Basic Panel Question

LucentLucent Registered Users Posts: 8
I have 3 monocrystalline panels (Grape Solar)
36.2 V, 5.25 A,190 Watts

My charge controller is a C-40 Xantrex set at 12 volts.
Max. PV Open Circuit Array Voltage 125 volts
Charging / Load Current (at 25 °C) 40 amps
Max. Peak current 85 amps

My batteries are 6 volt 186 Ah x 10 wired for 12 volts.

Question...Since these panels are 36.2 volts.......can they be used with my charge controller? How can you tell if a panel is a 12 volt panel? It seems that all charge controllers are either 12, 24, or 48 volts....why are the panels listed above are 36.2 volts? Is there such a thing as a 36.2 volt charge controller?

I am very new at this would appreciate any help.

Comments

  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Basic Panel Question
    Lucent wrote: »
    I have 3 monocrystalline panels (Grape Solar)
    36.2 V, 5.25 A,190 Watts

    Welcome to the forum.

    First of all you must understand panel voltage specs. Voc is the open circuit voltage. Vmp is the voltage for maximum power. I think 36.2 is the Vmp for your panels.
    Lucent wrote: »
    Question...Since these panels are 36.2 volts.......can they be used with my charge controller?

    Yes, but it will be very inefficient. You need an MPPT type of controller.
    Lucent wrote: »
    How can you tell if a panel is a 12 volt panel?
    It will have a Vmp of about 17 or 18 volts.
    Lucent wrote: »
    It seems that all charge controllers are either 12, 24, or 48 volts. <snip> Is there such a thing as a 36.2 volt charge controller?

    The 12, 24, or 48 refers to the battery, not the panel. Few controllers can be programed to charge a 36 volt battery.
    Lucent wrote: »
    why are the panels listed above are 36.2 volts?

    Those panels could be used with a PWM type of controller and a 24 volt battery. They can also be used with a 12 volt battery with an MPPT controller.
    Many panels have odd, high voltages because they are use in series to make the very high voltages needed for grid-tie inverters.
    Lucent wrote: »
    My batteries are 6 volt 186 Ah x 10 wired for 12 volts.
    That makes 5 parallel strings. That will be a disaster. You should never put more than 2 strings in parallel.

    Also, That is a 930 ah bank which needs a minimum of 50 amps charging current (more would be better). Your 3 panels will, under optimal conditions only, provide 15 amps to the batteries.

    Panels are cheaper than they've ever been and batteries are more expensive than they've ever been. Off-grid systems are all about taking care of your batteries. You need to figure out what you want to power, then pick an appropriate battery capacity, then buy enough panels and electronics to keep the battery happy.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Basic Panel Question

    Hi Lucent. Welcome to this form. I believe you'll find it the best of it's kind to be found anywhere.
    Yes, you can use you're Xantrex C-40 controller with those panels. Unfortunately, since the C-40 is a PWM type controller, it will not be able to take full advantage of the power available from you're panels. The MAX wattage it can harvest will be the panel's actual supplied amperage X the battery voltage, which will be roughly 3 times 5 amps times 12 volts = 180 watts for the total of the three panels, a far cry from the 3X190=570 watts you might have been expecting.
    However - - - if you change out you're controller for a good MPPT type, such as the Morningstar TS-MPPT-45 or the TS-MPPT-60, all that extra panel voltage can be turned into extra charging amps and you'll end up with the max wattage that can be harvested from the panels. The advantage of MPPT also shows up. even when using "12 volt" panels, when the temperatures are low, which results in higher panel voltages. So-called 12 volt panels will have an open circuit voltage of roughly 20 volts, but you're panels will do awesome with a good MPPT controller. (There are however, some pretty low quality junk MPPT controllers out there, so ask questions here on this form before you decide to purchase)
    On another note - - you mention that you have 10 batteries, 6 volt each, all wired for 12 volts. Expect problems with you're batteries. Why? Because you have 5 strings of batteries wired in parallel, which will result in uneven charge/discharge of the 5 different strings, leading to early failure. Max that can safely gotten away with is 3 strings in parallel, and then only if very carefully wired so each string has EXACTLY, and I mean EXACTLY the same resistance in their wiring to both charging source and discharge loads.
  • LucentLucent Registered Users Posts: 8
    Re: Basic Panel Question

    Thanks so much for your help. I'm such a newbie, but trying hard to understand.

    My panels are indeed VOC=45.4, VMP of 36.2

    OK, so if I buy a Morningstar TS-MPPT-45, I will be able to take full advantage of the panels. I can do that...and maybe in the future upgrade to a 24 volt system, but I would have to buy a 24 volt inverter also.

