panel on the roof, but carrying it inside & setting up at your destination  How are you connecting the wires from the panel to your truck.?  I'm thinking about a receptacle of some sort or a trailer connector built into the body somewhere so I can just plug it in..   Also I want to use a more flexible wire than the one they sent me in the kit.. Yes it was a waste to buy the kit as the 20 feet of cable they sent is for a  permanent roof top installation & is WAY to stiff to fool with on the road.. I have ordered a 50 foot roll of 10 gauge wire that I can roll up & store in a drawer.......>>>>>>>>>>>>>  Any idea or thought's on this?    TIA,   Donnie

[WME]

OK this is a left field answer. Go to a large Hobby Shore that deals with electric model planes. The newer model will use 24 volt batteries at 100 amps. Ultra low loss connectors are used. Male, female, and bulkhead styles are made.