Solar Controllers?? (and more)

[2014 sierra]

in my opinion if your RV is operating everything on a 12V DC system, don't change it. I know a bit about electronics, I just am not that familiar with solar. just so you know it was the most troublesome thing for me to change a simple light bulb went it burnt out, yes I have been using a simple very small harbor freight solar power kit 45W to help maintain battery power when we have power black outs.


OK, now I am getting somewhere
things I can simply forget about using while on (ONLY) solar power;
-AC UNITS
-WELDER
-AIR COMPRESSOR


The things I am still questionable about;
- ELECTRIC HEATERS X3
-MICROWAVE
-KITCHEN AND BATHROOM APPLIANCES
-CIELING FAN AND VENT FANS
-hot water heater (it can be switched to propane.....)still would need DC power.


Things I think are ok to operate on regular basis on solar
-LIGHTS
-TV AND ENTERTAINMENT SYSTEM
-refrigerator I leave on auto / yes or no? or should I manually switch it to lp while on solar?


Is this it? This is pretty much what I can do without solar and a cheap inverter I already have, I was seriously hoping I could get 100% solar so that I could run from 6pm to 8 am at 100% efficient (not burning fuel, working on anything or causing any noise outside) just a quite evening having dinner watching some TV sleeping, getting up, get cleaned up have some breakfast and then turn on the generator.


So now the question is, can I do this? and how many of the questionable items I listed would I be able to use?


Thanks

[SidecarFlip]

Having read all this and being very corn fused.... I'm glad I have an Inverter genny and a gas can to fill it with.

Seems like a lot of hoopla just to get a sun tan.

[stevejahr]

Originally Posted by 2014 sierra

...OK, now I am getting somewhere
things I can simply forget about using while on (ONLY) solar power;
-AC UNITS
-WELDER
-AIR COMPRESSOR

This is a start to getting real
Definitely add to this list ELECTRIC HEATERS X3

Originally Posted by 2014 sierra

The things I am still questionable about;
- ELECTRIC HEATERS X3
-MICROWAVE
-KITCHEN AND BATHROOM APPLIANCES
-CIELING FAN AND VENT FANS
-hot water heater (it can be switched to propane.....)still would need DC power.

Hot water heater definitely goes on propane only.
Refrigerator goes on propane only.
Define KITCHEN AND BATHROOM APPLIANCES: if they generate heat they become a stretch for solar pretty quickly. Hair dryers are an example of a bathroom appliance you will want to run on generator if you can.

Originally Posted by 2014 sierra

Things I think are ok to operate on regular basis on solar
-LIGHTS
-TV AND ENTERTAINMENT SYSTEM
-refrigerator I leave on auto / yes or no? or should I manually switch it to lp while on solar?

Lights should be fine, especially if they are LEDs. TVs these days are relatively low power and should be fine. Already covered refrigerator. Add water pump should be fine (low duty cycle).

It is possible to handle the built in propane RV heater on solar.

Originally Posted by 2014 sierra

Is this it? This is pretty much what I can do without solar and a cheap inverter I already have, I was seriously hoping I could get 100% solar so that I could run from 6pm to 8 am at 100% efficient (not burning fuel, working on anything or causing any noise outside) just a quite evening having dinner watching some TV sleeping, getting up, get cleaned up have some breakfast and then turn on the generator.

You can do this but may need to modify your lifestyle a bit is the point. Your RV is not like a grid connected home so some of the solutions are a bit different. And you have to be more aware of consumption and systems operation to make it work. But it can work.

I have a starter system on my TT with only a single 100W panel with 20A PWM controller and the dealer provided 12V group battery. Very basic. It is sufficient for summer time boondocking. The next level of upgrade for me is to add another 100W panel and a second battery. This would allow me to support the propane heater. All presuming good solar conditions - any shade or clouds and all bets are off. I just acquired a Honda EU2000 generator as backup

I have grid connected solar on my house... we went up one step above what was recommended and in the spring and fall our meter runs backwards. We spend that and a bit more during the winter and the really hot periods in summer. My records show that energy production of solar varies quite a lot depending on month of the year. On sunny days I get a peak of ~30kWh in April - Jun and taper to ~25kWh by the end of August. It drops down to a low of ~15kWh in Dec - Jan, but only on the sunny days. My actual runs much lower due to winter weather and clouds. I mention this to highlight the limitations of solar: A) it does not always work and B) when it does work it does not always work as much. So when considering solar also factor in when and where you are going to camp and be realistic about how well solar will work then and there.