    You make the point that I have too many strings in my battery bank. If I limit the strings to 3 as you suggest, that will give me 185 Ah x 6 = 1,110 Ah. I could possibly take the remaining 4 batteries and set up a separate system to operate my water pump using the Xantrex C-40. I know that the pump is operating on 120 volts, but do not know what the surge is to start the motor, so I will have to check into that. What panels would work well with the Xantrex C-40 controller since the type I have are too "hot". I don't understand how panels integrate with the controller. I have a basic understanding of MPPT (it automatically adjusts the voltage and amperage for max efficiency), so I guess the PWM controller does not make that adjustment automatically...so it would follow that the panels would have to be more closely matched to the PWM controller. Is that right?

    You state that a 3-string battery bank such as mine needs EXACTLY the same resistance and load, or I will damage the batteries. I understand that to mean the exact same cables (length and guage) at the exact same torque. What type of batteries should I have bought so that I can increase my amp hours? I live in hurricane country and would like to be able to run a freezer, refrigerator, lights, off of solar for two days at a time. I do have a propane generator I can use as back-up, but dislike the noise. I guess what I really need in hurricane weather is a battery charger!

    One final question.... when wiring the panels, I understand that the cables to the controller need to be the same length and guage. Do all the cables from each panel to the Combiner need to be the same length also?

    Again, thank you so much for your help...I do really appreciate it.

    Lucent
  • PhotowhitPhotowhit Solar Expert Posts: 4,994 ✭✭✭✭
    Re: Basic Panel Question
    Lucent wrote: »
    You make the point that I have too many strings in my battery bank. If I limit the strings to 3 as you suggest, that will give me 185 Ah x 6 = 1,110 Ah. (NO, 3stringsx185Ah=555Ah) I could possibly take the remaining 4 batteries and set up a separate system to operate my water pump using the Xantrex C-40. I know that the pump is operating on 120 volts, but do not know what the surge is to start the motor, so I will have to check into that. What panels would work well with the Xantrex C-40 controller ...so it would follow that the panels would have to be more closely matched to the PWM controller. Is that right? (Yep, looking for 12 volt nominal panels, they will have a VMP of 17-18 volts) Try These.

    You state that a 3-string battery bank such as mine needs EXACTLY the same resistance and load, or I will damage the batteries. I understand that to mean the exact same cables (length and guage) (Yep) What type of batteries should I have bought so that I can increase my amp hours? (L-16 are the next step up froma 6V golf cart type battery, then 2V cell batteries, then large traction batteries...) I live in hurricane country and would like to be able to run a freezer, refrigerator, lights, off of solar for two days at a time. I do have a propane generator I can use as back-up, but dislike the noise. I guess what I really need in hurricane weather is a battery charger!(Cheaper)

    One final question.... when wiring the panels, I understand that the cables to the controller need to be the same length and guage. (No) Do all the cables from each panel to the Combiner need to be the same length also?(No)

    Good Luck! Hope this helps.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Basic Panel Question
    Lucent wrote: »
    You make the point that I have too many strings in my battery bank. If I limit the strings to 3 as you suggest, that will give me 185 Ah x 6 = 1,110 Ah.

    No. each 12 volt string is 185 ah. btw, I suggested 2 strings max, but 1 string is optimal.
    What type of batteries should I have bought so that I can increase my amp hours?

    L16 batteries are 375-400 amphours and are relatively cheap. Look at NAWS for larger AH batteries. You could use 2 or 4 volt batteries in series to get high ah in a single string. The best way to get more battery capacity in a single string is to raise your system voltage to 24 or 48 volts. You could use 8 of your batteries to make a 48 volt string.
    I live in hurricane country and would like to be able to run a freezer, refrigerator, lights, off of solar for two days at a time. I do have a propane generator I can use as back-up, but dislike the noise. I guess what I really need in hurricane weather is a battery charger!

