Easy solar charge controller question

[mscans]

see loveyourrv.com for info on the Trimetrics "system".  Ray likes the setup and spends a LOT of time boondocking exclusively using solar with the Trimetrics.

[Yarome]

On 1/27/2018 at 5:29 AM, Al F said:

BTW, I would be still be getting the same total number of RPM's from the engine with jack rabbit starts.  I just would not use the vehicle as many years.

Exactly!

And you pretty much just laid out my current system. Calculated @40-70ah/daily I went with a 440ah bank. 540watt high efficiency high voltage array ~80-125ah daily production. With my personal "fudge factor" off a 330,000ah bank that comes up to an 8-11yr bank... which was my "target" range for this particular bank and rig. (daily production and fudge factors are calculated from my own personal yearly data for durations and areas "I" frequent. YMMV)

For me, it is 95% solar sustainable (100%SOC on a minimum 4 day cycle) with many days of excess solar production that can be diverted to charging device batteries, run the washing machine/dryer, ice maker, etc. without having to cut in to my bank's "life". It could very "likely" be 100% solar sustainable, but when the laundry needs to be done... it NEEDs to be done and I'm too lazy to use a bucket n plunger any more... not to mention... I want ice when I want ice. 

Additional plus's are a consistantly lower/slower charge rate off solar (aka. not slamming the gas pedal and brakes) than shore power or genset. From my experience with previous banks... it's not difficult to exceed the published "lifespan" of a bank.

All well and good for me. However.. that's not practical for some. If your daily requirements are in the 200+ah range you looking at an 800ah bank and the solar to back it up. Weight, space, roof real estate all come in to play. Oh.. and cost, but I think it's already well established that "solar folk" are more investing in their lifestyle rather than trying to save a buck.

What is your "target" range? 5 years until you want to upgrade your rig or consider alternative battery tech? If so, it doesn't make much sense to pay out, pack the weight of, or provide sufficient solar support for a 10yr bank. There is also the cost of the "sacrificial" ah's (that ah capacity you'll never actually touch) to consider. 

As you can see... you can go "quite" deep into the rabbit hole, but it all comes down to long term planning and compromises. The ONLY constant in all of the above is your average daily energy requirements. I guess that's why I tend to harp so much on "energy audit, energy audit, energy audit". Plan, build, spend accordingly.

All that said... again, it's not the charge cycles that matter as much as the available AH potential over the life of your bank, IMO.

[Yarome]

On 1/27/2018 at 5:31 AM, Al F said:

My use of the Trimetric monitor is so I can see at a glance, exactly what the status of my battery AH's are, the battery voltage and the momentary number of amps going in or out of the battery.

X2. Even though I have a remote/monitor for my inverter/charger and another for my solar controller...  the trimetric is the one I look at for overall system performance and status at a glance... and where I get take my logs from.

[Sehc]

The Trimetric system, monitor and controller are designed to operate together. The system gets good reviews. I though, have a Victron BMV-700.

 

[Al F]

11 hours ago, mscans said:

see loveyourrv.com for info on the Trimetrics "system".  Ray likes the setup and spends a LOT of time boondocking exclusively using solar with the Trimetrics.

The website and info he supplies is worth reading.  

From a design perspective, one really needs to read and digest Jack Mayer's website. 

Ray's solar setup is one will will probably work fine. 

I would have liked to see more detail info about the reasons for using a PWM rather than using a MPPT solar controller.  Additionally I didn't see any mention that he installed his five 100 watt panels in parallel, or the size of the wire he used from the combiner box on the roof down to the battery bank.  No mention that one of the reasons the MPPT controller would not benefit him, is all is panels are 12V nominal voltage wired in parallel.  That is also the position on the Bogart website.  As long as you use solar panels that supply 12V nominal voltage there is no need for a MPPT controller.  No mention of the advantages of using larger panels which supply 250-350 watts per panel at 35-40 volts and an MPPT controller.  All these considerations go into designing a solar system. 

I kind of understand I am covering a bunch of technical details, a lot of people don't care about.  However just going to an installer and having solar installed, will some or many times results in buying a system that will significantly under preform.  Some times spending 10% to 20% (i.e. $200-$300) extra  on a $2000-$3000 system will provide a much better preforming system.  However you have to know what to ask for and demand the installer provides the upgraded components.