[Bluepill]

From the Samlex website:

As mentioned, PV / Solar cells are wired in series and in parallel to form a PV / Solar Panel (Module). The number of series cells indicates the voltage of the Panel (Module), whereas the number of parallel cells indicates the current. If many cells are connected in series, shading of individual cells can lead to the destruction of the shaded cell or of the lamination material, so the Panel (Module) may blister and burst. To avoid such an operational condition, Bypass Diodes are connected anti-parallel to the solar cells as in Fig.7 As a consequence, larger voltage differences cannot arise in the reverse-current direction of the solar cells. In practice, it is sufficient to connect one bypass diode for every 15-20 cells. Bypass diodes also allow current to flow through the PV module when it is partially shaded, even if at a reduced voltage and power. Bypass diodes do not cause any losses, because under normal operation, current does not flow through them.

A friend with a residential 32 panel system claims that partial shading of any panel does NOT shut that panel down completely - it just reduces the output.

Anyone know about this series/parallel and bypass diode panel technology?

[2014 sierra]

Originally Posted by SidecarFlip

Having read all this and being very corn fused.... I'm glad I have an Inverter genny and a gas can to fill it with.

Seems like a lot of hoopla just to get a sun tan.

Yaaaa, the idea here is to burn less fuel save costs and do a bit to help our environment.....wow, did I just say all that out loud, how dare I......lol

[ScottBrownstein]

BluePill
Bypass diodes are required in any solar panel that is sold in the US. They are not designed for performance improvement but for safety reasons to avoid overheating the shaded cells and potentially causing fires. However, a nominal 12 volt panel might have 3 bypass diodes only (for cost reasons) and this can actually increase the losses from partial shading, since the diode will "take out" far more than the actually shaded cells. It is true that partial shading does not reduce the panel output to zero, but it has a much larger effect that the simple area proportion of the panel that is in shade. Under some conditions, bypass diodes can improved shaded performance, but it will depend on the nature of the shadow and the physical design of the panel. Moral, take out multiple cells in one diode's string and leave the other strings in full sun, this means shade the long dimension of the panel...not the short one if you can, but that could require some big tree pruning shears and moving your RV.

[aeblank]

Yowzers. Lots going on in this thread. Too much to bother quoting the specific replies.

Thanks for the additional solar panel info. One thing I've noticed is that any PWM controller basically says it'll limit the power down to 30A, even if more is available. So I suppose that alleviates any concern about under-sizing (other than the lost efficiency). The victron stuff I was looking at was pretty sweet, after adding current monitoring to it. Bluetooth visible, 30 day logging, etc. However, I think you've probably convinced me to simplify and save some money. The bogart controller/monitor do seem pretty nice in combination. I'll continue to poke around. I naturally like the whiz bang of the victron.

Regarding the hair dryer....yup, it's some juice, but only for a couple minutes. It, along with the overall convenience, is what's opening the checkbook.

Regarding the lithium-iron batteries.. Man, it'd be nice, but not this round. While I'm a lucky guy and don't have to pinch my pennies (I of course try to get the most bang for the buck), I do need to pinch my dollars. I have a light weight trailer and a heavy duty truck, so the weight matters none to me. The deeper draw is nice, for sure. Perhaps next round, as batteries are essentially a consumable.

Regarding my thread piggy-backer (said fondly, as it doesn't bother me at all)... I say burn propane, so what. It's clean burning (if you're hippie concerned) and it's quiet. Why on earth would you run a generator (or spend thousands on solar) in order to run an electric heater. Even in a permanent setup (house) people don't do that, they burn propane. So don't have any guilt about it.
Also, as a frame of reference........15 or 20 years ago (ok, ok, 20 or 25years) when I camped with my parents. We had a couple "decent" batteries (decent in quotes because they were crap compared to the Trojans). We'd camp for the weekend with NO solar and NO generator in late October in MI. Propane water heater, propane fridge, propane furnace, 12V water pump, 12V (TUBE!) TV, and all the lights we wanted (non-LED!). We camped all weekend, every weekend like that (friday night thru sunday night---no leaving early sunday for us). Sure, no hair dryer and no microwave. Still, it was a complete camping experience.

