Ten pages from front. Ten pages from rear. Solar building

[John61CT]

Volts only become significant at the extremes. Measuring watts output, AH over the day will be more useful when A/B testing.

You definitely want to avoid even a twig's worth of shading though

 

[regis101]

I'm kinda hoping that panel voltage output is relative to watt and/or amp output. Perhaps it is.
Then I'll have to learn how and what the controller does with it.

 

[John61CT]

I'm kinda hoping that panel voltage output is relative to watt and/or amp output.

No, only at the extremes as I said. Voltage (think "pressure") ramps up long before amps (current flow, proportional at that point to watts) really climb with greater insolation.

Get a cheap clamp ammeter if your controller doesn't show amps.

Or a shunt-based battery monitor.

 

[regis101]

Oh man.  This solar stuff is great.  Why didn't yinz tell me sooner.?

Had a chance to play with it today.  Hot sunny day here in NorCal.  Had more amps coming in than going out with the one panel.

I'm using the Renogy 100 watt kit with an extra 100 watt panel as back up .  Using their Rover 20a MPPT.  The LCD display tells everything I want or need to know, I think.

I had had the 12v load(s) coming off the batteries.  Then I read in the manual that the Rover load connection terminal is good for 20a so I did some rewiring and can now read load Ah as well as amp draw in real time.  I did however install a second 12v marine socket off the batteries for whatever additional charging/playing is necessary like phones or a DVD player.  The main draw is the Max Burton fridge so that comes off the controller for more accurate usage attention.

I still have more of the learning curve ahead of me but I believe this system is properly set up for the vehicle and the camping needs. The fridge and a coupla lights is all this vehicle needs.

 

[jonsun]

I've been looking at the renogy clone MPPT's....even if you dont want or cant use the MPPT they come with remotes and user programming for under $150. Then you don't need the battery monitor.

https://www.amazon.com/ENZPOWER-Con...=1501521935&sr=8-14&keywords=mppt+with+remote

 

[John61CT]

Even if you think an MPPT like Renogy labels is as good as the likes of Victron, how would its features remove the need for a good battery monitor?

 

[jaevans]

Go to Amazon.com and search for "DC clamp amp" and you will find several.  They cost lots more than AC clamp on amp meters, are not as accurate, have trouble with zero, but they exist.  I got one for $35.

Thanks - I looked them up before your reply and I stand corrected, but didn't really believe they were all that accurate if they did exist.  I've asked the moderator to delete my original reply so don't be surprised if it vanishes.

John

 

[regis101]

Whelp.  The time has come.  I'm heading out into the big bad werld for five whole dayz.  Tomorrow thru Friday .  
Exciting. huh?

I'll be dry camping at the local campground.  Weather is to be in the 90's during the day and 60's at night.

I went through a bit of a brain drain due to some , prolly, bad youtube advice about mismatched panels and still having them work.  So I'm still educating myself.

I've studied the whole series, parallel, series-parallel thing over and over.  If I crunched some numbers correctly, it seems to be that with an even number of similar panels and using series-parallel with each set in series as an odd number, the math works out to get better wattage.  I bookmarked it . I'm using four similar panels, two sets of two, and each of the three wiring configurations giving the same end result. I chose the series-parallel with regards to using an MPPT and wiring distance.

Anyway, in my case, I was wanting to have some panels fit into the luggage area on the VW Weekender pop top to keep batteries fresh. Read that as smaller wattage, amperage, yet still in the ~twenty v range.
I was able to find two thirty watters that fit nicely.  I also have a bulkhead outlet that's wired to the controller so as to add more portable panels.  

But then I find out that the two one hundred watters that I wanted to use as the portable units wouldn't jive effectively with the smaller thirty watters.  Soooooo, I picked up two more similar thirty watters for a total of one hundred twenty watts of potential.  Which is pretty much all I need with one hundred Ah of battery. But can't have enuff solar, eh?

I found a rule of thumb regarding the PWM vs MPPT and it seems that until the two hundred watt threshold is broken, PWM is just fine.  I'm liking the Renogy Rove MPPT 20a since it has an LCD readout that helps me see whats going on, but not all.

Well, in my case, I have a twenty amp renogy MPPT.  What?  That seems dinky. Who uses MPPT on small array's. I am I am.

What and where I now am at at this point is I have two thirty watters vehicle mounted and in series.  I then have two more thirty watters that are in series as portable and both sets tie together with a three wire splice.  Thus, series-parallel.
I'm producing up to forty volts and three and a half amps and I'm wanting to see the MPPT do its magic.  

I am also bringing the two one hundred watters in case the twelve volt load(s) overwhelm the four, thirty watters.  I will then divorce the said system and push some amps via the two, one hundred watters, to get the battery back up.