    Stop spending money and figure out what you need. Start with the load, pick a battery capacity, and then you can calculate what you need in panels and electronics.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Basic Panel Question

    lucent,
    what is your present inverter that you are using?

    believe it or not a generator with a 3 stage battery charger isn't a bad idea. while running a few loads during the day the charger can be charging up the batteries for night use, but that's only if the generator has the capacity to do both.

    i feel it could've been designed better in the first place like going with a larger battery voltage and larger batteries like the l16. the only way you could go to a higher battery voltage and still use all of the batteries you have is to buy more of those batteries so that it works out evenly. 24v battery banks with 6v batteries are in multiples of 4 and 48v battery banks are in multiples of 8. 2 more batteries would give 3 strings of 4 and this can be done only if the batteries are relatively new (<1 year) and have not been abused. your batteries are being undercharged so there's the abuse. if the wires are differing lengths for each 12v string of batteries then that's further abuse as charging and discharging are unequal.

    now if you run out of propane you will need to rely on solar to charge the batteries. if you opt for a 24v battery bank arrangement the controller you have will work with those pvs. more pvs will need to be added in order to give the proper charge to the battery bank in any case and most likely won't really come into play unless the generator is down or the outage has gone beyond your 2 day expectations. if the genny is to be the main power source in conjunction with a battery charger for the first 2 days the present pvs may be used to keep them maintained during normal times so you won't have need to keep the ac charger on it all of the time.

    btw, you should have a sine wave inverter for the loads you state and they do make inverter/chargers as well and you could even have it with an automatic generator start. you can take this as far as you wish to, but lay it out and plan for it with help and opinions from here. you make the final decisions.
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Basic Panel Question

    Paralleling battery banks can work... Here is a good web page that explains the "proper" way of wiring them up.

    You can put more batteries in parallel--But the maintenance and diagnostic/charging/discharging issues do go up.

    Personally, I recommend one string (with large AH batteries) as ideal. You can do two to three strings--But more than that becomes an issue of diminishing returns (more cells to check for water, more connections to check, you should have a fuse/breaker per string for safety, as batteries age, cells can become open/shorted/imbalanced Specific Gravity, etc.).

    For your first bank, if you already have the batteries--It is sort "why not" use them and get some experience.

    I always recommend to major steps before buying/building your solar power/off grid power system.

    First is conservation--It is almost always cheaper to "invest" in Energy Star Appliances (10+ year old fridge can use 2-5x as much energy as a current model in good condition), and picking "appliances" that do just what you need (for example, a desktop computer may use 200+ watts 24x7 ~ 4.8 kWH per day--Which can be 4x as much mower as a big refrigerator--Instead, get a laptop which powers down when not used--And you may average 20-30 watts 8 hours a day or ~ 0.3 to 0.5 kWH per day).

    Get a Kill-a-Watt type power meter. Plug it into each major load you want to power from solar/off grid power for 1-7 days and log the kWH/Day power usage (as well as the running watts, PF power factor, etc.). This will give you your base load (which may vary between winter and summer) for your power system.

    At this point, then we can help you design a cost effective/reliable power system for your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • LucentLucent Registered Users Posts: 8
    Re: Basic Panel Question

    Wow! There is a lot of information for me to absorb in this thread, and I thank all of you very much.

    To clarify my solar situation, most of the equipment I have was given to me by a friend who has moved out of state. So I am trying to make due with what I have. Now, the batteries are all my doing...I have 4 batteries presently hooked up to the Xantrex C-40 now...the other 6 are brand new and never used. I have two inverters...1) Sunforce Pure Sine Wave 12V 4500 Watt 2) Samlex Pure Sine Wave 12V 1000 Watt. I want to run as much stuff as I can off of the system I am trying to build, but primarily want the system for power outages during hurricanes, etc. The person who wrote in one of the replies on this string was correct in that I should decide what I need and stop spending money which is a very good point, except the only money I have spent was for batteries and a few cables. Oh, I did buy some MC4 connectors and 150 feet of AWG 10 cable for the panels.

    I do have a watt meter and need to gather all the data. It is hard to not just jump in since I have so much stuff tho!

    I had a roofing guy put the 3 panels on the roof...so that's done. I have room for 6 more, if I so choose.

    I just watched a video on the Morningstar TS 45, I think the TS 60 is probably too big for what I need...but I have to get out my watt meter first and get some idea of how much power I want to store in the batteries. Incidentally, with hurricane Isaac, we are not getting much sun, but between clouds I saw that I was drawing 19 amps 198 watts, but the batteries are almost fully charged at 12.7V, so I don't know if the Xantrex charge controller was limiting what was being stored.

    There is a lot to this Solar endeavor I am on...but I want to learn and understand and really appreciate all the knowledge you'all have shared with me.

    I need to consider upgrading to 24 or 48 volts...that way I can make use of the batteries I have. If I set up a separate system for the water pump, then as I need to replace the batteries, I can go with the L16...those are Trojan batteries, I guess...maybe the water pump system at 12 volts and the main system at 24 or 48. The water pump is beside the separate garage and quite distant in electrical terms from the house...I could run the pump and the landscape and flood lights off of that system. Just thinkin........