What kitchen appliances? You obviously have more *room* to take appliances than we do (haha). The stove/oven should do everything you need. If you want drinks, perhaps blend up some ice before you go or something. Minimizing needs is the easiest way to make it possible. I know, I'm one to talk.........I'm very nearly putting in a 2k inverter for a hair dryer.

[aeblank]

Thread is pretty much done, but it's mine, so I'm going to add more questions...

With my layout, it makes sense to put all the equipment (inverter with transfer switch, charge controller, etc) about mid-span on the trailer. Naturally, the battery(ies) are in the front, on the hitch. As such, I'll be running something like #3/0 cable from the batteries to the inverter.

I'd PREFER to NOT run separate cabling from the charge controller to the batteries. I'm wondering if there would be any issues with connecting the controller to the #3/0 cable.

I can see where it *might* confuse the charge controller when the inverter is on. I'm not even certain of that though, as the inverter will have an effect on the batteries no matter where things are connected.

I also may well get less voltage drop on my #3/0 cable than on a dedicated feed that I run. For sure that is true when the inverter is off.

I also think that I know that some solar panels are wired directly into inverters, without batteries at all. So what's the harm in my proposed wiring.

Just looking for thoughts and reasons for them. I have an email in to victron to ask them, but they thought I said 15 meters of cable, instead of 15 feet.

[PSU Turf]

Don't you need the charge controller wired between the solar panels and the batteries? I am not an electrician but as I understand it the wiring has to go from the solar panels -->charge controller-->batteries-->loads. If it is not wired in that order how do you control the amount of voltage charging the batteries?

[aeblank]

The end of the large cables is the same as the battery.

[PSU Turf]

Got it. Can you connect a cable that big to your charge controller without cutting off some of the wire strands? The biggest I could connect to my Bogart charge controller is 6 gauge.

[aeblank]

Originally Posted by PSU Turf

Got it. Can you connect a cable that big to your charge controller without cutting off some of the wire strands? The biggest I could connect to my Bogart charge controller is 6 gauge.

Probably not. It'll be #3/0 to the inverter lugs, and short cables (6awg perhaps, like you say) from the charge controller to the inverter lugs.

Perhaps an intermediate connection block, depending on the exact setup of all the components. It's all the same, electrically.

[stevejahr]

Should be fine connecting charge controller to the same lines that feed the inverter. This is basically how I have mine setup. I needed to run a ground cable all the way back too so I could insert the current measurement shunt. Only difference is "all the way back" is the front storage compartment on my TT so not quite so far. Do make sure that you size the cable an extra size or two up from the basic size required for the current so you avoid voltage loss over the long cable run.

Note that you will want to make sure there is some kind of circuit protection up front near the battery to protect those big cables against short circuit overloads.

[aeblank]

Originally Posted by stevejahr

Should be fine connecting charge controller to the same lines that feed the inverter. This is basically how I have mine setup.

I sure thought so, but it's good to know someone's doing it.

Originally Posted by stevejahr

I needed to run a ground cable all the way back too so I could insert the current measurement shunt.

I, too, will be having to do that. $3 or $4 a foot. Oh well....it's only money.

Originally Posted by stevejahr

Do make sure that you size the cable an extra size or two up from the basic size required for the current so you avoid voltage loss over the long cable run.

Of course. Though, the inverter is way over-sized for the loads I expect, so the cable will be doubly over-sized.

Originally Posted by stevejahr

Note that you will want to make sure there is some kind of circuit protection up front near the battery to protect those big cables against short circuit overloads.

