I am upgrading current 3960w of PV with a additional 4200W of PV .We just purchased an electric car so need to cover its recharging loads each day on our off grid system.
At the moment I have one classic 150 wired the 3960w of PV charging 48v battery. The system is doing fine in a two series configuration with the classic 150. The cable runs are shortish though 10 - 15m MAX depending where you measure from.
I have ordered 21 x 200w panels for the additional system. I wanted to purchase another classic 150 and run them in follow me mode charging the same battery.
My issue is the new 4200w of panels will be around 25 - 30m away from the new charge controller. I was initially going to use 20 panels in total for 4000w and run them in two series of 10 but I purchased the extra panel so I could run 3 series strings of 7 panels for higher voltage.
My question is. Is there a voltage that each classic is the most efficient at. If I was to wire the panels in two stings of 10. I would have roughly 72v or if I did 3 stings of 7 I would have roughly 108v. both are within specs on the midnite calculators but is one better than the other? What i mean by that is dose the classic 150 have a voltage its most efficient at? My only reason for going 105v would be cable size on the relatively long run.
Or should I purchase a classic 250 and wire the panels in 5 series and up the voltage more. Or is it better to stick with two classics of the same line ( as in two 150's) when using follow me feature?
Specs of new panels.
Open Circuit voltage Voc (V) 45.6
Short circuit current Isc (A) 5.89
Maximum power voltage Vpm (V) 36.9
Maximum power current Ipm (A) 5.69
System Voltage (V DC) 1000 VDC
Power temperature coefficient -0.40%/K
Operating temperature (C) -40 - +85C
Storage temperature (C) -40 - +85C
Kurt
If I was to wire the panels in two stings of 10. I would have roughly 72v or if I did 3 stings of 7 I would have roughly 108v.
the closer the PV voltage is to your required bank charge voltage the more efficient the conversion, less heat generated etc
hth
add: bold words for clarity
Quote from: Westbranch on July 30, 2013, 11:44:55 AM
the closer the PV voltage is to your bank voltage the more efficient the conversion, less heat generated etc
hth
I agree with this but not "too close".
I seem to recall you need battery volts X 1.33 to get MPPT charging with the Classic so be sure you are over that on string voltage after cable losses.
I have been wrong a lot lately so "your mileage may vary", etc.
Tom
Tom added a few clarifying words to original post.
Should also add that there should also be a few extra PV volts above the "recommended/required charge voltage" for line losses and equipment losses as well as to cover heat related PV voltage droop so that a charge can actually occur.
You need to look at the VOC of the series strings. Unless you live in the tropics you also need to pay attention to temp coeffficients - since VOC will be higher for temps < 25 C.
Looking at your panels - 3 in series gives a string VOC of 137 which is pushing it for a Classic 150.
2 per string would be better for a 150, 3 per string for a 200, 4 for a 250.
Better efficiency for the reasons outlined by Westbranch above and less concern about exceeding the controller input limit (and going into hyperVOC mode) in cool temperatures.
For a different viewpoint...
I would go with three of these panels in a series string. It's unlikely that they will be at opv very often, if at all and the 150 will be ok with 135v input.
Also the Mpv of 36.9 is actually quite variable as various factors like angle of sun NS and EW, partial cover, atmospheric conditions and panel temp will often mean the actual voltage from the panel is lower so MVP for a series of 3 PVs may be anywhere from 85v to 110v
Wire size is probably not an issue.
Just crunching the numbers....
48v * 1.33 = 64v. 2pv series at MVP = 74v. But if PV drops below 32v per PV then v too low for classic to charge battery. Not sure if 48v bank is at higher v, say 54 then does 1.33 rule still apply?
If so then v with 2 panels is too close and you could see Classic not charging battery
So to create more charge in lower PV v ranges series 3 together.
Just IMHO
Dgd
Thanks for the reply's.
I should explain my climate conditionsnd add some more info .
They will be installed in Subtropical QLD Australia. Winter min temps 2 deg C (average min more like 12 deg C over winter) with average day time winter temps of 18 - 25 deg C. Summer temps min 20 deg C max 38 deg C and average day temp 30C. Cold weather isn't a issue in my area.
They will be facing north/ west (So peek output a little after mid day) in my part of the world. fixed at about 15 deg (the roof is at this angle and I am lazy LOL)
My system I have now has two series and performs well and the panels are actually a little lower voltage than the new ones.
I have ordered 21 panels so I have the option to go 3 series and if not I just have one spare panel. (always a good thing)
I always consider average charging voltage of a 48v flooded led acid system to be 51 - 61v range and the bulk of the charge is done around 55V. So I can see how there is always inefficiency's in converting DC-DC so I was thinking two series would be best. Then One person mentioned my 30m cable run and how unless I used some quite thick cable I might see cable losses more than the controller losses I would get at 3 series 108v.
