I am looking to upgrade my RV solar setup. Currently I have 4- 85 watt 12 volt panels, a midnite combiner box with 4 DC breakers and a 30 amp CC(not mppt). 4 T-105's. I have a 3000 watt pure sine inverter(overkill but it was cheap) to plug the shore power cord into. I have installed a battery disconnect that I use as a manual transfer switch, thats installed on the positive lead coming from the trailer converter.This prevents the trailer converter from trying to charge the batteries
I would like to add a kid and whiz bang jr as well as another big panel....a 235 watt 24 volt Hanwha. So to reconfigure the 4- 85 watt panels to 24 volts seems easy, but then will I need a step down converter to
drop down to 12 volts, or can the kid do this too?
Thanks in advance,
opticalmike
well.....the kid will take the extra volts and convert them to amps for a 12 volt system, but in my opinion those panels are not really compatible.......you'd be better off ditching the 85 watters and just running 2 of the 235's
I have a rubber roof with mounting brackets for the 4 panels...trying not to make swiss cheese of it. just trying to get more watts without covering the entire roof of the fifth wheel with smaller wattage panels. I wonder what the biggest panel I could add that might be more compatable??
Mike,
The Hanwa panels are 60 cell and your older panels are 36 cell, the voltages are going to be too different to work well togather. If you can find 72 cell panels this might work for your situation. Chech the voltage at maximum power ( VMP ) ratings of each panel, if you are real close it will work well. I'm using 36 cell 55 watt Siemens panels in half of my array and 72 cell Suntech 280 watt in other half. I got the voltage within .5 volt so everything works well togather. I think your smaller panels are 18.7 v@max pover X2 is 37.4 and the Hanwa is 29-30 volts, no match.
Might I suggest that you slightly modify your shore power converter to save a bit of power, just add a toggle switch to turn off the 120 vac to 12 vdc converter , inside at the circuit breakers there is a small black wire about 18 Guage that feeds the transformer in the bottom half , switch that lead to turn off converter part of power panel , and you will save a lot of unnecessary power as your batteries will be charged by solar and the converter is not very efficient, maybe idle ing with no load at 100 watts power. There is a relay in the bottom of converter that runs all the 12 volt systems from this converter when you connect to shore power. If you don't disable this then power will go from batteries to inverter at 12 volts , get converted to 120 volts, then to converter at 120 volts ,converted back down to 12 volts then to trailer loads at 12 volts . Double converting = huge loss of power.
Or maybe easier, don't plug shore power cord into inverter, wire a separate inverter only circuit.
I hope I have explained this well enough. I have a Tioga Motorhome converted to a mobile cabin and have been through this one.
td
Quote from: tecnodave on June 18, 2014, 11:55:30 PM
Or maybe easier, don't plug shore power cord into inverter, wire a separate inverter only circuit.
I hope I have explained this well enough. I have a Tioga Motorhome converted to a mobile cabin and have been through this one.
td
I found the easiest solution to this (31ft Keystone travel trailer/cabin) I added another breaker to the panel to shut off the converter....this way I could still plug the shore power into the inverter to light up all existing plugs.
Chris,
Yes that will work as long as you shut off the power transfer relay and the DC converter as well.
Mine has only 3 oddball breakers (G-E Pushmatic) and I would lose my counter top circuit as well so I hacked it.
td
Quote from: opticalmike on June 18, 2014, 10:20:16 PM
I would like to add a kid and whiz bang jr as well as another big panel....a 235 watt 24 volt Hanwha. So to reconfigure the 4- 85 watt panels to 24 volts seems easy, but then will I need a step down converter to
drop down to 12 volts, or can the kid do this too?
Welcome to the forum,
You can keep your old panels and controllers as they are, and add a kid and new panel. No problem having multiple controllers all charging the same battery.
Technodave's suggestions are smart... when you are inverting, don't let any of your 120 volt power get to the converter.
--vtMaps
Opticalmike,
<quote>
I wonder what the biggest panel I could add that might be more compatable??
I have found Epolly brand panels are 72 cell that work well with legacy 36 cell panels. They have a 26" wide module that is a way easier fit on a motorhome as the standard grid tie panels are wider at 34-36 inches and much harder to fit on coach. These are 190 watt, 72 cell, 26" X 54" or so skinny enough you can place alongside of roof vents etc.
Found at NAWS website, they also carry a Chinese clone with the same specs.
Best $/watt value I've found in a non standard grid tie type of module
td
Thank you very much for the wealth of knowledge!
I would love to add the kid and one of those 26" Epolly panels.
what if......