Handy Bob's website has a very good discussion about quality installs.  HandyBob's Blog Solar & Elect

 

[Al F]

5 hours ago, Yarome said:

Exactly!

And you pretty much just laid out my current system. Calculated @40-70ah/daily I went with a 440ah bank. 540watt high efficiency high voltage array ~80-125ah daily production. With my personal "fudge factor" off a 330,000ah bank that comes up to an 8-11yr bank... which was my "target" range for this particular bank and rig. (daily production and fudge factors are calculated from my own personal yearly data for durations and areas "I" frequent. YMMV)

For me, it is 95% solar sustainable (100%SOC on a minimum 4 day cycle) with many days of excess solar production that can be diverted to charging device batteries, run the washing machine/dryer, ice maker, etc. without having to cut in to my bank's "life". It could very "likely" be 100% solar sustainable, but when the laundry needs to be done... it NEEDs to be done and I'm too lazy to use a bucket n plunger any more... not to mention... I want ice when I want ice. 

Additional plus's are a consistantly lower/slower charge rate off solar (aka. not slamming the gas pedal and brakes) than shore power or genset. From my experience with previous banks... it's not difficult to exceed the published "lifespan" of a bank.

All well and good for me. However.. that's not practical for some. If your daily requirements are in the 200+ah range you looking at an 800ah bank and the solar to back it up. Weight, space, roof real estate all come in to play. Oh.. and cost, but I think it's already well established that "solar folk" are more investing in their lifestyle rather than trying to save a buck.

What is your "target" range? 5 years until you want to upgrade your rig or consider alternative battery tech? If so, it doesn't make much sense to pay out, pack the weight of, or provide sufficient solar support for a 10yr bank. There is also the cost of the "sacrificial" ah's (that ah capacity you'll never actually touch) to consider. 

As you can see... you can go "quite" deep into the rabbit hole, but it all comes down to long term planning and compromises. The ONLY constant in all of the above is your average daily energy requirements. I guess that's why I tend to harp so much on "energy audit, energy audit, energy audit". Plan, build, spend accordingly.

All that said... again, it's not the charge cycles that matter as much as the available AH potential over the life of your bank, IMO.

Good points and info.

[Al F]

2 hours ago, Sehc said:

The Trimetric system, monitor and controller are designed to operate together. The system gets good reviews. I though, have a Victron BMV-700.

 

The trade off on the Trimetric system that it is limited to around 400 watts of solar and they must be 12V nominal panels wired in parallel. 

[Yarome]

On 1/30/2018 at 12:37 PM, Al F said:

As long as you use solar panels that supply 12V nominal voltage there is no need for a MPPT controller. 

That's not always true and shouldn't be a blanket determination. Many "12v" panels wired in parallel can still benefit from an MPPT controller to some degree. It depends on the panels. "12v" panels nominal voltage output (Vmpp) is always higher than 12v... which is required to actually push enough current to actually charge a 12v battery. You have to check the actual specs of your panels, but most will have nominal voltages in the 15-19v~ish range.

An MPPT controller may then be able to utilize a portion of any "excess" voltage to convert into amps. In a parallel only system the benefits would be the most limited but would still likely see "some" benefit. In past years where there was such a price hike moving up to an MPPT it, generally, wasn't considered cost effective.

Nowdays... the price gap between PWM's and MPPT's has decreased to the point where the old thought of "MPPT's are never necessary in 12v parallel systems" (more accurately, not cost to benefit effective) is becoming outmoded. Higher Vmpp's are more common and the price gap's continue to decrease.

PWM's still have a place, but if you have 19.8Vmpp panels and want to pull the full potential out of em then MPPT is a very valid choice.

[Al F]

6 hours ago, Yarome said:

That's not always true and shouldn't be a blanket determination. Many "12v" panels wired in parallel can still benefit from an MPPT controller to some degree. It depends on the panels. "12v" panels nominal voltage output (Vmpp) is always higher than 12v... which is required to actually push enough current to actually charge a 12v battery. You have to check the actual specs of your panels, but most will have nominal voltages in the 15-19v~ish range.