Yeah, 200A fuse. No biggy....
Oh wait, it actually is no biggy.. http://a.co/aV3oAof

[2014 sierra]

Originally Posted by mikestahoe

If money is no object...you might want to consider moving from the typical flooded (Trojan) or
gel filled battery to the newer LiFePo storage batteries. Less voltage sag, resistant to partial charge deterioration, 2-3x the life, lighter weight per Ah plus 80% discharge is acceptable. With the types of loads being discussed (welder, air compressor etc) LiFePo will provide a much higher instantaneous current with no damage. I've also "heard" that they are more efficient on the charge side e.g. charge more quickly but I may stand corrected on that attribute. Cost about $1600/200 Ah.

OUCH........
I know that the Batteries are what the world go round with solar, for just a few reasons.
1- you need something that has a high ah rating
2- you don't want to go bankrupt buying it
3- they need to handle the high charging rate
4- the longer the warranty the better

so I think everyone on this thread already knows that two 6 VDC FL batteries are better for this application than one 12 VDC battery.

I CURRENTLY RAN INTO 3 IMIDIATE ISSUES WITH MY CURRENT DESIGN.

1 - Battery Pack Weight ( Approx. 463 lbs.) and RV Weight distribution (originally I was planning to convert a front cargo bay in my 5 th Wheel to a Battery storage bay) after adding the weight from the solar system and new generator together I would put an additional Approx. 1000 LBS on the truck bed. (not happy) so I found a place to put the batteries behind the trailer axles to help offset the generator weight I am adding to the front.

2- possible voltage drop running the cables approx. 30 ft. from batteries new location to inverter and controller to batteries (is it doable?)

3) the new location will have a lot more exposure to direct sun on the box. higher heat absorption. however will be well vented. I attached an idea of mine.



any ideas or comments will be appreciated. thank you

[aeblank]

I can post a chart for wire capacities Monday. There is a wire that can do it, whatever "it" is... That said, is your bumper strong enough?

[2014 sierra]

Originally Posted by aeblank

I can post a chart for wire capacities Monday. There is a wire that can do it, whatever "it" is... That said, is your bumper strong enough?

that would be great and solve one issue for the voltage drop. what about the heat?

my bumper is welded to the frame, I am going to fabricate a new bumper to extend out approx. 10 inch's, and attach it to the original bumper. this way the box will have full support from both bumpers holding it up. and the bumper will then extend past the width of the box again protecting the RV and newly installed box / battery pack.

so with the properly sized cables / wiring, weight more evenly distributed, I just might have found my solution. I just need to hear about the heat issue.

thanks.

[aeblank]

My dad mounted the generator on the back. Is that a possibility? Though, I don't see heat being any worse on the back than on a hitch, like mine....

[2014 sierra]

Originally Posted by aeblank

My dad mounted the generator on the back. Is that a possibility? Though, I don't see heat being any worse on the back than on a hitch, like mine....

Thank you for that jump start to get my wheels (in my head)spinning again.

The Generator; This 5th Wheel RV was built with a Generator bay included
so to put it other than its designated spot would kind of defeat the purpose of the RV design.

The Batteries; you brought up a valid point, there are batteries mounted on the Tung of trailers all over. that would make you think it should be fine. the question is, are those batteries used for solar power? I know for sure it is written that solar panels loose efficiency with heat I just didn't remember if the batteries also lost efficiency with heat. especially being in an aluminum box in direct sun light., I guess I could install 2 vents, 1 on each side for better ventilation.

[2014 sierra]

Originally Posted by PSU Turf

Don't you need the charge controller wired between the solar panels and the batteries? I am not an electrician but as I understand it the wiring has to go from the solar panels -->charge controller-->batteries-->loads. If it is not wired in that order how do you control the amount of voltage charging the batteries?

Thanks, I think I see what he is driving at, the inverter and the controller positive and negative hook ups are at the same terminals on the battery, so what's the difference in running 2 heavy gage cables from your batteries to a hook up point near the transfer switch (for example) and hooking up your inverter and controller to the remote hook up point instead of having to run 4 heavy gage wires directly at the batteries? I think if you only run 2 wires to have a remote battery hook up just be sure you increase the gage of the wire. (due to them carrying a larger load). wouldn't worry about the direction of current flow. Look at it like this..... your only extending the terminals off the batteries longer. the controller will support the inverter till the inverter is no longer demanding a load then the controller will charge the batteries. is this what you were tying to figure out?