    Lucent
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Basic Panel Question

    Make sure you keep all of the batteries charged--Flooded cell batteries can easily be damaged if not recharged at least 24 hours (with the appropriate charger) at least once a month (many charger can over charge batteries if left plugged in 24x7--I use a lamp timer set to turn on 1 hour per day to "float" cars that are not driven much--Works very well unless somebody leaves a trunk light on).

    We can make guesses on your power use, and even "design" a system to recharge the batteries you currently have.

    Or base a design on the amount of power you will need.

    It is surprising how much power a "minimal" home will use (I use 3.3 kWH per day or 100 kWH per month as a starting point--one fridge, some lights, maybe a well pump, laptop computer, clothes washer in a reasonably sunny region).

    More than likely, for the loads you listed you will be better of with a 24 volt inverter/battery bank minimum (perhaps even a 48 volt system if you use a lot of power).

    But when you have that much power needs/battery bank to support, you are looking at 1-3 kWH of solar panels (just a guess).

    So, how would you like to proceed--I suggest pick a battery bank or daily power needs, and we can run some numbers--From there, you can decide how to proceed (off grid solar power, if done correctly, is not cheap :cry:; if done incorrectly, it can be very expensive :cry::cry:).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • LucentLucent Registered Users Posts: 8
    Re: Basic Panel Question

    So much information!

    I'm thinking I need to upgrade the house solar system to 24 volts. That way I can use the 10 batteries I have (the 4 batteries that are hooked up are about a month old, and the other 6 have never been used at all...just got them about two weeks ago). Right now, I have a portable fan operating off of the 4 batteries just to draw them down....and I have the panels disconnected. I need to replace one of the MC4 connectors on the main negative lead after the sun goes down.

    I can start collecting wattage data but would like to proceed with a 24 volt system for the house. Any 12 V electronics left over can be utilized in the solar system for the water pump/yard lights. I wanted to convert the water pump to 240 watts, but guess I'll have to stay with 120 to use the equipment I have.

    Incidentally, I moved here ( Northern Fla.) from San Jose about 10 years ago after I retired from Pacific Bell. Sure miss the dry air and the cool nights, but the taxes are better!

    I think that the 45 amp Morningstar should work well for me. I have a big house, but really just need the fridge, small freezer, coffee pot, sewer pump, and during hurricanes, a small roll around AC unit that I have. During power outages, the humidity is enough to kill a Californian, so I have to have the AC unit working! I can situate myself in a small area with the AC unit and the coffee pot, and read a book until the power comes back on. But for everyday, I would like to run the freezer, TV, computer and one or two lights off of solar. If I can do it, the refrigerator would be nice too. That way my commercial AC bill would be mainly for the house AC system. Do you think that is doable with the Morningstar TS 45, a 24 volt interter, and my existing panels and batteries? I can get more panels just like the ones I have if need be after I get the basic system set up.

    Lucent
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Basic Panel Question
    Lucent wrote: »
    One final question.... when wiring the panels, I understand that the cables to the controller need to be the same length and guage. Do all the cables from each panel to the Combiner need to be the same length also?

    No, it's the cables to parallel batteries that need to be matched. The wiring from the modules to the CC doesn't need to be matched, only large enough to avoid excessive voltage drop.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Basic Panel Question
    Lucent wrote: »
    I can situate myself in a small area with the AC unit and the coffee pot, and read a book until the power comes back on.
    Sounds like a plan! If you are really concerned about power for a long haul (Katrina style?) then I would look at generator for running the AC and coffee pot if the outage extends more than one day or the storm messes up your panels. (They were on the roof when it blew off?)
    The batteries are more likely to stay in one place. :-)
    SMA SB 3000, old BP panels.
  • PhotowhitPhotowhit Solar Expert Posts: 4,994 ✭✭✭✭
    Re: Basic Panel Question
    Lucent wrote: »
    ... I have a big house, but really just need the fridge, small freezer, coffee pot, sewer pump, and during hurricanes, a small roll around AC unit that I have. During power outages, the humidity is enough to kill a Californian, so I have to have the AC unit working! I can situate myself in a small area with the AC unit and the coffee pot, and read a book until the power comes back on...

    Having moved from north Florida, it might be cheaper to move than to run those loads on a backup system!!!

    My minimal 24V system for running a small window A/C unit 4-5 hours a day, is a 1700 watt array, and that's A/C and a minimal fridge in a particularly well insulated room. Most of those roll around units use more watts and are less effiecent. So if your looking at day long outages, you'll need a larger system.

