Too much solar????

Normfun

Is it possible to have too many solar panels?  I have one 100 watt portable.  This works great on mostly sunny days.  This past trip we spent 3 wet dark days out camping (loved it)  anyway the solar barely did anything.  about 1 amp of charge was all we were getting.  So we lost about 10-15% of the batter charge each day.  I am thinking about adding two flexible 100 watt panels to the roof as a full time solution then wiring in the portable as a boost when its really dark and shady.  All would go in to one controller.  I think this will work great in the shade and rainy days but will I over do it on sunny days?  Do I need to be able to kill a panel in full sun?  Or will the controller just do its thing and not overcharge the poor battery?  The other worry is do I need to cut out either the solar or the tow vehicle from charging when driving?  I wouldn't want voltage feedback  burning up anything.  

I am probably overthinking this but, that's what I do 

Thanks for any input.

jkjenn

It depends on your controller. Each controller will have a max input value.

Nomad

Ahhhh, those rainy days - I've had many this last month, that's why I have the generator. Might be cheaper than adding all that solar. If you don't need to run the air conditioner you could get a smaller 1000w. If air, they recommend 2000w but someone here in the forums said they were running the air with a 1000w with no trouble.

Verna

Norm, how many amp hours (ah) is your battery?  I will have 264 ah with two 6-volt golf cart batteries and 200 watts of solar panels.  I understand you want the watts close to the ah of the battery.

I had problems two different times last winter in AZ with not enough sun and not enough charging.  I currently have a 100 ah battery with an 80 watt solar panel.  Two cloudy, rainy days in a row and I had to run my Tacoma for an hour to get the charge up around 12.20, and then I disconnected everything that was taking juice from the battery overnight.  The sun came out the next day. 

The 2nd time I wasn't getting a charge and only saw it late in the day.  I did some trouble shooting and couldn't figure it out.  Once again, I ran the Tacomoa to bring the battery charge up and unplugged everything.  I started with a fresh mind the next morning and found a blown fuse on the Zamp solar panel (better look at the fuse because it is not a common one--I found that Jeep's use the same small fuse, borrowed one, and went out and found some and replaced his).  As soon as I replaced the fuse, the battery started charging. 

So, I understand why you want more solar panels, but you need the battery/batteries large enough to accept the charge.  The controller will only allow the batteries to go to their maximum charge and then it stops allowing the solar charge to go to the batteries so they won't be overcharged. 

As Jenn stated, there are maximum amps that each controller allows.  You'll need to do some research to see how many amps (30 amps, 20 amps?) you need for the controller to have for 300 watts of solar panels.  I skipped that part of the research, saving it for later......sorry.

PXLated, yes, a generator would be nice at times such as those two days, especially the Honda you have. 

Nomad

I rarely had to used the generator until this last month - The southwest was sunny most the time so my Zamp120 was fine. And of course there always the option of fleeing to a campground with hookups till the rain subsides. I hit a couple of COEs in Kansas (fairly big campgrounds) and it was just me and the host in either - had my own private lakeside campground :-)

mash2

Jenn is right on the controller.  There should be a max PV input power in the controller manual.  I have a Tracer 2215 MPPT and it has a max PV input power of 12V/260 watts.  In my case, I keep 136 Watts on permanently (installed on roof), and add a third panel (another 68 watts) when I feel the need.  Couldn't add two panels because it would overtax the controller. 

Normfun

Thanks all.  The 30 amp controller will handle the 200 watt normal and 300 watt sometimes load as it is rated at 360 watts in.  

Verna you bring up a good point about the battery. It is just a lowly 75 ah battery.  Hmm maybe upgrade that one first and see how I do?  

We don't have a ton of draw even on rainy days. I have everything unplugged or on a  switch.  The only draw is the Alde, a light, and the USB ports charging a phone at night.  I figure about 12 amps a day is  all we are using but the solar was only putting in about 7 or so that weekend.  We were never worried and never got below 12.3 volts but.............  Hopefully this whole work thing will end someday and we can travel on longer trips 

Any ideas on the permanent solar and charging from the vehicle as well while driving?  Would this cause a problem of voltage being fed in to an output of either the controller or the car?  

jcfaber1

I do not understand how they rate it a 30 amp controller if it only handles 300 watts.  300/12= 25 amps.  My MPPT controller(midnight kidd) will just ignore the overage if the incoming watts are too high with no damage.   And that's assuming that our panels are outputting at 100% which does not happen very often.  I highly recommend getting to 6V golf cart batteries wired in series for about 225AH, this gives you more days of drain before panic sets in.  That would be a better investment before you add more panels.

