Rethinking my 120w portable solar power panel.
After doing some more testing of voltage on my Wal Not so Smart Group 24 DC battery and my Solar Blvd 120W portable solar panel kit for my 21 foot travel trailer, as well as doing a lot more reading after getting my feet wet, I've come to a different conclusion as to getting far better results.
First off, the PWM module provided with the portable solar panel, while good, is not adjustable for voltage output. Due to DC line voltage losses, 14.4V at the charge controller output is not 14.4 volts at the other end of the 5 meter run of line that they give you in the kit, more like around 14.15. It's programmed and set up more as a power source, not a Golf Cart Battery charge controller, which is really what I need from a solar panel charge controller.
Secondly, since I will at a later time be going with a Trojan battery (s) of sorts that really requires about 14.8 to 15.0V to really get the battery charged to a true 100% recharge, not 90%, this will require a couple of changes.
Most importantly will be that the charge controller needs to be located really close to the location of the battery, but not close enough to be exposed to the corrosive out gassing fumes it generates while charging. I learned this from VW when they mounted their fuse boxes on top of the battery vents, where corrosive damage was done to the fuse blocks and wiring on my MK 4 VW jetta TDI diesel. Really, really dumb move, VW.
I will use 8 gauge strand wire, probably less than a 3 foot run, to handle the first 7.5 amps, as well as allowing for a potential additional panel, from a 20 amp adjustable PWM Charge Controller.
Secondly, I will wire no more than 15 feet from the panel to the PWM charge controller box, the panel needing the ability to track or follow the sun with 2 or 3 adjustments during the day to make the most from 9AM to 3 or 4PM daily. The voltage loss from panel to Charge controller from wire gauge is not as critical as that from charge controller to battery, so keeping the last run of wire thick and short from controller to battery is the critical consideration in this set up.. keep that loss to under 1%, no matter how much the short thick strands of copper wire cost for heavy gauge wire. Over engineer in that one area.
Thirdly and most importantly will be the ability to program and adjust the PWM Charge controller to 14.8 to 15.0V charge input at the battery, not at the charge controller, because that's what really matters when you want to top off charge a Trojan to a true 100% with solar panels on a regular basis. I realize there may be cloudy days that get the battery not completely topped off, however, I'd like enough panel power such that a 50% discharge of 150 Ah to 225 Ah is pretty much recoverable to a full charge in 2 consecutive days of sunshine. I think my daily Amp hour usage will run from 30 to 45 Amp Hours, my parasitic daily losses calc out to about 17-20 Amp hours with refrig and CO sensors. All my lights have been changed out to 48 SMD 3624 3000k flat panel LED's that draw about 5 watts each or about .42 Ah. TV draws about 2.7 Amps, when I watch it and Chromebook about 3 amp when on and charging, and it will charge in about 2 hours,less when turned off.
I believe if I address these three critical areas with a portable solar panel kit, override a standard 14.4V max charge set up with + .6V to 15.0. V at the battery terminals at peak output time of day, temperature corrected, should keep my Trojan batteries living long healthy lives.
I do plan to wipe off the solar panels when dusty or dirty or wet, to keep electrical generation in tip top shape, so as to allow my generator to save as much gas and noise as possible from my fellow campers and boondockers. Sorry if I sound so "green" and anything but Republican, I want to try to be as non intrusive with the wildlife as possible while still having some mobile comforts of home while fly fishing.
Keeping it portable, and using the KISS system was a good start, but reading here, and rereading and reading, and asking questions and PMing has helped me refine what works most cost effectively and best for me. I now probably have way more generators than I need, sitting around.
To everyone that took the time to post up a response, post an important link or send me a PM, I am forever grateful. I am a slow learner, this time it didn't cost me too much.
Probably one of the most valuable links I've read, written from a non biased, non agenda POV that confirmed a lot of the loose ends I've put together with my readings here. Don't run your solar panel and your generator at the same time, keep their charging isolated.
HandyBob and solar panel design basics.
First off, the PWM module provided with the portable solar panel, while good, is not adjustable for voltage output. Due to DC line voltage losses, 14.4V at the charge controller output is not 14.4 volts at the other end of the 5 meter run of line that they give you in the kit, more like around 14.15. It's programmed and set up more as a power source, not a Golf Cart Battery charge controller, which is really what I need from a solar panel charge controller.
Secondly, since I will at a later time be going with a Trojan battery (s) of sorts that really requires about 14.8 to 15.0V to really get the battery charged to a true 100% recharge, not 90%, this will require a couple of changes.
Most importantly will be that the charge controller needs to be located really close to the location of the battery, but not close enough to be exposed to the corrosive out gassing fumes it generates while charging. I learned this from VW when they mounted their fuse boxes on top of the battery vents, where corrosive damage was done to the fuse blocks and wiring on my MK 4 VW jetta TDI diesel. Really, really dumb move, VW.
I will use 8 gauge strand wire, probably less than a 3 foot run, to handle the first 7.5 amps, as well as allowing for a potential additional panel, from a 20 amp adjustable PWM Charge Controller.
Secondly, I will wire no more than 15 feet from the panel to the PWM charge controller box, the panel needing the ability to track or follow the sun with 2 or 3 adjustments during the day to make the most from 9AM to 3 or 4PM daily. The voltage loss from panel to Charge controller from wire gauge is not as critical as that from charge controller to battery, so keeping the last run of wire thick and short from controller to battery is the critical consideration in this set up.. keep that loss to under 1%, no matter how much the short thick strands of copper wire cost for heavy gauge wire. Over engineer in that one area.
Thirdly and most importantly will be the ability to program and adjust the PWM Charge controller to 14.8 to 15.0V charge input at the battery, not at the charge controller, because that's what really matters when you want to top off charge a Trojan to a true 100% with solar panels on a regular basis. I realize there may be cloudy days that get the battery not completely topped off, however, I'd like enough panel power such that a 50% discharge of 150 Ah to 225 Ah is pretty much recoverable to a full charge in 2 consecutive days of sunshine. I think my daily Amp hour usage will run from 30 to 45 Amp Hours, my parasitic daily losses calc out to about 17-20 Amp hours with refrig and CO sensors. All my lights have been changed out to 48 SMD 3624 3000k flat panel LED's that draw about 5 watts each or about .42 Ah. TV draws about 2.7 Amps, when I watch it and Chromebook about 3 amp when on and charging, and it will charge in about 2 hours,less when turned off.
I believe if I address these three critical areas with a portable solar panel kit, override a standard 14.4V max charge set up with + .6V to 15.0. V at the battery terminals at peak output time of day, temperature corrected, should keep my Trojan batteries living long healthy lives.
I do plan to wipe off the solar panels when dusty or dirty or wet, to keep electrical generation in tip top shape, so as to allow my generator to save as much gas and noise as possible from my fellow campers and boondockers. Sorry if I sound so "green" and anything but Republican, I want to try to be as non intrusive with the wildlife as possible while still having some mobile comforts of home while fly fishing.
Keeping it portable, and using the KISS system was a good start, but reading here, and rereading and reading, and asking questions and PMing has helped me refine what works most cost effectively and best for me. I now probably have way more generators than I need, sitting around.
To everyone that took the time to post up a response, post an important link or send me a PM, I am forever grateful. I am a slow learner, this time it didn't cost me too much.
Probably one of the most valuable links I've read, written from a non biased, non agenda POV that confirmed a lot of the loose ends I've put together with my readings here. Don't run your solar panel and your generator at the same time, keep their charging isolated.
HandyBob and solar panel design basics.