I were to wire in a plug from my 3KW inverter to a ground fault receptacle behind my tv stereo area. Make up a suicide plug male both ends.
plug goes from my ground fault receptacle to the adjacent trailer receptacle thereby energizing the whole trailer. NEVER plug shore power in again...while suicide plug is hooked up.
I do have a breaker on my panel that says generator. I have no generator. Perhaps I could tie into that...
thanks in advance
opticalmike
Quote from: opticalmike on June 20, 2014, 03:05:11 PM
what if......
I were to wire in a plug from my 3KW inverter to a ground fault receptacle behind my tv stereo area. Make up a suicide plug male both ends.
plug goes from my ground fault receptacle to the adjacent trailer receptacle thereby energizing the whole trailer. NEVER plug shore power in again...while suicide plug is hooked up.
I do have a breaker on my panel that says generator. I have no generator. Perhaps I could tie into that...
thanks in advance
opticalmike
Mike;
It would be best to install a transfer switch where the wiring enters the breaker panel. For years I used common plugs and outlets to switch circuits from grid to inverters. 2 outlets, one for inverter one for grid. A plug on the feed to the circuit. Switch where its plugged in to use the different source. Still funky compared to the transfer switch but better than the suicide plug idea. Pretty fool proof as you cannot be plugged in to both at same time unlike the suicide plug.
Just thinking out loud.
Tom
Mike,
As a practicing electrician........ Do not do a male plug to male plug........DEADLY UNSAFE!
The wiring in most campers, motor homes etc is 14 Guage wire rated at 15 amps at 120 volts , that is 1800 watts. You would not have any protection from over current and the possibility of fire as a result.
Your suggestion to use the generator breaker is excellent. It should have a transfer switch built into the breaker panel as in no condition you would want shore power and generator connected togather.
In any case get some kind of over current protection in there.
If you do connect to gen input of power control panel you will still want to shut off the converter part of the panel. This is not difficult as all of the external circuits are solid wire, only the converter wire is stranded. Put this one on a separate breaker. Most of these panels use Bryant breakers same as a household panel. If you have single space breakers you can subsistute tandem breakers in their place to gain a circuit. See what brand breaker is there and buy same brand twin breaker. Other brands will fit but will void your UL or ETL listings for that panel and may be an issue with insurance if a disaster happens.
td
Mike and TomW,
Motorhome circuit breaker panels are vastly different than home panels,
They are multifunction as follows:
1). AC power distribution panel ...main breaker and branch breakers
2). Sometimes includes transfer switch for shore power/ Generator
3) DC power distribution panel with fuses for DC in from batt and branch circuits
4) AC to DC converter to supply 12 volts to trailer loads when AC is present
5) house lighting battery charger....part of converter but has separate voltage control
6) power transfer relay.....this relay has a 120 volt AC coil but 12 volt contacts.....no AC output connected to battery input.....AC present ...DC output connected to converter box
To do solar properly you need to shut off functions 4 5 & 6......this is simple as the same wire that feeds the converter in the bottom half feeds AC to converter and power transfer relay.
All the external AC circuits are Romex type wire ( white outer jacket over black , white and bare solid wires. There is only one stranded wire in the AC compartment that feeds the AC - DC converter normally 16 or 18 g.a.
If you put power into the AC panel from either direction (shore power plug or back feeding ) you will turn on the converter and power transfer relay same if you add a transfer switch before the converter box.
If not sure about minor wiring changes post exact model converter box, mine is B&W 6300 as are many other motor homes and I will try to walk you through this easy modification.
Due to lack of availability of G-E Pushmatics, I drilled a half inch hole in panel and added a SPST toggle switch to turn off converter portion of power panel.
By the way, I have found that IOTA brand battery floater/charger to be way more efficient for RV use so when I get a damaged B&W converter I generally wire the Iota in place of the original converter portion of power control panel. $$$. Good Iota. 45amp. =$135. or so. Original B$W box 45a. $$850.
Iota is way quieter <edited>and more efficient than original transformer design.
td
Most motor homes in Class C do not have shore power transfer switches, they accomplish this rather easily, the generator output is directly wired to a outlet box in the shore power cord storage area. To use generator, plug shore power cord into generator outlet connector....same connector as shore power cord......manual power transfer plug and socket. walla...No way to plug into shore power and generator at same time.......wire output of inverter to one of these RV connectors and plug in shore power cord to inverter output socket. These are special connector for RV use only and can be a bit tough to find. Home Cheepo used to carry them and OSH does but any RV dealer has them
I stock them and will post correct numbers for connectors soon.
td
Quote from: tecnodave on June 21, 2014, 02:54:23 PM
Iota is way quieter and power factor corrected switch mode so much more efficient.