Verna

normfun said:

Thanks all.  The 30 amp controller will handle the 200 watt normal and 300 watt sometimes load as it is rated at 360 watts in.  

Verna you bring up a good point about the battery. It is just a lowly 75 ah battery.  Hmm maybe upgrade that one first and see how I do?  

We don't have a ton of draw even on rainy days. I have everything unplugged or on a  switch.  The only draw is the Alde, a light, and the USB ports charging a phone at night.  I figure about 12 amps a day is  all we are using but the solar was only putting in about 7 or so that weekend.  We were never worried and never got below 12.3 volts but.............  Hopefully this whole work thing will end someday and we can travel on longer trips 

Any ideas on the permanent solar and charging from the vehicle as well while driving?  Would this cause a problem of voltage being fed in to an output of either the controller or the car?  

Norm, your problem is your battery.  I priced two Interstate 6V golf cart batteries wired in series, 264 ah, for a bit over $300.  The Interstate guy said he could make battery cables to the length that I need.  They weight between 60 to 70 lbs each, so it will add the equivalent weight of one more battery on your tongue.  I haven't seen the bottom of the box on a T@B's tongue, but I'll bet you could have a welder weld a platform for the batteries.  Be sure to read Lisa33's how-to on the LG forum on how she had to rearrange the inside of the tongue box on her T@DA to put the golf cart batteries in there.  She had to squeeze them in, and they're not square with the sides of the box, nor the front of the T@DA, but they are secure in place.

If you PM Lisa33, she'll be able to give you an answer on the permanent solar and charging from the vehicle while driving.  Hopefully she'll join this conversation because of her extensive knowledge on the solar power.

mash2

I would agree that a single battery probably is the initial weak link.  I went to two 12v parallel AGM batteries because I wanted to move them inside the t@b (over the wheel wells).  My setup is with one AGM over each wheel (reducing tongue weight).  I ended up with 200 amps distributed between the wheel wells with venting boxes.  I was concerned with tongue weight and wanted to lighten the weight a bit for the TV.  I had both mounted in the tongue box (built a pedestal for both next to propane) prior to moving inside.   It was tight, but both fit in the tongue box (Type 27's).  

Verna

mash2 said:

I would agree that a single battery probably is the initial weak link.  I went to two 12v parallel AGM batteries because I wanted to move them inside the t@b (over the wheel wells).  My setup is with one AGM over each wheel (reducing tongue weight).  I ended up with 200 amps distributed between the wheel wells with venting boxes.  I was concerned with tongue weight and wanted to lighten the weight a bit for the TV.  I had both mounted in the tongue box (built a pedestal for both next to propane) prior to moving inside.   It was tight, but both fit in the tongue box (Type 27's).  

Mash, do you have a picture of the inside of your tongue box with the two batteries before you moved them inside?  I'm just curious.  As I said, I've never seen the inside of the tongue box on a T@B. 

Verna

http://www.golittleguy.com/forum#/discussion/comment/40597 

This has pictures from Linda (Teardropin) who figure out what she needed with her solar and made a system that is working. She used two 6V golf cart batteries wired in series.

mash2

I'll check later today.  Not sure if I took picture of old setup.  

Verna

http://www.golittleguy.com/forum#/discussion/comment/40275

This has pictures of Lisa33's tongue box on her T@DA with the two Trojan 6V golf cart batteries in it (she says the T@DA's tongue box is the same size as the T@G and T@B).  Trojan is another name brand, just as Interstate is a name brand for batteries.

Lisa also says her controller is in the tongue box closer to the battery, which is the opposite of what I had read, but I know Lisa's set-up works well.  She has three 100 watt solar panels mounted permanently on her roof of her T@DA. 

jkjenn

Alternatively, you could go with something like  Goal Zero Yeti 150 or 400 and charge things like phones, cameras, and laptops off of it and run lights like their Light a Life off of it. You can charge those from 110v, your vehicle, or connect to a solar panel. But, if it is your fan, fridge, and lights that are killing you, an upgrade in battery and/or a generator are the solutions.

jcfaber1

Here is mine.  Note the vent is 1 inch copper with 1/2 inside to be the bottom of the box.  Also the solar charge controller is on the right.