This trip is only going to involve solar.  The compressor fridge load is small but will be a first for me to view the nighttime battery depletion with said load running and seeing the time it takes to build back up.

This should be a fun learning experience.  I am prepared to wire and rewire as necessary to reach the self sufficient goal, albeit , a small one.

Hey, even the best had to start at the beginning.  

Thanks for reading.  This was more of a cyber unload for me than seeking advice but will accept any replies.  I'll take some pics.

 

[frater secessus]

I'll be dry camping at the local campground.  Weather is to be in the 90's during the day and 60's at night.

Sounds like a great way to test stuff out.  Far enough from the familiar to allow for thoughtful evaluation, and close enough to home to be able to dash back if needed.

Well, in my case, I have a twenty amp renogy MPPT.  What?  That seems dinky. Who uses MPPT on small array's. I am I am.

I own a 5A Genasun MPPT controller that was paired with a 60W panel about 10 years ago.  That panel was $250 (!) if I remember correctly.  The controller was made for small sailboats that needed max power from very limited real estate.  It had a hand-lettered serial number.

 

[John61CT]

They make MPPT controllers on an IC now, designed to incorporate right into a panel, can do one chip per string.

 

[regis101]

Whelp, my trip was a success on multiple levels. Peace.  Quiet.  Ample shade.  Plenty of sun.  Good food.  Good drink.

 I first used the two 30 watt series that are now hard mounted yet hinged in the luggage rack and had them paralleled with two 30 watt series as portable.  Chased the sun with the remotes.  Had good results for what it was, 120 watts. Series-parallel, 3.4 nom amps, saw 4.6 from the controller at times.  
 Gotta love the higher voltages from panels in series and what an MPPT can do.
 Used the Max Burton as load and although the vehicle mounted panels lagged at times due to shade, natural and man made for testing, having the two remote panels helped carry things along nicely.  
 Then I broke out the big guns, the two 100 watt panels, in series.  I divorced the wiring for the luggage rack and put away the remote 30's.  I set the 100's on the table and let 'er rip.  I saw improvements across the board vs the four 30 watt panels.  Albeit having more wattage was a bonus.
Charging was easier, The fridge seemed to like knowing it had excess power.  For some strange reason, it drew .5 amp less during its run cycle.  I backed up the LCD readout on the Rover controller with a clamp on amp meter on the fridge feed wire.  
  I took eight pages of notes between what the Rover controller was reading and how the Fridge was running/cycling.
I'll have to post that info in the max Burton thread.  But it was positive.  
  I was basically babysitting the solar set up and load draw for three and a half days.  I wrote down what time the panels started and stopped producing, fridge run cycle times and when, I learned overcast skies are not the same as shaded panels, amperages at various time(s) vs panel voltage(s) during battery charging of the three stages, (AGM's), including load draws, etc.

What I'm a gonna do is put a selector switch into the controller feed wiring from the panels.  One position will allow the two 30 watt luggage rack panels to keep a daily charge on the batteries as well as being able to handle small daily loads if we're out for the day or something.
The second position will be strictly for the remote / portable , one or two, 100 watt panel(s) for increased capacity during longer off-grid stays wherever.

I took ohm readings of the 50' cabling, 10 awg,  for the portables and it was at .1 ohm.  In contrast, I took a reading of 35' of the 10 awg marine wire I have on hand as extra and it was .1 ohm so all is well there.

These posted results were under near perfect laboratory conditions.  I await the time when I can do this data retrieval again in mid winter.  Mild where I'm at but it will be a direct contrast to the middle of summer.  Fun stuff.

Thanks for reading

 

[jimindenver]

Regis, it will pass. I use to drink my coffee watching the output climb as the sun came up. I kept note as to times, temps, conditions and output to the point I knew how many amps we could pull at any given time. If that wasn't bad enough I got a controller that would log every detail and put it into a graph. Talk about geeking out! That did let me see what happens with miss matched panels where the lower voltage array affects the more powerful like a small hose restricts a bigger one. It also caused the controller to constantly look for the sweet spot in the arrays/panels never settling on one voltage.

 

[regis101]

Yep. Yep. Yep. It's just my hang up. I'll calm down after the buzz wears off.

 

[frater secessus]

Well, it's an interesting and helpful hangup for onlookers.

 

[regis101]

Ok.  I'm considering this wiring job finished.  Today I added a household 3-way switch between the PV terminals of the controller and the panels.  When the switch is toward the inside, it connects the two 30 watt panels in the luggage compartment.  When the switch is toward the outside, it connects the bulkhead plug on the drivers side so as to have remote panel(s).  I then installed a 12v piggy outlet into the b-pillar for the fridge and also installed an outside 12v ciggy outlet near the same b-pillar , same circuit, so the fridge can be outside.  As a bonus, since everything is wired with 10awg, I can up the fuse size for the fridge outlet(s) and have increased loads.  There is also a 12v ciggy outlet, different circuit, installed at the bench/bed pedestal for interior 12v loads, i.e., phone or pooter charging, maybe 12v led lighting.