The Iota battery chargers are NOT power factor corrected. They are rugged and reliable and cheap. They work great with grid power, but have caused a lot of angst for folks who try to use them with small generators. Two problems come up... very high inrush current and low power factor.
read: http://forum.solar-electric.com/showthread.php?10123
--vtMaps
vtMaps,
Thanks for that info, my bad, I thought that they were power factor corrected. I will edit that post as I do not want to give out bad info.
My generators have huge surge capability as I use wound rotor motors in a lot of my work and the Honda's and such do not survive this duty. I'm using Onan's as they have 4 times the copper in the windings as compared to generators of same power that have built in fuel tanks and wheels.
td
vtMaps,
I just went to solar-electric and read that thread, and I do understand the problem. The Honda EU 2000 I is a high frequency 3 phase generator which is rectified to DC then switched to AC by a high frequency inverter.
There are two problems to this approach. High frequency generator does not have a high surge capability, same with high frequency inverter, poor surge capability.
Generally running a switch mode unit from another switch mode unit will be problematic
I have avoided this using low frequency wound rotor generator and hybrid high/low frequency inverter with massive 60 Hz transformers much like the outback and magnum designs.
True the inverter generators are much more efficient at small loads due to the ability to throttle down, but I do not run my generator for battery charging alone. I have a deep well at 520 feet with a 3 wire 2 hp. Pump at 240 volts. Pump start pressure is at 150 p.s.i. Due to the head between water level and top of storage tank. Start surge is enormous, never run from inverters. I have smoked several Honda and other small generators.
My bigger Onan (6.5kw.NH-3 120/240v.) can pump water, weld and run two Iota chargers without a problem. The smaller one (4.0 kW. Onan Emerald 3 120 volt only) easily runs shop and house and all chargers at once. Only need the big one for deep well and big mig box and stick boxes,all else use the smaller one, newer design, more efficient.
My opinion of high frequency stuff...inverters and generators......more efficient but at a price....not for wound rotor duty....not for high surge loads.
My 3200 watt Dynamote inverter will start a 2 h.p. Ingersoll Rand air compressor, belt drive, cast iron old school, no head unloader, not only start and run but will restart at 125 p.s.i......try that with a high freq inverter and you will see curly blue smoke and fire emitting transistors.
td
Quote from: tecnodave on June 21, 2014, 02:54:23 PM
Mike and TomW,
Motorhome circuit breaker panels are vastly different than home panels,
They are multifunction as follows:
1). AC power distribution panel ...main breaker and branch breakers
2). Sometimes includes transfer switch for shore power/ Generator
3) DC power distribution panel with fuses for DC in from batt and branch circuits
4) AC to DC converter to supply 12 volts to trailer loads when AC is present
5) house lighting battery charger....part of converter but has separate voltage control
6) power transfer relay.....this relay has a 120 volt AC coil but 12 volt contacts.....no AC output connected to battery input.....AC present ...DC output connected to converter box
To do solar properly you need to shut off functions 4 5 & 6......this is simple as the same wire that feeds the converter in the bottom half feeds AC to converter and power transfer relay.
All the external AC circuits are Romex type wire ( white outer jacket over black , white and bare solid wires. There is only one stranded wire in the AC compartment that feeds the AC - DC converter normally 16 or 18 g.a.
If you put power into the AC panel from either direction (shore power plug or back feeding ) you will turn on the converter and power transfer relay same if you add a transfer switch before the converter box.
If not sure about minor wiring changes post exact model converter box, mine is B&W 6300 as are many other motor homes and I will try to walk you through this easy modification.
Due to lack of availability of G-E Pushmatics, I drilled a half inch hole in panel and added a SPST toggle switch to turn off converter portion of power panel.
By the way, I have found that IOTA brand battery floater/charger to be way more efficient for RV use so when I get a damaged B&W converter I generally wire the Iota in place of the original converter portion of power control panel. $$$. Good Iota. 45amp. =$135. or so. Original B$W box 45a. $$850.
Iota is way quieter <edited>and more efficient than original transformer design.
td
Dave, I believe the wire that I disconnected in this photo goes to the converter charger from the generator breaker .Also I was wondering what you thought of the grape solar 160 watt panel from a compatibility standpoint with my 85 watt panels?
thanx again
mike
Quote from: tecnodave on June 21, 2014, 02:54:23 PM
Mike and TomW,
Motorhome circuit breaker panels are vastly different than home panels,
They are multifunction as follows:
1). AC power distribution panel ...main breaker and branch breakers
2). Sometimes includes transfer switch for shore power/ Generator
3) DC power distribution panel with fuses for DC in from batt and branch circuits
4) AC to DC converter to supply 12 volts to trailer loads when AC is present
5) house lighting battery charger....part of converter but has separate voltage control
6) power transfer relay.....this relay has a 120 volt AC coil but 12 volt contacts.....no AC output connected to battery input.....AC present ...DC output connected to converter box
To do solar properly you need to shut off functions 4 5 & 6......this is simple as the same wire that feeds the converter in the bottom half feeds AC to converter and power transfer relay.