An MPPT controller may then be able to utilize a portion of any "excess" voltage to convert into amps. In a parallel only system the benefits would be the most limited but would still likely see "some" benefit. In past years where there was such a price hike moving up to an MPPT it, generally, wasn't considered cost effective.

Nowdays... the price gap between PWM's and MPPT's has decreased to the point where the old thought of "MPPT's are never necessary in 12v parallel systems" (more accurately, not cost to benefit effective) is becoming outmoded. Higher Vmpp's are more common and the price gap's continue to decrease.

PWM's still have a place, but if you have 19.8Vmpp panels and want to pull the full potential out of em then MPPT is a very valid choice.

I probably should have said "MPPT controller not required", rather than "not needed". 

Although the recommendations I have seen is the MPPT controllers provide the best boost when the input voltage from the panels is the mid 30's or higher and really not worth the effort with 15-19 volts from the 12V nominal panels.

[noteven]

I looked at Ray’s article on loveyourrv.com about the Trimetric and Bogart controller. The Trimetric displays the controller data and it’s functions and settings are done through the Trimetric. The controller is a 30 amp PWM type and can be temperature compensating.

So I has questions on matching panels to this controller. To arrive at maximum possible panel output for a “12v” panel in perfect sun do I divide panel watts by volts:

100 Watts / 18 v = 5.5amps

4 or 5 x 100 watt panels would make max array for this controller?

or is my math wrong? 

[Al F]

1 hour ago, noteven said:

I looked at Ray’s article on loveyourrv.com about the Trimetric and Bogart controller. The Trimetric displays the controller data and it’s functions and settings are done through the Trimetric. The controller is a 30 amp PWM type and can be temperature compensating.

So I has questions on matching panels to this controller. To arrive at maximum possible panel output for a “12v” panel in perfect sun do I divide panel watts by volts:

100 Watts / 18 v = 5.5amps

4 or 5 x 100 watt panels would make max array for this controller?

or is my math wrong? 

I can't speak to the Bogart controller.  There should be something on the website about the specs.  Basically if it is 30amp controller it would be 5 panels.  5.5amps times five 18V panels.  That would be 27.5amps max output of the panels.   

Since you will never get 100 watts out of a panel in real life conditions, can you put maybe 6 panels up there?  Maybe.  The only way you would get 100watts out of the panels is to go to the equator on a perfectly clear day on the summer equinox (about June 22) 

Also consider if you use #10 wire from the combiner box to the controller you could loose 10-15% of the voltage depending on the length of wire.  So instead of getting 18V you are only seeing 16.2V to 15.3V.  So fewer watts are getting to the controller. 

If you use larger wire so you only have a 1% loss you are now getting about 17.8 volts to the controller.

The difference in cost between #10 and say #4 wire, kind of depends on the length.  As a guess, 20-60 dollars.  Of course if you are insisting on the #4 and the installer just installs #10 wire, they are going to have to special order the 20-40 foot length (actually 40-80 since it is round trip) of #4 wire.  They probably buy the #10 in 100-200 foot rolls, which is more economical than ordering #4 wire in short lengths.  Then some installers may get irritated because you are doubting what they install on a regular basis.

 

 

[ALLOY]

The  manufacture's output rating is based on a test  (1kw / square meter) number.

Panels may receive both direct and reflected (snow, water, glass) sunlight.

 

 

 

 

[Yarome]

8 hours ago, noteven said:

100 Watts / 18 v = 5.5amps

4 or 5 x 100 watt panels would make max array for this controller?

Correct. If your panels Vmp is 18v. You'll have to check your panels rating tag. 15-18v is pretty common,but some may go as high as 22v in a "12v" panel.

There is often a misconception about controller max amp ratings. Ie., a 30amp controllers max input is 30amps. That's not, "actually" true. Case in point... the 2030 controller is rated for a max input of 45amps so you are more than safe to plan your array for an average production of 30amps. Ie., 8x100w 18Vmp panels. "Absolute" max production would be 44amps, but you'll never actually see that. "Typical" production would be more in the 30-35amp range. Excess current is limited by the controller from passing to your batteries so 8-100w would, safely, be capable of delivering a 30amp charge (a hair more is better than less).

Note that we're talking a PWM controller with a 12v array here.