This was fun.  This was my first dabble.  This was fun.  

 

[regis101]

Quick update.  I had a bit of trouble with the male ciggy plug from the fridge after all so I'm changing the the two female ciggy sockets to a trolling motor style two prong twist lock along with changing the fridge plug to a male twist lock as well.  I'm actually gonna buy a new cord and put the twist lock plug on that vs cutting up the factory set up.  easy peasy.

Then, lately, I've been reading lots of threads and posts from others about SoC and potential issues peeps are having with one or more of their components or not, including human error.  And that got me thinking about this system.

Last night after the sun went down and the controller stopped showing incoming power, I turned off the panels and pulled the controller fuse to the batteries to eliminate all load draw.  Just now, after 20 hrs of rest, the two 55 Ah AGM 12v batteries in parallel showed 13.23 volts.  

I'm wanting to think all is well with this system.  I'm writing this to maybe get a head nod, or not, from those schmarter than I to let me know all seems to be within spec.  This is not a back patter train of thought at all. Maybe I lucked out. Maybe doing the homework paid off.

Thanks for reading

 

[John61CT]

No way to really tell bank State of Health without proper load testing.

Yes that voltage is great, if anything it's high.

But that doesn't tell you SoH.

You need an ammeter as well as volts to verify individual charge sources settings are optimized.

 

[regis101]

As of this writing, there are a 102 pages in this forum and they all are asking about the same question(s).  I try to read as much as I can.  All is well.

This post deals with the working of the Renogy Rover 20a controller vs amount of available daylight.  Not that its brand specific but this is the one I have.

I was at the local CG this past weekend.  Now that its October, the sun is low in the sky and for less hours vs mid summer.
The batteries had a full charge when I left the house on Friday.  Load was low to moderate.  
On Saturday morning, I pulled out one of the 100w panels and chased the sun for a few hours due to being parked in the shade and just because.  The controller was in MPPT mode (first stage) for a super long time.  It never hit the voltage to take the controller into Boost mode that lasts two hrs by default setting then should lower into float  (third stage).  
Scrolling through the LCD readout, however, it showed the battery as being 100%.  
I then hooked up a second 100w panel in series and within two minutes , the controller went into Boost mode for two hours and then down to float.

Now, I realize, that being a newb to this solar thing, its gonna take (me) a coupla seasons to get 'er dahn.

Coupla questions.  
One, is it ok that the controller does not go through all three stages in succession every time?
Two, while in first stage, MPPT, it is charging the battery... So is it OK to just stay there as long as I'm putting more into it than taking out?

I may be able to self answer these ? but I panicked and hooked up a second panel in series to increase the voltage to the controller so that the three stages would apply as I know them to be.

Or.. should I be thinking that at any time of the given year, I'm a gonna want to just have the higher voltage of panels in series and call it good?  Might be thinking too hard on this one.

 

[John61CT]

> controller was in MPPT mode (first stage) for a super long time.

The standard term is Bulk or CC stage, voltage starts low, depending on the batt SoC, SC is striving to hit the V setpoint (usually Absorb), batt is accepting max amps.

> Boost mode

Usually called Absorb or CV stage, batt has allowed V to reach the setpoint, SC is now capping voltage, batt is reducing amps accepted

Using standard terms helps all the non-brand-specific behaviour.

> Scrolling through the LCD readout, however, it showed the battery as being 100%.

It is wise to assume the charge source knows its own voltage, but not what is happening at the battery. Verify with known good tools actual volts and amps at the battery.

> One, is it ok that the controller does not go through all three stages in succession every time?

> Two, while in first stage, MPPT, it is charging the battery... So is it OK to just stay there as long as I'm putting more into it than taking out?

Yes, Float should only happen after the bank is 100% Full, which you only know by watching amps at the battery falling to say .005C, .5A per 100AH bank size.

While higher current is flowing, the SC should hold Absorb. If day after day, that means you aren't catching up with usage, or something is wrong.

> Or.. should I be thinking that at any time of the given year, I'm a gonna want to just have the higher voltage of panels in series and call it good?  Might be thinking too hard on this one.

Higher volts is good for MPPT, more watts the better in the struggle to get to Full every day.

Stay within SC max specs of course.

Reduce consumption, or do testing with no loads when possible.

 

[regis101]

I’ll have to learn the standard terms, yes. The wording I used is what the LCD shows. I’ll back that up soon with what the Renogy manual reads.
I concur that industry standard wordage would help