All the external AC circuits are Romex type wire ( white outer jacket over black , white and bare solid wires. There is only one stranded wire in the AC compartment that feeds the AC - DC converter normally 16 or 18 g.a.
If you put power into the AC panel from either direction (shore power plug or back feeding ) you will turn on the converter and power transfer relay same if you add a transfer switch before the converter box.
If not sure about minor wiring changes post exact model converter box, mine is B&W 6300 as are many other motor homes and I will try to walk you through this easy modification.
Due to lack of availability of G-E Pushmatics, I drilled a half inch hole in panel and added a SPST toggle switch to turn off converter portion of power panel.
By the way, I have found that IOTA brand battery floater/charger to be way more efficient for RV use so when I get a damaged B&W converter I generally wire the Iota in place of the original converter portion of power control panel. $$$. Good Iota. 45amp. =$135. or so. Original B$W box 45a. $$850.
Iota is way quieter <edited>and more efficient than original transformer design.
td
I guess I posted the second pic first
I should unscrew the lead on the breaker itself and marett everything up.
Mike,
It looks like there were two wires on that breaker, the one in foreground with solid copper is one of the house lighting circuits, the other one with tinned stranded wire is the converter power. Put the solid one back on that breaker and Converter wire on a separate breaker.
That way when at home and plugged into shore power converter can be used.
Turn on converter when on shore power and turn off when using inverter.
These breakers are SquareD Homeline. They are the most common breaker in used in the states. It needs only a 15 amp breaker. Homeline 15 and 20 amp breakers are rated to be used as switches.
This panel does not have a built in transfer switch so it will be easiest and safest to add a outlet box wired to the output of the inverter in the shore power cord storage compartment and plug the shore power cord into that into that when using inverter. Use 10 Guage. 3 conductor wire for this as main breaker is 30 amps. You will not need another breaker for inverter.
Most class C motor homes use this simpler method where the class A coaches have transfer switches.
If you were to accidently feed shore power back into most inverters they will likely blow up so the transfer method is important.
That is not true for inverters that are specially designed to back feed the utility grid of course.
td
Mike,
I missed that part about grape solar, I think that they are 60 cell grid tie type, same incompatable voltage. If they are 72 cell type then you will likely have a match. Cells produce about .45 volts each so my method usually gets a close match, I just count cells as far as strings go, 4 of my Siemens 36 cell panels are 144 cell string at 69.6 volts and 2 of my SunTech are 144 cell at 70.4 volts , only .8 volt mismatch less ,than .6% mismatch! you do not have to have it exact! within 2% or so will work fine.
To make best use of your existing panels seek out the 72 cell ones.
td
Quote from: tecnodave on June 23, 2014, 05:34:28 PM
Mike,
I missed that part about grape solar, I think that they are 60 cell grid tie type, same incompatable voltage. If they are 72 cell type then you will likely have a match. Cells produce about .45 volts each so my method usually gets a close match, I just count cells as far as strings go, 4 of my Siemens 36 cell panels are 144 cell string at 69.6 volts and 2 of my SunTech are 144 cell at 70.4 volts , only .8 volt mismatch less ,than .6% mismatch! you do not have to have it exact! within 2% or so will work fine.
To make best use of your existing panels seek out the 72 cell ones.
td
dave the grape solar 160 watt are 36 cell
Mike,
Probably will be a good match. Check the v@pmax voltage for each type of panel, within 1-2% will work well, if the voltage of each is way off neither panel will work at maximum efficiency and the controller will have a hard time finding the maximum power point.
Your attachment did not post and I don't have the specs for all the panels.
I take a peek at Morningstar's String Calculator because they have most panel characterstics listed in it. Temp correction and all, it will not correctly calculate for Classic as the Classic can handle 50% more power than the TriStar and the TriStar does not have hyper VOC. But you can get an idea from it. MidNites string calculator is better for Classic but you need those specifications at hand to use it.
td
18.5 volts
Cell Size 156mm x 156mm (6.14†x 6.14â€)
Module Dimension (L x W x T) 1474mm x 660mm x 40mm (58.0†x 26.0†x 1.57â€)
No. of Cells 4 x 9 = 36
Weight 12.0 kg (26.4 lbs)
Cable Length 900mm (35.4â€) for positive (+) and negative (-)
Type of Connector
MC4
Junction Box IP65 or IP67 Rated
No. of Holes in Frame
8 draining holes, 8 installation holes, 2 grounding holes
It looks like specs on Amazon, missing the key stuff that you really need, the electrical charastics,
Specifically you need :
Pmax : Maximum power
V@pmax or Vmp : Volts at maximum power
Voc : Volts open circuit
Imp : Current at maximum power
Isc : Current at short circuit
The two most important numbers are Vmp. The voltage that the panels work at.
and Imp The current that is produced at Vmp
Best specs are from the makers themselves.
td
open circuit voltage 22.2v
current at max power point 8.65A
Voltage at max power point 18.5V
Close enough, it does not have to be exact, if within 1-2% you will not notice the difference.