Kurt
As has been mentioned, having three panels in series might push you into hyperVoc. Having two in series will be easier on the classic. Either way you will need some pretty thick cable to have an acceptable line loss.
Here are some numbers:
If you go three in series through 30 meters of #4 cable you will have a voltage drop of 2 volts and a power loss of 80 watts at maximum power (seldom achieved). The power loss in the cable goes as the square of the power produced, so at half power you would be losing 20 watts in the cable.
If you go two in series through 30 meters of #4 cable you will have a voltage drop of 2.9 volts and a power loss of 164 watts at maximum power (seldom achieved). The power loss in the cable goes as the square of the power produced, so at half power you would be losing 41 watts in the cable.
If you go two in series through 30 meters of #2 cable you will have a voltage drop of 1.8 volts and a power loss of 103 watts at maximum power (seldom achieved). The power loss in the cable goes as the square of the power produced, so at half power you would be losing 26 watts in the cable.
If you can afford it, I recommend two in series and #2 cable.
--vtMaps
Good info vtmaps.
The other option would be to run smaller wire from each string to a combiner box closer to the batteries and a short home run of larger wire. Might be cheaper.
For example 30 meters of 10 AWG for each string to a combiner box next to the CC.
This may or may not be less expensive or more difficult to do depending on wire pricing, conduit considerations, etc. For my system I ended up doing it this way with both my arrays.
Quote from: mtdoc on July 30, 2013, 11:55:18 PM
The other option would be to run smaller wire from each string to a combiner box closer to the batteries and a short home run of larger wire. Might be cheaper.
For example 30 meters of 10 AWG for each string to a combiner box next to the CC.
Not sure it's relevant, but thats what I did here - but mostly for reasons of convenience.
I have six arrays. 4 of them are tracking, 2 are simply seasonally-adjusted.
Each of the 6 arrays are wired using 4 sq mm cable. (about 11 AWG), but the arrays range between 20 and35 metres from my battery/controller/inverter area. Each array comes in to a combiner panel inside where each cable has a double-pole DC rated breaker, a schottky diode (to prevent backfeeding to any array) and a 10A DC meter. A tiny PLC measures the bus voltage and individual array currents (I use the meters themselves as the shunts). It's very nice to be able to see each arrays output to know if one isn't tracking, needs cleaning or has some other problem! (And the cheaper and easier to work with wire is nice)
All good info I will go with two series 20 panels total.
The panels that I have now 24x 165w are wired in 2 series 2 parallel into a combiner box that's mounted to the railing just under the panels. So in total there is 6 or the 2s 2p strings. From each of the 6 combiner boxed is a slightly thicker wire that runs down to a breaker box near the charge controller 6 beakers in total then one larger wire for 1m to the classic.
When I say my new panels will be 30m away its not quite true. The layout of the panels will be in two long rows of 10 so roughly 10m long. The closest panels on the left will be 25m and the most distant roughly 35m. I did think several thinner wires could be better.
I could go 5 strings (800w each - 4000w total ) with 4 panels in 2s - 2p for each string. Perhaps that is best like the picture below. And some kind of combiner box for each string mounted on the railing and then run 5 thin wires (only need to handle (10A - 800w each) run them back to the power room into a box with 5 breakers then larger short cable to the new classic.
lots of options I guess.
(http://i1105.photobucket.com/albums/h352/kurtthrun/pvlayout_zpsd22d8af5.jpg)
Kurt
Quote from: offgridQLD on July 31, 2013, 04:41:46 AM
All good info I will go with two series 20 panels total.
Just realized - I left off perhaps the most critical bit.
My arrays are each 6, nominal 12V, 100W panels. Vmp around 17V, gives an array Vmp of just over 100V and a nominal Voc of 126 (although it does go significantly higher I've noticed)
I chose this arrangement because 6 panels @ 100W each are easily managed by one person and have plenty of flexibility in configuration. Also if one gets damaged, it's easier/cheaper to replace one 100W module than larger ones.
Quote from: RossW on July 31, 2013, 05:02:35 AM
Just realized - I left off perhaps the most critical bit.
My arrays are each 6, nominal 12V, 100W panels. Vmp around 17V, gives an array Vmp of just over 100V and a nominal Voc of 126 (although it does go significantly higher I've noticed)
..which would be the equivalent of a string of 3 in series 36v PVs. :). Are you using a Classic 150?
So getting near hypervoc is not an issue?
Quote
I chose this arrangement because 6 panels @ 100W each are easily managed by one person and have plenty of flexibility in configuration. Also if one gets damaged, it's easier/cheaper to replace one 100W module than larger ones.
Hopefully that (damage) is never an issue, interesting though that economy of scale seems to kick in with larger wattage PVs, I see here in NZ that 295 to 320 watt PVs are around 86c/watt but 85 to 110 watt PVs are near $2 per watt.