    If your meter is just a basic electric meter it won't help figuring loads over time, things that work on thermostats, fridge, freezers, A/C don't draw a steady current so a snapshot of their use doesn't help.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Basic Panel Question

    Here is a 24 volt Inverter/Charger TSW (True Sine Wave) from Magnum that does 120/240 VAC--Not cheap, but a well integrated unit:

    Magnum Energy MS4024PAE 4000 Watt Sine Wave inverter 120/240 Volt for around $2,200


    It is about the smallest/cheapest solution in a nice/reliable 120/240 VAC package I have seen (probably will want to look at the programming/remote display too).

    Regarding using a generator for long term off grid power--I would see if you can justify a Honda eu2000i (1,600 watt) gasoline genest. Pretty fuel efficient and will support a single 15 amp 120 VAC. There are propane conversion kits too.

    You can use it to power a small 1-room A/C, and keep the battery bank charged (if you don't have solar panels yet, or the blew off in a storm).

    A second, larger genset is also a possibility for larger loads (house A/C, shop tools, deep well pump), and as a backup to to the smaller genset.

    Choosing your backup fuel source (propane, diesel, gasoline) will be important too.

    Note that a small genset may run on 2-4+ gallons of fuel per day (the 1,600 watt Honda inverter/generator). A large 10 kW genset may run on 1-2 gallons of fuel per hour.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Basic Panel Question
    Lucent wrote: »

    I just watched a video on the Morningstar TS 45, I think the TS 60 is probably too big for what I need..

    Lucent
    CAUTION! It's not the Morningstar TS-45 or the TS-60 that you need, it's the TS-MPPT-45 or the TS-MPPT-60 that you need. The first two are PWM controllers, same type as you already have. If you're going with Morningstar, you need one of the second two, the MPPT models.
  • LucentLucent Registered Users Posts: 8
    Re: Basic Panel Question
    CAUTION! It's not the Morningstar TS-45 or the TS-60 that you need, it's the TS-MPPT-45 or the TS-MPPT-60 that you need. The first two are PWM controllers, same type as you already have. If you're going with Morningstar, you need one of the second two, the MPPT models.

    Yes, I just didn't put the MPPT in my writing. The video I watched was for the MPPT models. I will be sure that I get MPPT when I order. Thanks
  • LucentLucent Registered Users Posts: 8
    Re: Basic Panel Question

    Bill,
    I have a Yamaha EF2800i with the propane conversion kit which I bought just after I arrived in Fla. when we had those bad hurricanes. I have only had to use it once since then, but had a plug-in for it installed on the side of the house and there is a panel next to the main electrical panel where I can switch over to select outlets. I also had a surge protector installed on the main panel. I powered everything I needed with the generator, except the roll-around AC and the freezer which I hadn't yet bought at the time. I even had a 200 ft extension cord strung to the old folks next door so that they could have a coffee pot and light! It ran for a long time on the 5 gal gas tank. I have since bought the conversion kit and 2-50 pound propane tanks which I have as stand-by. Of course, as it always goes, I haven't had to use any of the emergency stuff again since I spent all the money! But, there's no way around it.....we will have more hurricanes or a possible financial collapse where I will again need it. If I have to use the generator for the roll-around AC, then so be it, but I sure hate the noise, and I would need it round the clock as the nights are muggy and hot, especially during hurricanes.

    I will check out the Magnum Inverter....

    As for my solar panels....I had them installed pretty low to the roof (I traded off panel efficiency for safety) and the roofer who did the work assured me that the whole roof would have to go to get those panels off. But, I have also been thinking of a way to cover them when needed with half inch plywood which would be secured to the roof via galvanized pipe and some sort of hold downs. Still thinking about that tho. There's not much solar in these parts mainly because we have the bad weather and lots (and I do mean lots) of very tall trees. I had my trees trimmed 2 years ago to cull the bad branches and get them away from the chimney and the rest of the house. Why my house has a fireplace in this hot/humid climate I don't know! But the trees do not interfere with the solar panels after about 8 A.M. thru to about 5 P.M.

    So, you think I should go ahead and get the Morningstar MPPT 45? Do you agree that the 60 amp unit is larger than I need?

    I still would like to, down the road, use my existing electronics for a separate system to power the water pump. I think the Sunforce Inverter could handle the surge from the water pump, but again, it's 12 volt. The garage roof is oriented perfectly for panels too.

    I don't think I told you, but I have room on the roof for 6 more panels which I would consider later after we get the basic system working. I want to make sure what I do buy will be able to handle a larger load.....so that I am not restricted in adding smaller appliances down the road.