It's real nice to just buy a bunch of the same stuff but that is not always practical for $wise or space wise.
td
In my combiner box there is an Equipment grounding terminal block directly below the negative busbar that the breakers are mounted to. Can I attach a copper wire on the open lug of that busbar to the equipment grounding terminal block? Then I could run a wire from the chassis ground of the inverter to that and have a better way of grounding on the inverter?? Is this practical or even necessary? I was trying to provide the best ground for the inverter short of a portable grounding rod that is installed at each campground.
What would the percentage of charge be for a battery bank of Trojan T-105's if one only charges them up to the 14.3 volts the PWM charge controller goes to (cant program higher), instead of the 14.8Volts that is recommended by Trojan? I would like to get the kid controller and am justifying it to my wife as necessary.
thanx again,
opticalmike
Quote from: opticalmike on June 23, 2014, 10:38:43 PM
What would the percentage of charge be for a battery bank of Trojan T-105's if one only charges them up to the 14.3 volts the PWM charge controller goes to (cant program higher), instead of the 14.8Volts that is recommended by Trojan? I would like to get the kid controller and am justifying it to my wife as necessary.
Don't bother trying to justify expenditure on KID.
Just accept the fact that a commensurate value item of jewellery is probably the only acceptable solution.
As for the charge voltage being too low I would advise you to get that jewellery ASAP before the batteries sulfate up.
dgd
Or alternately just do nothing but talk incessantly and enthusiastically about the new KID on the block and memorize all the features and that it is half the price of the Classic... finally she will beg you to JUST GET IT so she can talk about something other than a charge controller from dawn till dusk...
Quote from: Westbranch on June 24, 2014, 12:56:34 AM
Or alternately just do nothing but talk incessantly and enthusiastically about the new KID on the block and memorize all the features and that it is half the price of the Classic... finally she will beg you to JUST GET IT so she can talk about something other than a charge controller from dawn till dusk...
I thought that only worked the other way about when SWMBO wanted something!
Mike, just buy the jewellery :'(
dgd
Mike,
A lot of Solar controllers treat batteries as 1 size fits all, the charge rate for a group 27 auto battery is the same as a real deepcycle such as a GC-2, T-105 , or L-16 I had to run my generator twice as much as necessary to top the batteries because my sunsavers and tracers would not charge big batteries properly. 14.3 is not high enough voltage for large batteries. The kid and Classic pay for them selves by being able to set voltage , time , and current to the values needed to properly charge true deep cycle batts. The kid can be programmed to charge a 21 volt battery if you can come up with one or the new LiFePo4 lithium Ion 13.3 volt. No limits! Maybe about 60 volts max charge voltage.
I have used mine to charge a 18 volt Nickle Metal Halide Makita power tool battery.
Sometimes I need 15.6 to equalize my L-16 set and my Classic has already paid for itself in less generator run time, less time in maintaince, and more time gone fishin!
It's really nice to go out somewhere with no utilities and enjoy nature without hearing the gen drink dinosaurs. Now at worst after 6 days of fog I need only 2 hours generator run to bulk the batteries and 3 hours of solar to top everything instead of running gen for 5 hours to keep batteries topped up.
Well worth it, but I am totally off grid. I would be 100% solar except my panels don't work worth a dam through pea soup fog.......none of them do......I just need to fire up my Johnny Porta-Nuke....
Battery state of charge is best determined with a hydrometer. The glass float kind is best full charge an your batteries is 1.275 specific gravity (s.g.) I recommend that you get one, measure the cells in all your batteries with hydrometer and keep a notebook of the readings.
All the cells should be within .020-.025 of each other with a reading at full charge of 1.275 after letting the battery sit a while after charging. A voltmeter will give you an idea but the hydrometer is the real test for s.o.c. (state of charge). Auto parts store. About $10-12 . I do not like the plastic float with a pointer and the 4 colored balls is a joke. Real glass float is the way to get accurate readings.