Verna

http://www.golittleguy.com/forum#/discussion/1297/new-solar-installation/p1

Here is Lisa33's installation discussion of her 300 watts of solar panels, permanently mounted, with two 6V Trojan batteries wired in series.  Quite an undertaking, but it works very well.

Verna

jcfaber1 said:

Here is mine.  Note the vent is 1 inch copper with 1/2 inside to be the bottom of the box.  Also the solar charge controller is on the right.

JC, where is this located?  It looks like near a wheel well.  And, where can you buy a double battery box like that?

Normfun

Wow!  some great ideas!  I will need to crunch some numbers.  Right now I have a spare propane tank on the Tongue so that adds some weight.  Not too sure about replacing my batter @60lbs with 180 lbs that sounds like I might pull a wheelie at any moment   ok maybe not but definitely heavy.  

Nomad

Verna - Your links just take me to the LG forum home page -They don't look like they should but that's where I end up instead of the actual thread. Any idea why? Anyone else getting this?

jcfaber1

It is in the wheel well.  They are AGM batteries.  I had a local plastic company make it for me.  $150.  There is no reason to move it inside unless you have another use for the space.  I put a tankless water heater up front so that was my motivation.

Verna

I was wondering how this would be for non-LG members.  If you apply for a "membership", I know you'll be able to see them.  I can see them fine, so either it's my magic admin powers or it your lack of membership.

Norm is an LG member so he was able to the link on LG.

Michigan_Mike

PXLated said:

Verna - Your links just take me to the LG forum home page -They don't look like they should but that's where I end up instead of the actual thread. Any idea why? Anyone else getting this?

Give the link some time to load.   True, it appears that you're at the LG home page but Lisa's thread does eventually load up.  

Normfun

The links worked all too well for me.  This little project is going to take some work. Think I'll  bring the trailer home this weekend.

Nomad

Mike - Hit the link, waited 2 minutes, no go - How long does one need to wait?

Michigan_Mike

normfun said:

I am thinking about adding two flexible 100 watt panels to the roof as a full time solution then wiring in the portable as a boost when its really dark and shady.  

If I had a T@B that is exactly what I'd do as I like the flexible monocrystalline panels and the permanent means of mounting them.  I'm guessing that with an enhanced battery set-up (toward the back of the trailer) you should be good to go if you added dual, 100 watt panels on your T@B.  And do more research if you are considering an additional portable panel as I believe that they all have to be similar or an odd size panel could drag down the charging capability of the other two.  Many people do run panels in tandem and here is some information that might help you out some.  

mash2

Agreed. I got a third panel which is my boost;  all three are in parallel and I set up the third panel access off the permanent panel setup.  Just plug it into a splitter that is installed and I'm good to go.

hatbox

I have a question:  don't you have to wipe down the panels very frequently and wash them with distilled water to keep them optimally absorbing, and doesn't wind and dirt degrade them?  I'm in the dark on solar, but I thought you had to really stay on them.  How do you do that, and how long do they typically absorb and process efficiently when permanently installed in lieu of portable?  The zamp 120 is on my get list.

Nomad

Hmmmm - The Zamps are glass and really don't collect much - I wipe them down if it's been dusty otherwise all I do is fold/unfold. Can't see where there would be any other maintenance. The flexible panels obviously aren't glass so maybe they require something.

TabyDD

I am finding the 15 foot cord that comes with my 100w Renogy is too short any product suggestions on extending that cord.  I'm using the alligator clamps that came with the panels.  Apologies if I've asked this question previously.  DD

jcfaber1

I am using a 50 ft 8 guage marine grade cable.  I have MC4 connectors which attach to the PV on one end and a trolling motor plug on the other end.  From the female side of the trolling motor connector it goes to a breaker to the charge controller.  You need to look at the voltage drop and keep it under 3%.  Is your charge controller at the PV or close to the battery?  If you are using the suit case, then you would be @2.3% drop over 50 ft with the 8 gauge cable.  I would mount the CC close to the battery.