    Bill, it's really great of you to help me and I can't thank you enough. I did check out the battery hook-up website you recommended. I have my working 4 batteries wired for 12 volts and the leads come off opposite ends to the controller.

    Incidentally, I used an average of 1320 Kw h per month last year. I didn't have the freezer then. I am pretty frugal, yes? I also had to replace the house AC compressor with a 1 ton larger one and have put on a new roof which has cooled off the attic a bit.

    I am using my Kill-a-watt meter getting the data on the freezer.

    Lucent
  • PhotowhitPhotowhit Solar Expert Posts: 4,994 ✭✭✭✭
    Re: Basic Panel Question
    Lucent wrote: »
    So, you think I should go ahead and get the Morningstar MPPT 45? Do you agree that the 60 amp unit is larger than I need?

    It maybe larger than you need, but it would offer some expansion and flexability. If your computer savvy you might look into a Midnite Classic Lite. for $500 delivered(I think they still ship for free) It would off lots of room for expansion and can be setup and monitored via computer(network) for all the advanced features of the regular classic.

    P.S. hard to say "I am pretty frugal, yes?" in this crowd, lots of people here have 'gone native' my proposed 11-13KWh a day looks pretty dang wasteful with this bunch.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • LucentLucent Registered Users Posts: 8
    Re: Basic Panel Question

    Bill,
    Well, I have the Kill-a-Watt reading for the freezer...it is 0.71 KWh. That's about par with a 100 watt light bulb. As stated previously, my average KWH per month last year was 1300...since then I have added a freezer and increased size of AC compressor by 1 ton.

    Here's where I stand now:
    New inverter: Magnum Energy MS4024, 4000 Watt Sine Wave Inverter $2,079.20
    New Controller: Morningstar TS-MPPT-45 $400.00

    I have a propane generator to charge the batteries when needed.
    I have 3 Mono Panels at 36V at 195 watts each.
    I have 10-6V 189 Ah batteries of which I can use 8 for 24V controller.

    I chose the inverter that does not have 240 V capability.....don't see why I need it. I have 240 on the propane generator. It's less than $100 more for the 240, but don't see the need.

    I will use existing 12 V PWM controller, left over batteries (2) and Sunforce 12V 4800 W inverter for
    well pump. Will need new panels and more battery storage.

    I will see how main system performs and add additional panels as necessary. I hope to be able to run the freezer, a couple lights, toaster, and maybe refrigerator on system for starters.

    I would like to cut over the TV and Computer to solar in the future.

    Is it time for me to place the orders for the new electronics, or do we need more usage data?
    I am presently collecting data on the refrigerator.....I need a new refrig. as the one I have is
    quite old. Yes, I always buy Energy Star when possible.

    Any thoughts?

    Lucent
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Basic Panel Question
    Lucent wrote: »
    I would like to cut over the TV and Computer to solar in the future.
    ....
    Any thoughts?

    Lucent

    For you and others in the same boat, a quick summary of important points:

    If you have the opportunity when buying a new computer or TV, look for a computer which has a low energy consumption mode. Laptops have this as a matter of course, but some desktops also have setup options for power consumption which can reduce the drain when the computer is on but not doing much work.
    For TVs, LED backlight is comparable to fluorescent backlight in energy consumption but has the advantage that it can dimmed or switched off more easily. I have heard the assertion that plasma is even more energy efficient because only the lit portions of the image take energy. But that would probably be the last tie-breaker criterion I would use when buying a TV!

    For your existing TV and computer, look at reducing the backlight level to the minimum you can put up with on the TV and engaging any energy saving options you can find on the computer.

    Unless you need to be able to turn on with the remote, consider putting the TV on a power strip or switched outlet to remove the sometimes substantial parasitic drain of the standby circuitry.

    Regarding the refrigerator,
    take a look at the published information from Consumer Reports regarding the apparent fudging of Energy Star test conditions by LG and possibly other manufacturers.
    Just about any new refrigerator will have better insulation than an older one.
    Look out for frost-free: In many cases the defrost timer is set to run more frequently than really necessary, and this is not user-adjustable (replacing the timer is often the only option, but you may be able to override the timer with a manual switch).
    Turn off the optional door gasket heaters unless the sweating is totally intolerable.
    SMA SB 3000, old BP panels.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Basic Panel Question