Dgd
We are seeing similar prices this (NA) side of the pond... I think it might be a $$ drop as GT is seeing subsidies dropping or disappearing all over the world, leading to over supply
well,
Here on this side of the pond (the US), folks who based their long term models on
the whims of the US government really haven't bothered to read their history,
not even the history of solar power.
if it doesn't make sense absent subsidy, then it doesn't make sense.
Quote from: offgridQLD on July 31, 2013, 04:41:46 AM
All good info I will go with two series 20 panels total.
Kurt
Hmmm, ok, since you already use PVs in serial pairs to charge a48v bank an you see no issues then this must be good.
I could never see this working for me, I suppose it would be the equivalent of my 24v bank being charged by a single 36v panel (or lots in parallel)
To keep the classic charging that's 24v plus a third of 24v or 32v input needed or even higher when the bank is up to 27v. With variable weather conditions that PV would not always be near 36v.
So what I'm saying is there is vary little voltage headroom for the mppt to work with.
As for those posting that input voltage should be closer to battery voltage to increase the Classics efficiency (and generate less heat someone said) I would say 'show me the evidence'.
boB posted some time ago when asked about the efficiency of the Classic with different battery V versus different input V that it had not been tested and anyway such measurements would be very variable. I think it was in reference to the efficiency graph that was supplied with the MX 60 and why there was not a similar graph for the Classic.
Heat is not an issue AFAIK since I generally only see my C150 and C250 get warm when near max current output. Certainly negligible heat when in BULK MPPT 70A output at 28v with 75v PV input.
Maybe someone from MN can comment factually on this.
And I still think to get decent charging with enough voltage headroom for mppt to work efficiently that a 3 series string of 36v (nominal 24v) panels is the way to go :)
Dgd
To clarify what I meant by 'closer to the required bank charge voltage' is:
it is more efficient to down convert from 36V (nom.) to 24V than it is to convert 96 or 72 V to 24V.
As DGD has pointed out, when you are using Gt-type panels with a Vmp that appears to be, for example, 12 v, {vs the ones truly classed as 12 or 24 V which yield the proper voltage needed to charge one of those 2 categories of battery} one needs to make sure that in inclement weather that you will get an adequate voltage for charging, particularly the Absorb phase where voltage is held constant and Amperage drops.
I believe it was boB that stated a good value to target when determining how high a PV generated voltage you will use, is to target 80% of the max the CC can handle, so for the Classic 150 it's =~ 120V. This is not an absolute but a safe level that does not stress out your equipment.
Mind you Chris Olsen has posted his experience with maxing out his classics hooked up to his Wind turbine(s). Eventful ! to say the least.
Operating voltage is not a 'use this number' as there are all the site specifics that change location to location, the one you pick is specific to you, and the one that will charge your batteries, properly and safely.
I concur with dgd as to 3 panels appears to be a good fit for a 48V battery. :)
Quote from: offgridQLD on July 30, 2013, 06:20:27 PM
They will be installed in Subtropical QLD Australia. Winter min temps 2 deg C (average min more like 12 deg C over winter) with average day time winter temps of 18 - 25 deg C. Summer temps min 20 deg C max 38 deg C and average day temp 30C. Cold weather isn't a issue in my area.
Looking at your panel data - based on the temp coefficient and VOC - with a string of 3 you'd be at 149.4 Volts at 2 degrees C. So you'd be ok voltage wise with a string of 3 - just barely.
Apples and oranges IMO. A string of 2 and the controller will run cooler and be more efficient but you'll need larger wire for your 30m run or lose some efficiency there and have less headroom in case of partial shading etc.
So bottom line - either 2 or 3 in a string will work - tradeoffs either way.
Quote from: vtmaps on July 30, 2013, 10:31:45 PM
As has been mentioned, having three panels in series might push you into hyperVoc. Having two in series will be easier on the classic. Either way you will need some pretty thick cable to have an acceptable line loss.
I forgot to mention, you might consider aluminum wire for the cable. Thick aluminum is less expensive than thick copper. However, there is some cost in making safe connections from the aluminum to the copper on each end of the cable. --vtMaps
I just looked at controller losses here:
http://midniteforum.com/index.php?topic=1316.msg10518#msg10518
and found that they are actually quite a bit higher than expected for higher pv voltages, at least with the CL150.
Given the size of your arrays, and the distances, working at much higher dc array voltages seems where you are headed though...
I would say that your application sounds to me like as good an example of where ac coupling would work as any. We live in changing times, and ac coupling is gaining ground.
The downside is starting again on all your gear though.
So what are they like under 90V? I played around with my wiring yesterday and had just under 70V feed the classic 150charging my 24v bank
I wont be getting any shading on the pv in my location. When I need to make 60v is during the (absorb stage) usually mid morning and I don't see a situation where I couldn't make 60v from two 36.9v pv's that I listed before. Though I could be wrong.
This is the specs of the 24 panels wired in two series that have now on my roof. they have been working fine in my local conditions on my classic 150.