Grounding, the NEC wants you to bond everything togather but with an RV negative is grounded to the chassis so I would suggest 10 Guage green stranded wire bonding wire to all components , charge controller , inverter , and combiner box grounded to the bare wire buss bar on the left side of your converter box . Connect all negatives to frame ground EXCEPT p.v. panel negative goes directly to p.v. Negative input on the kid charge controller. This is because the kid measures it's current in the negative lead. Some other controllers can have the negatives tied togather but not on the kid cc.
The National Electrical a Code (NEC) is pretty specific that there shall be only bond between (AC) neutral and ground and that should be in the main panel. It is standard practice to ground this ground buss bar to the motorhome frame where the DC ground is located. The ground rod provided in campgrounds is an added safety bonus, it insures that your coach will be grounded if there is a fault of lightning strike. Not a bad idea to have a braided copper bond wire with a large clamp to attach to an external ground.
I have pounded two ground rods at my stationary motorhome for added protections but then I am a commercial electrician so I need to practice what I do and preach to others.
td
Dgd & Wb,
I tried a slightly different, when the GF complained about $610 for the Classic I offered her a deal, I would continue using using one size fits all charge controller if she would give up designer clothes and let me buy her one size fits all. Gotta bunch a flak but I have a Classic and a kid with one more soon.
td :)
Quote from: Westbranch on June 24, 2014, 12:56:34 AM
Or alternately just do nothing but talk incessantly and enthusiastically about the new KID on the block and memorize all the features and that it is half the price of the Classic... finally she will beg you to JUST GET IT so she can talk about something other than a charge controller from dawn till dusk...
LOL, this approach worked well for me 8)
So for clarification, I want to add another panel(a compatible version is the grape 160 watt) this brings my camper to 500 watts & 4- T105s
....4 panels 85watts each and the grape 160 watt. I want to re-wire them in series to get the voltage as high as possible.The kid will readjust the voltage from whatever the array above ends up at to 12 volts as long as the current isn't over 30 amps.?
This sounds workable??
mike
Quote from: opticalmike on June 24, 2014, 05:48:05 PM
....4 panels 85watts each and the grape 160 watt. I want to re-wire them in series to get the voltage as high as possible.
This is NOT workable, unless the Imp of the grape is the same as the 85 watt panels. --vtMaps
within 5% or less
Quote from: opticalmike on June 24, 2014, 08:03:20 PM
within 5% or less
Thats impossible, you are saying that a 160watt 12 volt nominal PV with a mpv of 18.5v has a Imp within 5% of an 85watt panel that is also a nominal 12v PV with an mpv between 17 and 18volts ?
Vtmaps was correct first time, these PVs cannot all just be wired up in series,
You seem to be having some basic difficulty with understanding how PVs can be configured in series/parallel and when voltages OR currents have to be the same.
I cannot find any info on the 85 watt panels, you have not posted details so assuming a standard PV type these are likely 36cell types with Vmp 17.4volts and Imp 4.8Amps (or figures close to these)
When you connect the 4 85watters and the 160watt pv all in series the voltages will simply add together 17.4 + 17.4 +17.4 + 17.4 +18.5
The problem arises with the current that can flow through these series connected PV and it will be restricted to that maximum current that can flow through an 85watt PV - ie about 4.8A
This means your nice new 160 watt PV will only make 4.8A and NOT 8.65A.
the 160 watt panel will behave just like a 90 watt panel.
The solution (are you already planning this?) is the four 85 watt pvs in two groups of two in parallel then each group in series with the 160 watt panel.
Total array voltage mpv about 52volts and Imp 8.65Amps.
dgd
Quote from: dgd on June 25, 2014, 03:05:07 AM
The solution (are you already planning this?) is the four 85 watt pvs in two groups of two in parallel then each group in series with the 160 watt panel.
Total array voltage mpv about 52volts and Imp 8.65Amps.
dgd, I suspect your analysis is correct. What do you think the series fuse rating is of the 85 watt panels? You see where this is going...
--vtMaps
Sorry about not listing the panel specs LDK 085P
Vmp 17.3v
Imp 4.93 a
Fuse rating 10 a
IEC: 1000 Vdc / UL: 600Vdc
What about the difference in fuse rating? the grape 160 has a 15 amp max fuse and the LDK 085P has a max 10 amp
2 x 4.93 amps is still under the fuse rating.
Perhaps it may be better to add 2 more 85's than one grape 160 :-\
That way Im all matched up and run them all in series
Mike,
Your original first post in this thread is the way to go. Hanwa panel would be good and rewiring the 85w PVs for 24v. Then the two 24 volt strings of 85s and the hanwa, at 24 volts, can wire into you midnite combiner using 3 breakers.
The answer to your question is that the KID will be perfect for this setup and will do all the voltage down conversion to charge your 12 volt battery bank.