    Unless there has been a drastic change in plasma TV's in the last year, they are energy hogs compared to LED. Even walking past a display of different types of TV's, I can easily pick out the plasma's by the feeling of heat on the side of my face as I walk by. I know they've been working at improving their energy hog image, so perhaps things have changed for the better, but I'd want to see it on a Kill-A-Watt before I purchased. Another point, the plasma screen have the reputation of relatively short life compared to LED. Again, I'm sure they must have been working on that as well, but I have no proof one way or the other.
    Some of the hi-end LED TVs shut off the LEDs behind areas of the picture that are supposed to be black, reducing power consumption and increasing contrast. Many however are "edge lit" with LEDs that are always on.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Basic Panel Question
    Unless there has been a drastic change in plasma TV's in the last year, they are energy hogs compared to LED. Even walking past a display of different types of TV's, I can easily pick out the plasma's by the feeling of heat on the side of my face as I walk by. I know they've been working at improving their energy hog image, so perhaps things have changed for the better, but I'd want to see it on a Kill-A-Watt before I purchased. Another point, the plasma screen have the reputation of relatively short life compared to LED. Again, I'm sure they must have been working on that as well, but I have no proof one way or the other.

    Tests from 2010 confirm your observation, although the (manufacturer-predicted) improvement rate of 30% per year on the plasma side may have reduced the difference from 200% to only 70% by now.

    From http://reviews.cnet.com/green-tech/tv-power-efficiency/:
    Average plasma: 301 watts
    Average LCD (standard): 111 watts
    Average LCD (LED): 101 watts

    For all types, power consumption is roughly proportional to screen area.

    Also note that TVs in the store aisle are operating in retail mode, otherwise known as "torch" mode, and will all be noticeably worse in both power consumption and life than the same TVs in consumer mode.
    SMA SB 3000, old BP panels.
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Basic Panel Question
    Lucent wrote: »
    Bill,
    Well, I have the Kill-a-Watt reading for the freezer...it is 0.71 KWh. That's about par with a 100 watt light bulb. As stated previously, my average KWH per month last year was 1300...since then I have added a freezer and increased size of AC compressor by 1 ton.

    For a "smaller off grid system"--I usually suggest around 3.3 kWH per day / 100 kWH per month as enough power to live a fairly "normal" electrically powered existence. That is (very roughly) a Fridge, lighting, efficient TV/Radio/Laptop, clothes washer, and domestic well pump. Off grid solar is still pretty expensive power--so unless you have needs for more power (in a region that needs A/C, run a business, etc.) that is a pretty capable.
    Here's where I stand now:
    New inverter: Magnum Energy MS4024, 4000 Watt Sine Wave Inverter $2,079.20
    New Controller: Morningstar TS-MPPT-45 $400.00

    I have a propane generator to charge the batteries when needed.
    I have 3 Mono Panels at 36V at 195 watts each.
    I have 10-6V 189 Ah batteries of which I can use 8 for 24V controller.

    Normally, I really suggest designing for a known load--If the system cannot keep your loads running--you will not be happy.

    But, for emergency systems, you can certainly make up for a lot of "unknowns" with a backup genset and fuel supply.

    So--The next choice to design a system is around the battery bank--Unhappy batteries (too much load/inverter, not enough charging sources, etc., can give you short battery life.

    In your case, 8x189 AH x 6 volt batteries configured in a 24 volt battery bank (I forgot if these are AGM or flooded cell--AGM have higher surge current and less self discharge--But designing for a flooded cell bank will still give you a nice system for using AGM too). Start with the 5% to 13% rate of charge:
    • 8*189 AH * 6 volts * 1/24 volt battery bank = 378 AH @ 24 volts in two parallel strings (use this website for wiring suggestions):
    • 378 AH * 29 volts charging * 1/0.77 controller+panel derating * 0.05 rate of charge = 712 watt array minimum
    • 378 AH * 29 volts charging * 1/0.77 controller+panel derating * 0.10 rate of charge = 1,424 watt array nominal
    • 378 AH * 29 volts charging * 1/0.77 controller+panel derating * 0.13 rate of charge = 1,851 watt array "cost effective maximum"

    A 45 amp MPPT charge controller on a 24 volt battery bank will support a (cost effective) maximim solar array of:
    • 45 amps * 29 volts charging * 0.77 panel+controller derating = 1,005 watt array (cost effective) maximum

    So, what size array are you thinking about?