(http://farm4.staticflickr.com/3702/9427836206_f8286ff032.jpg)
From what I can see they are actually slightly lower voltage than the new PV I want to install.
The new pv has a Power temperature coefficient -0.40%/K so dose this mean for every 10deg C rise in temp over 25C. I will get 4% drop in voltage?
Heat is way more of A issue in my location (subtropical QLD Australia) than cool weather. My thinking is typical summer weather is 30 deg C - 38 deg C. Now how hot would the pv be on the roof 55 deg C or more? that could be a 15% voltage drop. so 62.7V for the new PV.
As for the voltage of 3 series being on the cuff for the classic 150 at 2 deg C. It would never be 2 deg C in the day time in my area. Perhaps a once in 100 year record would be 2C over night .
I have ordered 21 panels pick them up next Tue. If I have to go 3 series I can with 3x7 . If not I have one spare PV (not such a bad thing I guess if one got damaged)
Kurt
Quote from: offgridQLD on August 03, 2013, 02:27:36 AM
I have ordered 21 panels pick them up next Tue. If I have to go 3 series I can with 3x7 . If not I have one spare PV (not such a bad thing I guess if one got damaged)
If you go three in series I predict that your Classic will be running VERY hot.
This is because:
1) the Classic is less efficient at the higher voltage
2) you are operating at its upper power limit and more power = more heat (for any given efficiency)
3) the Classic is less efficient at its highest power (for any given input voltage)
4) you are operating in a relatively high ambient temp
--vtMaps
Boy that is a tough one. The comments made by VTmaps is spot on "But" being in Australia I also worry the 70ish volts VMP may sag enough to be an issue in the heat. That said I would agree with VTmaps and say definately wire 2 in series and try it.
Ryan
Well I am counting on the fact that I haven't had any low voltage issues with my 3960W system that's wired in two series and Last summer was a hot one.
That said perhaps the old Polycrystalline BP panels I have up there now are better in the heat than the new additional Mono ones I am getting
The old BP Polycrystalline Cell specs (that did fine in 2 series over summer hit 38deg C a few days over summer)
Temperature Coefficiency of Isc 0.065 %/ºC
Temperature Coefficiency of Voc -0.36 %/ºC
Temperature Coefficiency of Pmp -0.50 %/ºC
vs new Mono cell specs
Power temperature coefficient -0.40%/K
Open-Circuit Voltage Tempreture Coefficiency -0.31%K
Short-Circuit Voltage Tempreture Coefficiency 0.06%K
The new Mono's are 36.7V x2 = (73.4V) VS 35.2V x2 = (70.4V) for the old Polycrystalline's
Kurt
Quote from: vtmaps link=topic=1311.msg10584#msg10584
If you go three in series I predict that your Classic will be running VERY hot.
This is because:
1) the Classic is less efficient at the higher voltage
2) you are operating at its upper power limit and more power = more heat (for any given efficiency)
3) the Classic is less efficient at its highest power (for any given input voltage)
4) you are operating in a relatively high ambient temp
--vtMaps
1). Midnite have never produced efficiency figures/graphs showing batt volts vs input volts so where is the evidence of this?
2). operating the classic at the upper power limit should have no bearing on whether the PVs are in strings of 2 or 3. All the voltages of a 3 string are well within the operational parameters of a classic 150
3). Eh? Again no evidence for this within its working limits. Where has MN published this info?
4). Ok, but this should not be factor in the decision on 2 or 3 nominal 24v panels in series.
I would say your predictions are unlikely and the advantages of giving the classic some voltage headroom for mppt to work efficiently far outweighs any perceived unproven classic temperature
Issues.
Dgd
Quote from: Halfcrazy on August 03, 2013, 05:38:51 AM
Boy that is a tough one. The comments made by VTmaps is spot on "But" being in Australia I also worry the 70ish volts VMP may sag enough to be an issue in the heat. That said I would agree with VTmaps and say definately wire 2 in series and try it.
Ryan
Spot on eh?
So does this mean that classic 200 and 250 designed to allow much higher input voltages are significantly less efficient than a 150?
Does Midnite recommend keeping PV string voltages just above battery voltage to get maximum efficiency from a classic?
You seem to be recommending two nominal 24volt panels in series to charge a 48volt battery bank
Dgd
Quote from: dgd on August 03, 2013, 07:41:08 AM
Quote from: Halfcrazy on August 03, 2013, 05:38:51 AM
Boy that is a tough one. The comments made by VTmaps is spot on "But" being in Australia I also worry the 70ish volts VMP may sag enough to be an issue in the heat. That said I would agree with VTmaps and say definately wire 2 in series and try it.
Ryan
Spot on eh?
So does this mean that classic 200 and 250 designed to allow much higher input voltages are significantly less efficient than a 150?
Does Midnite recommend keeping PV string voltages just above battery voltage to get maximum efficiency from a classic?