That being said... because you "can" doesn't necessarily mean that you "should". While the controller will limit excess input from reaching your batteries, that energy has to go somewhere. Enter "heat".... which is an electronic devices kryptonite.

The whole point of this being.... you are more than safe to push your controllers max output ratings (6-100w as Al said) without fear of doing any harm to your controller or battery bank.

[Yarome]

19 hours ago, Al F said:

...really not worth the effort with 15-19 volts from the 12V nominal panels.

Meh.... with a 17-22Vmpp panel though that could equate to 2k+ah's/year. Over 10 years... 20k ah's additional production... for another $0.60-$0.85 a month (or $0.02-$0.03/day if it makes more sense)? I'll buy that. 

[mscans]

On 1/30/2018 at 3:37 PM, Al F said:

The website and info he supplies is worth reading.  

From a design perspective, one really needs to read and digest Jack Mayer's website. 

Ray's solar setup is one will will probably work fine. 

I would have liked to see more detail info about the reasons for using a PWM rather than using a MPPT solar controller.  Additionally I didn't see any mention that he installed his five 100 watt panels in parallel, or the size of the wire he used from the combiner box on the roof down to the battery bank.  No mention that one of the reasons the MPPT controller would not benefit him, is all is panels are 12V nominal voltage wired in parallel.  That is also the position on the Bogart website.  As long as you use solar panels that supply 12V nominal voltage there is no need for a MPPT controller.  No mention of the advantages of using larger panels which supply 250-350 watts per panel at 35-40 volts and an MPPT controller.  All these considerations go into designing a solar system. 

I kind of understand I am covering a bunch of technical details, a lot of people don't care about.  However just going to an installer and having solar installed, will some or many times results in buying a system that will significantly under preform.  Some times spending 10% to 20% (i.e. $200-$300) extra  on a $2000-$3000 system will provide a much better preforming system.  However you have to know what to ask for and demand the installer provides the upgraded components.

Handy Bob's website has a very good discussion about quality installs.  HandyBob's Blog Solar & Elect

 

check ray's site agan.  he posts a LOT of info on the install, wire sizes, accessories etc.  His reason for the PMW system echoes Handybobs as well.  Again, recheck his site, your needed info is there.

[Al F]

2 hours ago, mscans said:

check ray's site agan.  he posts a LOT of info on the install, wire sizes, accessories etc.  His reason for the PMW system echoes Handybobs as well.  Again, recheck his site, your needed info is there.

This is the Ray's website I went to:  http://www.loveyourrv.com/upgrading-our-renogy-rv-solar-system-to-400-watts/

It appears he is using #10 wire for the run from the panels to the controller.  I didn't see lots of detailed info though.

It would be very helpful if you would provide a link to the info you are quoting. 

Please note, I am not criticizing his install.  I don't have enough info to make a judgement.  

[mscans]

Check here. http://www.loveyourrv.com/update-boondocking-remote-solar-panel-mod/ .  Other separate posts for his batteries, cat. fuse install and a video of the major install that he had help with are also on the site, just have to search, he has a lot of info listed.  His background is an electronic repair guy so he is knowledgeabe in things using electrons for fuel.

I make a point of checking his site weekly, I like his "style".

Good luck in your travels.

 

[Al F]

12 hours ago, mscans said:

Check here. http://www.loveyourrv.com/update-boondocking-remote-solar-panel-mod/ .  Other separate posts for his batteries, cat. fuse install and a video of the major install that he had help with are also on the site, just have to search, he has a lot of info listed.  His background is an electronic repair guy so he is knowledgeabe in things using electrons for fuel.

I make a point of checking his site weekly, I like his "style".

Good luck in your travels.

 

I guess the info is in the video.

[mscans]

The bogart system, monitor and controller (2030 series monitor and solar charger) are designed to work together and does so very well.  the only drawback is that it has a maximum current of 30 Amps., good for a small to medium system.  Bogart keeps up to date with battery manufacturers information and the system is programmed with the manufacturers charging specifications so the system has the ability to self program once you have told it the manufacturer and the actual size of the battery bank.  use it with the temperature monitor and you have almost a perfect (small-medium) system.  Without sounding like an add for them http://www.bogartengineering.com/ and knowing some people's thoughts regarding HandyBob, he was one of the Betta testers for the system and also has good words for the system.