Dgd
Optical mike and the group,
I've posted this before so forgive me for being redundant but this is very basic to solar:
Panels in series must have the same current (Imp) within a few percent to be efficient.
Panels in parallel must have the same voltage (Vmp) within a few percent to be efficient.
Strings should be all panels the same with few exceptions,
Series / parallel strings will have a problem in current sharing,
In Optical's case the 85 watt panels internal bypass diodes will not be able to pass the current of the larger panels and would not divide the current equally leading to the over current in one panel and blowing the bypass diode. Since these are internal some cannot be serviced leading to the loss of the panel. (They can be accessed in panels with junction boxes)
The worst case is when the 160 is in full sun and one or both pairs of 85's are shaded
It has been recommended by one manufacturer (Siemens) that external bypass diodes be wired across any panels that are wired in such a configuration. In Optical's case this would mean adding a diode wired across each pair of 85 watt panels to protect the internal bypass diodes. The reverse flow diodes will not be affected.
These diodes should have a rating of 2 times the panel current and 2 times the total string voltage.
It is not necessary to use Schottky diodes here as we are not concerned with forward voltage drop but Schottky's can be used here.
I try to limit my suggestions to the skill level of the person doing the work, not to my skill level.
Point missed by everyone: This is a 12 volt system.......5 "12 volt " nominal panels in series is about 90 volts @ max power........this puts the kid at a voltage conversion ratio of 7.5 to 1........not in it's "sweet spot"..... Efficiency will be much better at 2 to 3:1 down conversion ratio.
My suggestion. Three strings of two panels each.....two with two 85's in series....and one with two 160's in series.....way more reliable....way more understandable for the newcomer...use a combiner box with approiate breakers for each panel rating........Isc (short circuit current) times 1.25 (NEC safety factor)
This configuration will make shading issues less of a problem, and put the kid at 3:1 conversion ratio, the kid will be more efficient and radiate less heat.
td
would it be better to just go with 2 more 85's and run all 6 panels in series
4.93 x 6 = 29.58 amps
If you put all 6 in series you will be WAY over the sweet spot as Dave put it.
Why? because you have the formula wrong, in series configuration you add the voltage ONLY , in Parallel configuration you add the Amps.
So in your case you will have a nominal Voltage of 6 x 12v = 72V nominal, Voc much higher.
A ratio of 6:1
Quote from: opticalmike on June 25, 2014, 02:54:41 PM
would it be better to just go with 2 more 85's and run all 6 panels in series
4.93 x 6 = 29.58 amps
Putting 6 of those 85 watt panels in series will mean multiplying the VOLTAGE by 6. The current will be 4.93 amps.
Why don't you do what I suggested back in reply #6 in this thread:
QuoteYou can keep your old panels and controllers as they are, and add a kid and new panel. No problem having multiple controllers all charging the same battery.
--vtMaps
Quote from: opticalmike on June 25, 2014, 02:54:41 PM
would it be better to just go with 2 more 85's and run all 6 panels in series
4.93 x 6 = 29.58 amps
If you want to run six of those 85 watt panels, you could put them all in PARALLEL with your current controller (if it can handle the 29.58 amps... you haven't told us what controller you have). Your combiner would need six circuit breakers.
You could also hook up the six 85 watt panels in three parallel strings (with two panels in series per string). In this case you would be combining three strings and your current circuit breakers would be OK. You would need an MPPT controller such as the kid.
--vtMaps
Vt,
I did not recommend that course due to the fact that his existing controller is a Chinese PWM controller. When the kid pulls up the voltage to a true charge for t-105's it will cause the Chinese controller to shut down as it will see a "full battery" . I have this situation with my Chinese Tracer MPPT controllers on same battery with a kid or Classic. I can use my Tracers to assist with bulking, but at adsorb they shut down, leaving all the work to the controllers that can be tailored to the battery type.
This is exactly what I am referring to when I say "1 size fits all" , most Chinese controllers assume a group 27 auto start/deep cycle , there is no provision for a true deep cycle such as T-105's , GC-2's , and L-16's.
My opinion on batteries that have a listed CCA (cold cranking amps) : this is not a "true deep cycle" it is an auto start battery! Not suitable for solar work! It will not stand the repeated cycling found in RE systems and will fail in 90 days or so.