You seem to be recommending two nominal 24volt panels in series to charge a 48volt battery bank
Dgd
Significantly less no not at all but slightly less efficient yes. Think of it this way take a 10 watt light bulb and close it inside an aluminum case. after 2-3 hours the case will get hot. So 0.5% in efficiency on a 3000 watt array would be like sticking a 10 watt light bulb in the case so that would be a fair bit of heat and this is exactly why the 200 and 250 drop of in current ratings. So as you can see a 10 watt hit in efficiency with a classic running at max load of 3-4KW to run a smaller wire for a long distance would be trivial but it is also heat so that is why we had to make the 200 and 250 handle less Amperage. So for those systems with long wire runs a slight hit in efficiency is well worth the major savings in copper. I worked on a system design the other day that was like 750 ft of wire and needed 4 Classics. We where talking thousands of dollars difference in Copper when looking at using Classic150's or 200's or 250's so it really simply comes down to what is correct for that particular install. I have used statements like "If the array is 0-100ft away use a 150 more than that use a 200 or 250 depending on wire size etc"
In a perfect world I would go 3 panels in series on a 48 volt battery when using the standard 37VOC panels but in this case the panels are 44VOC so that puts it very close to 150 and if it gets much below 77F there the Classic would be in hyper VOC. What I tell people is to design the PV array based on several factors Distance from the controller, battery voltage and ambient conditions being a few of them. I always start my designs around a Classic 150 when possible do to it being more powerful, less expensive and slightly more efficient (Efficient do to the lower VOC not hardware) but at the end of the day DGD is correct it is a good idea to have some headroom to allow the Classic (or any MPPT controller for that matter) to work.
In my own 48 volt system I have 3kw with a VOC of 89volts into a Classic 150 and a second 3kw running a VOC of 185 volts into a Classic 200 and the 200 definitely runs hotter. I will try to look mid day when they are both cranking and get temperatures. I am not concerned about the heat though, one thing about the Classic is the case is the heatsink so unlike the Outback where we buried the FETs inside and shielded the heatsink inside the metal box the Classic intentionally drives the heat to the casting. So the user will Feel like it is running hotter when in reality the electronics are probably cooler?
Again to back up what I would ideally say for this particular system would be 3 in series but I would suggest a Classic 200 just to eliminate unwanted time in Hyper VOC. My concern on 3 in series is not heat related at all but HyperVOC related. I have no real hard fast rules on VOC vs battery voltage but I can say that to low a VOC is common and then you suffer losses do to the controller not being able to MPPT the array. This is especially pronounced when someone takes a C40 of the wall and drops an MPPT controller in its place. Typically if the array was designed correctly for the C40 the performance may actually drop with MPPT because of the low voltage
Ryan
Quote from: Westbranch on July 31, 2013, 09:05:29 PM
I believe it was boB that stated a good value to target when determining how high a PV generated voltage you will use, is to target 80% of the max the CC can handle, so for the Classic 150 it's =~ 120V. This is not an absolute but a safe level that does not stress out your equipment.
Mind you Chris Olsen has posted his experience with maxing out his classics hooked up to his Wind turbine(s). Eventful ! to say the least.
Hi Wb,
It is not exactly clear what voltage you are referring to with the 80% you noted.
Certainly, this 80% is not for the string Vmp, into the CC, which would be TOO HIGH, IMHO.
Generally, believe that running three of the new PVs in series would be just a bit too high for a Classic 150.
One of the systems here runs three 35.4 Vmp PVs per string which yields 106-ish V strings. In this moderate climate, the highest recorded Voc on the MX-60 (which we still use on this system) is 141 V.
For this system, loss of efficiency on the MX CC is striking when in Float with light loads. With only about 4 - 5 Amps load on the output of the CC, the Vin is about 122 V, even in Summer afternoons with nominal ambient temps of about 35 degrees C. The MX, even with this light load, runs its internal fan at times, even with the temps inside the power room at about 21 C. This is with an efficient CC, but with a relatively high Vin delivering few watts.
One way to mitigate this situation, obviously, is to place a relatively large load on the inverters, causing the almost Voc condition to be reduced to a value much closer to string Vmp. Here, the noted large load(s) are usually A/Cs. The A/C that has priority is the one in the power room, trying to keep the batts and electronics as cool as possible.
And Kurt, most of the time, the highest Voc is experienced early in the morning, around Sun rise, where the illumination from the sun is very low -- insufficient to heat the PV's cells very much at all, and when the lowest temps are usually experienced. With a great CC, like the Classic, with its HyperVoc circuitry, you might just miss some charging in the early AM with strings of three of these PVs, but likely, this reduction should be small. To me, the most dramatic effect of high string V, is efficiency reduction.
I have no measured data to provide on the observed efficiency reduction, just anecdotal observations, which to me, are fairly striking, and not at all a Linear function -- appears some form of exponential function.
As HC Ryan mentioned, perhaps considering a Classic 200, given your PV wire run could be in order.
Just opinions, from the Center Of Nowhere, Vic
Quote from: dgd on August 03, 2013, 07:32:09 AM
1). Midnite have never produced efficiency figures/graphs showing batt volts vs input volts so where is the evidence of this?
Yeah they have, kind of, check it out:
http://midniteforum.com/index.php?topic=1316.msg10518#msg10518
Why does it only start at 90v? 2 panels in series in warm weather will be a good 20v less than that.
Quote from: zoneblue on August 04, 2013, 08:41:30 PM
Quote from: dgd on August 03, 2013, 07:32:09 AM
1). Midnite have never produced efficiency figures/graphs showing batt volts vs input volts so where is the evidence of this?
Yeah they have, kind of, check it out:
http://midniteforum.com/index.php?topic=1316.msg10518#msg10518
power graphs but nothing about classic efficiency.
Look at the online PDF user manual for the MX60 and see the efficiency graphs there.
Not perfect but a useful guide.
While there also look at the recommended nominal panel voltages vs battery nominal voltage
Dgd
I get the impression those power graphs are a few datapoint snap shots, that they happend to test.
Thanks for the MX60 tip, looks like a great manual. I had previously looked at the FM manual in search of exactly this data, and thats where the 2% figure comes from if memory serves.
Given the manual is a little harder to find; ie:
http://web.archive.org/web/*/http://www.outbackpower.com/pdf/manuals/mx60_pv_mppt.pdf
Heres the graph FYI.
And here are the 24 volt curves for the FM controller (successor to the MX):
--vtMaps
Quote from: zoneblue on August 04, 2013, 08:41:30 PM
Quote from: dgd on August 03, 2013, 07:32:09 AM
1). Midnite have never produced efficiency figures/graphs showing batt volts vs input volts so where is the evidence of this?
Yeah they have, kind of, check it out:
http://midniteforum.com/index.php?topic=1316.msg10518#msg10518
Yeah, not sure why that user keeps hammering on the Midnite guys but I just don't pay attention to that poster anymore.
Just easier on my blood pressure than trying to argue.
Tom
Quote from: TomW on August 05, 2013, 08:53:47 PM
Quote from: zoneblue on August 04, 2013, 08:41:30 PM
Quote from: dgd on August 03, 2013, 07:32:09 AM
1). Midnite have never produced efficiency figures/graphs showing batt volts vs input volts so where is the evidence of this?
Yeah they have, kind of, check it out:
http://midniteforum.com/index.php?topic=1316.msg10518#msg10518
Yeah, not sure why that user keeps hammering on the Midnite guys but I just don't pay attention to that poster anymore.
Just easier on my blood pressure than trying to argue.
Tom
So what does "hammering on the Midnite guys" mean?
Is It not permitted, whatever it means, in the conditions of use for this forum?
I'm not looking for an argument but rather some clarification from you as a global moderator of this forum.
If providing examples of my postings helps explain then please quote them.
Dgd
I do want to point out WE did those efficiency curves for the MX and they are pretty close. Efficiency is a very hard thing to test correctly but those where pretty good. And with the mindset the Classic is pretty much the same efficiency as the MX one could use that graph to estimate with. We probably should spend the time and money and knock out efficiency curves but the logic was it has been tested by 3rd parties and found to be better then most at daily harvest.
Some controllers out there may be a touch more efficient hardware wise but way less efficient at tracking so the end result at the end of the day is less KWH's in the battery bank. That is why we decided to spend a BOAT LOAD of money on 3rd party calibrated testing on 7 remote sites in the real world to compare our charger to all of the major competition.
Ryan
Quote from: dgd on August 06, 2013, 03:10:36 AM
Quote from: TomW on August 05, 2013, 08:53:47 PM
Quote from: zoneblue on August 04, 2013, 08:41:30 PM
Quote from: dgd on August 03, 2013, 07:32:09 AM
1). Midnite have never produced efficiency figures/graphs showing batt volts vs input volts so where is the evidence of this?
Yeah they have, kind of, check it out:
http://midniteforum.com/index.php?topic=1316.msg10518#msg10518
DGD
I think what Tom is referring to is some of the harsher stuff like when you asked Andrew "Is there some sort of mental blockage or just stubbornness about providing a node14 type list for each classic?"
Now you may not have intended that as it sounded but it could be construed as you calling Andrew Mentally challenged? I would say if that where the case the post would not be tolerated but. My preference would be for constructive criticism as it really does lite a fire under the Engineers but quotes like above do the opposite. I do not want to drag this thread way off topic so I wont go to far down the path. But we do like the valuable input you have given and have implemented a pretty high % of your ideas.
Ryan
Ryan
Yeah, not sure why that user keeps hammering on the Midnite guys but I just don't pay attention to that poster anymore.
Just easier on my blood pressure than trying to argue.