To mimic TomW, that is my story and I'm sticking with it.
td
Optical mike,
I may have misidentified wires in your converter box, going back to the pic's you posted there are two stranded wires in that converter box. On #5 breaker there is a stranded wire going to the bottom portion of the converter, this one is probably the AC to DC converter power, I'm not sure just what the other stranded wire is. Trace it back and see if it exits the back of the box or stays inside. This is on the water heater breaker and might power the transfer relay. There are two open breaker spots and you could easily add one SquareD Homeline HOM1515CP breaker to separate the circuits. The relay when energized makes a clack sound as the relay switches.
td
Quote from: dgd on June 25, 2014, 02:21:45 PM
Mike,
Your original first post in this thread is the way to go. Hanwa panel would be good and rewiring the 85w PVs for 24v. Then the two 24 volt strings of 85s and the hanwa, at 24 volts, can wire into you midnite combiner using 3 breakers.
The answer to your question is that the KID will be perfect for this setup and will do all the voltage down conversion to charge your 12 volt battery bank.
Dgd
would I still be able to use my 12 volt inverter?
mike
Mike,
Think that the rub in dgd's suggestion, is that when you mentioned that the Hanwah PV was 24 V, it is NOT really a 24 V PV. td did mention this fact previously. Almost all PVs in the 230 - 275 W range are 60 cell. Many folks call these PVs 24 Volters, but the Vmp of this PV is just under 30 V. A REAL 24 V PV has a Vmp of about 35.5-ish Vmp. Some will be a bit above 36 Vmp.
As such, strings of two of the real 12 V 85s will not get along well with 30-ish V Vmp PVs, like the Hanwah. FWIW. Vic
Ahh, the danger of making assumptions :(
Having goooggledd the hanwha PVs they all appear to be the 60 cell type so my original suggestion about using one is completely wrong.
Thanks for pointing out this info Vic..
Mike, your suggestion about getting another two 85W pvs looks good.
I would suggest wiring each two in series (ie connect positive from one panel to negative on other then remaining +ve and -ve go to junction box).
So you have three sets of wires going to junction box.
This would mean about 35volts at 14.5A going to KID, ideal for mppt to charge a 12v battery.
Your 12v inverter connects to battery and is not effected by how you configure the PVs into the KID.
dgd
I did manage to get two more 85 watt panels, so if I rewire them into 3 strings of 2 panels what about the 10 amp breakers I have?....do I need to buy the 15 amp breakers?
KID and temp probe and Wbjr and shunt...on their way
These are the panel specs:
Vmp 17.3v
Imp 4.93a
Voc 21.6v
Isc 5.28a
Location Northern Alberta
winters ~ -40C
what would the final voltage be on a cold winter day...we see lots of these!
thanx,
mike
If you use the sizing tool for which ever CC you are going to get it will tell you how high V cold will get for your desired temp...
KID http://www.midnitesolar.com/sizingTool_kid/index.php
Classic http://www.midnitesolar.com/sizingTool/index.php
I believe the kid is rated for 150 volts......so I don't think you have anything to worry about there.....I'm not in northern alberta.....but here in the Kootenays BC I didn't have any problems.
Besides....running them in stings of 2 will only bring you up to 34.6 volts
whats better? I dont use in winter at all. 6 in series, 2 strings of 3, or 6 in parallel? is it better to have more amps or more volts?
Assumption: I believe you are wanting a 12 V b. bank...(?)
So, how efficient or, contrarily, how inefficient do you want the system to be?
The larger the difference of the V going into the CC and the V coming out of the CC determines both!
The recommended difference is to go from one step ie 24 V to the next lower step, ie 12V,
or 48V to 24V... or 96V to 48V.
So in your case you are going from 6 x 17.3 =103.8V too much differential to 12 V
3 x 17.3 =51.9 ... better
2 x 17.3 = 34.6 .... better still
1 x 17.3= 17.3 ... best for 12 v system
Then you have to consider the distance between the array and the b. bank and the line losses.
I believe you are talking about a camper/trailer so losses may be small, now the kicker: the higher the V, the less loss per foot or meter that Voltage has to travel between the panel and the battery... so you trade one efficiency for another loss.
here is a voltage drop calculator you can use
http://www.solar-guppy.com/download/voltage_drop_calculator.zip
My panels are less than 20 ft to the cc and battery bank
Loss on wire is less than 2 % so highest amperage ?
I need 2 more 10 amp breakers
Highest amperage would be 6 x 4.93A = 29.58A from combiner to CC, and depending on what the CC sends to the battery, there could be a (modest) boost in amps depending on battery SoC.
hth
So would the best way to configure these 6 panels is in a parallel config, or 3 strings of 2 in series.
It is up to you, you will save some wire ($) if you go 3 x 2 over 6 parallel. You will lose a bit of energy as heat in the CC though, at 3x2 as you are down converting from '24v' nominal to 12 v.
eg. Due to distances mine will be 48V to 24V so I save on copper and line loss, cool location so a bit more heat.
Thanx for the confirmation...6 panels parallel 17.3v 29.5a and a 12 volt battery bank, Kidd and whiz bang jr.