Tom
So what does "hammering on the Midnite guys" mean?
Is It not permitted, whatever it means, in the conditions of use for this forum?
I'm not looking for an argument but rather some clarification from you as a global moderator of this forum.
If providing examples of my postings helps explain then please quote them.
Dgd
Quote from: Halfcrazy on August 06, 2013, 06:04:01 AM
Efficiency is a very hard thing to test
Ryan, I think *TESTING* efficiency is actually pretty easy, given the right equipment.
Power out (easily and accurately measured) / Power in (easily and accurately measured)
However as you alluded to later, which controller produced the most watt-hours out of a given array under any given conditions is far harder to quantify, because it's no longer merely "efficiency". It includes such things as matching, ability to track changing conditions and a slew of other variables.
Just being pedantic, I know what you meant, but some others I'm sure won't see past "we need efficiency curves".
Quote from: Halfcrazy on August 06, 2013, 06:04:01 AM
That is why we decided to spend a BOAT LOAD of money on 3rd party calibrated testing on 7 remote sites in the real world to compare our charger to all of the major competition.
Ryan,
Is that data available some place? I've only seen the data from 1 site.
>Ryan, I think *TESTING* efficiency is actually pretty easy, given the right equipment.
>Power out (easily and accurately measured) / Power in (easily and accurately measured)
I agree. All you need is 2 shunts, 4 calibrated multimeters, and a variable DC supply that reaches to 150V and 94 amps ;) Jees, does such a thing exist?
Quote from: Halfcrazy on August 06, 2013, 06:10:31 AM
DGD
I think what Tom is referring to is some of the harsher stuff like when you asked Andrew "Is there some sort of mental blockage or just stubbornness about providing a node14 type list for each classic?"
Now you may not have intended that as it sounded but it could be construed as you calling Andrew Mentally challenged? I would say if that where the case the post would not be tolerated but. My preference would be for constructive criticism as it really does lite a fire under the Engineers but quotes like above do the opposite. I do not want to drag this thread way off topic so I wont go to far down the path. But we do like the valuable input you have given and have implemented a pretty high % of your ideas.
Ryan
Thanks for your reply, pity Tom couldn't man up and explain or justify his rudeness. I suspect his attitude towards me goes back some time ago when he got angry with me for not, in his opinion, reading one of his black box postings correctly.
Still, I could not care less what he thinks.. I'm more interested in the Midnite products and their applications than his opinions of me..
Thanks also for your example of my posting. I mistakenly thought that it was obvious I did that posting out of sheer frustration at seeing a very useful mymidnite text display removed for no good reason and the prgrammer responsible just ignored the requests from several users, you included, to retain the text list in mymidnite
Dgd
DGD,
As an uninvolved outside observer, I feel I need to comment. I see no rudeness in Toms post, however I feel you have some sense of entitlement. You seem to think everyone should do what you want IMMEDIATELY. The Midnite crew is working thier asses off on many products, and are not at your beckon call. I understand some of your frustration with amount of time it takes to do some things, but PLEASE lighten up.
Dustin
Boy some times interpreting one another online with written words on a forum can be hard . When the simple things like expression, tone and the like are missing from the communication. I do appreciate the openness between company and consumer that you get with midnite solar. The personal approach to service means something to me.
Anyhow to get the thread back on track. I hitched the trailer up to my my old internal combustion engine 4cly sedan and let it take its last run (what I call digging its own grave ;D) I towed back a big box with 21 x 200w mono solar panels. Why I say the car was digging its own grave is it was towing the panels that will be dedicated to providing off grid power to charge our new fully electric lithium battery powerd car.
Pic of new Mitsubishi Imiev EV and trailer full of PV ... shall we call it our home service station ;D
(http://farm6.staticflickr.com/5542/9449343914_ca4fa22d4c.jpg)
(http://farm6.staticflickr.com/5325/9452747843_e0d0043583.jpg)
So I have the 21 panels and one extra in case I want to go 3 series. Though I think I will go 2 series. I can even play around with just two panels in series on the ground a temporary experiment on location and get a feel for how they will perform (say voltage on a hot day ) before committing to a layout. Going of the performance of my existing panels that have similar specs to the new ones and are running perfect from a classic 150. I think they will be fine. Just might need to spend some more on heavy wire or break the aray up into say 5 sections with indavidual runs of lighter cable and combiner boxes (I'm leaning towards this option)
Kurt
Quote from: offgridQLD on August 08, 2013, 11:10:37 PM
Just might need to spend some more on heavy wire or break the array up into say 5 sections with individual runs of lighter cable and combiner boxes (I'm leaning towards this option)
I would lean towards having the combiner at the panels with a single heavy cable from combiner to controller. Reason: lightning protection.
I like the idea of having my lightning arrestor at the combiner, near the panels and away from my house. Of course, lightning doesn't care what ideas I like ::)
--vtMaps
QLD;
Must be a great feeling cutting out the middle man on your transportation energy source!
Nicely done.
Thanks for the share and sorry this went off topic there awhile.
I am thinking of going with an electric golf cart to replace the ATV I use for farm chores so I can quit buying gasoline to do them. Of course, that means more solar panels. And the addiction continues... :o
Tom
Quote from: TomW on August 09, 2013, 06:49:49 AM
Of course, that means more solar panels. And the addiction continues... :o
Admitting it is the first step... eleven more to go ;D --vtMaps
Ohoh... next it will be pv's on the GC roof,... and..... ;) ;) 8)
PV Sure is addictive. I remember when we first moved in to the off grid house and I mentioned to my wife 4000w is more then we will ever need :o. Looking back its a bit like saying 56k is all the computer processing power one could ever need ;D
It's just so clean, simple and it works. With brand name PV at under $1 watt it really is good value. You can always find a use for the energy. While the additional 4000w we are adding is there to cover the load of charging the car. When I'm not charging the car it will come in handy taking some of the load off the battery's meeting big loads during the day.
I guess you can never have to much PV. Though you have to stop some where.My thinking is each time we add additional large loads to our system we upgrade the PV.
A dream of ours (one day when we can afford it) We would like to install a swimming pool at our off grid house. Running a pump and filter each day for several hrs a day would see me adding another 4000w or so to cover its loads. It hurts paying up front for the energy in the form of PV but in the grand sum of things an extra 4k on a 40k swimming pool to have its energy needs covered for life is good value.
I managed to trailer the 21 panels from the city house up into the hinterland last night. I was flinching every time we drove over a bump. Trying to avoid every pot hole in the road. I even let the pressure down on the trailer wheels to smooth the ride out. The old gas car sure got a workout towing the 1000lb of PV & trailer up the 12% climb. Happy no broken glass :)
Now I need to gather all the hardware, cable, wracking, combiner boxes, beakers, lightning protection...don't think my existing PV has any so that's new to me . The additional classic 150 needs ordering to. I will have a play with two panels on the grass today end experiment with some numbers.
Ps,
If I could count the number of times people have mentioned I should have pv on the roof of my electric ca so I could drive around all day from the sun . GRRRRRR :o most people really have no clue how much energy it takes to move a car. To travel a 60mph powered directly from the PV I would need around 10,000w of pv on the roof of the car to hold speed. Now that is something I would love to see ;D
Kurt
I am also getting juiced up about the Tesla cars pushing the envelope on battery storage but I have always wanted a hybrid or electric 4x4 high ground clearance vehicle and it seems the market for electric cars is kind of limited this way. This thread is kind of diverging into all kinds of directions, so here I register my major disappointment with Elon Musk of Tesla -- if you are such a pioneer of transportation, why don't you make a decent all-electric 4x4?
Give it time and you will have your wish.
If your looking for a project the small susuki 4wd's make a great platform to convert to EV. Run the motor directly to the tranfer gearbox and have a simple 2 speed selection on the dash H-L and Toss the gearbox.
The trouble with the DIY projects is its cost as much if not more than just buying a (edit) OEM EV and are never as good. So you have to have a real dedication to a particular car for it to be worth the time and $$ converting it.
Kurt
Hi OgO,
This may not be enough of an EV for your needs, and may not be sold down-under yet, but:
http://www.toyota.com/rav4ev/
Range only about 100 Miles, oooopppppsssss, sorry ... range about 160 km, and not inexpensive.
You referred to "EOM" in your post, been processing on that, is that the same as OEM? FWIW, Thanks, Vic
Sorry yes typo ... OEM
I'm not looking for a 4wd ev myself. I just purchased a Mitsubishi I-miev EV. I was just about to start building a diy EV. Then Mitsubishi Australia were clearing all stock of I miev's and not importing any more. At under 1/2 the RRP for a new car . I couldn't even purchase the parts for the same money. Even doing all the fabrication work myself the value didn't add up. I just couldn't justify the DIY build.
I'm very happy with the little I-miev It has its compromises but as a package its great for our needs.Driving around from energy straight from your own PV just makes you smile.
It was Lazslo that was keen for a 4wd EV. Yes the rav4 could be a option though I didn't think they were making them anymore and they were crazy expensive even 2nd hand. Not actually a serious 4wd more of a soft of road thing . But might be enough for most peoples 4wd needs.
Kurt
Quote from: offgridQLD on August 13, 2013, 06:27:04 PM
Sorry yes typo ... OEM
I'm not looking for a 4wd ev myself.It was Lazslo that was keen for a 4wd EV.
Kurt
Indeed, so it was ... just dropped a few bits. Have fun with the added PV and enw EV. Thanks, Vic
Thanks for the links and the info guys. Though I have been wrong before, 4x4 EV or electric truck may just be in the works. I would love to have an all eletcric truck and charge it form PV.