    Lets say you are near Jacksonville Florida, using PV Watts for fixed array, tilted to latitude, and 0.52 derating for an off grid system, we get:
    Month    Solar Radiation (kWh/m 2/day)
    1      4.29     
    2      4.31     
    3      5.41     
    4      6.10     
    5      5.82     
    6      5.50     
    7      5.44     
    8      5.37     
    9      5.13     
    10      4.81     
    11      4.51     
    12      3.77     
    Year      5.04
    

    Tossing out the bottom three months (assume generator to support during bad weather/winter), the above suggested arrays would produce:
    • 712 watt * 0.52 system derating * 4.31 hours of sun (February) = 1,596 WH = 1.6 kWH per day (February average)
    • 1,424 watt * 0.52 system derating * 4.31 hours of sun (February) = 3,191 WH = 3.2 kWH per day (February average)
    • 1,891 watt * 0.52 system derating * 4.31 hours of sun (February) = 4,145 WH = 4.1 kWH per day (February average)
    I chose the inverter that does not have 240 V capability.....don't see why I need it. I have 240 on the propane generator. It's less than $100 more for the 240, but don't see the need.

    The 120/240 VAC is purely a personal choice. If you have a 240 VAC well pump (or smaller 240 VAC A/C system) and/or need to send a fair amount of power way across your property--bumping the voltage to 240 VAC is pretty nice (smaller wire, less losses, no transformer cost/losses to up voltage for well pump, etc.).

    Back to the battery bank--Suggested supported power levels. C/8 (8 hour discharge rate) and C/2.5 for surge loads are good numbers for maximum sustained power:
    • 378 AH * 24 volts * 0.85 inverter eff * 1/8 rate of discharge = 964 watt sustained 120/240 output
    • 378 AH * 24 volts * 0.85 inverter eff * 1/2.5 rate of discharge = 3,084 watt surge 120/240 output (starting well pump, etc.)

    Your 4kW inverter is a bit on the "large size"--It can supply more power than would be recommended for your size flooded cell battery bank--So don't overload the bank/inverter (this is sort of typical, as you go up in inverter input voltages, the "high function" inverters and inverter/chargers tend towards the higher wattages--I would like to see more choices for smaller 24/48 volt inverter/chargers as not everyone is going to have a huge battery bank and solar array).

    To finish the discussion, there is the question of your propane genest and AC battery charging. Again, the 5 to 13% rate of charge is recommended, but many times a 25% maximum charge controller is what is available--Is OK but a bit on the large size (charging a flooded cell battery bank from 20% to 100% State of Charge with a >13% rate of charge can overheat--So watch battery temperature and get the remote battery temperature sensor option if available). So, charger rating in Amps:
    • 378 AH * 5% = 19 amps @ 24 volts minimum
    • 378 AH * 10% = 38 amp nominal
    • 378 AH * 13% = 49 amp healthy maximum
    • 378 AH * 25% = 95 amps maximum recommended

    The MS 4024 has a 105 amp maximum output charging current (should be programmable for less) and a remote battery temprature sensor option (get it).

    So, at maximum output current, your AC genset would need to have a rating of (assuming 105 amp output):
    • 105 Amps * 29 volts charging * 1/0.85 charger eff * 1/0.95 power factor = 3,771 watts minimum estimated genset rating (unless max charging current is reduced)

    Note that I am a big believer in "balanced" system design. A large genest (say 10kW) can use upwards of 1-2 gallons of propane per hour (guesstimate--supporting a 0-5kW AC load). A Honda eu2000i running a 20 amp @ 24 volt charger would be closer to 1/8 to 1/4 gallon (gasoline) per hour.
    I will use existing 12 V PWM controller, left over batteries (2) and Sunforce 12V 4800 W inverter for well pump. Will need new panels and more battery storage.

    This may not work at all--Such a small battery bank will support a starting surge of around:
    • 198 AH * 12 volts * 0.85 inverter eff * 1/2.5 max surge = 808 watt maxijmum surge

    And a 4.8 kW AC inverter on such a bank is way oversized. And probably wastes a lot of power running the switches/transformer. A MorningStar 300 Watt TSW (600 watt for 10 minutes) 12 volt inverter would be a much better match--But, again, would that run your well pump?

    Is that enough for your pump?
    I will see how main system performs and add additional panels as necessary. I hope to be able to run the freezer, a couple lights, toaster, and maybe refrigerator on system for starters.

    A toaster is still a bit much for your system--it will run it, but it is a bit hard on the battery bank.
    I would like to cut over the TV and Computer to solar in the future.

    Is it time for me to place the orders for the new electronics, or do we need more usage data?
    I am presently collecting data on the refrigerator.....I need a new refrig. as the one I have is
    quite old. Yes, I always buy Energy Star when possible.

    So--what is your solar array size? What is your power needs--For emergency systems (or weekend cabins/homes, etc.), frequenty we are limited by other things (roof array, amount of savings, etc.).

    Given the blizzard of numbers above--How do they line up against your expectations/needs/financial resources?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Basic Panel Question

    it might be good for me to mention that solar guppy found that he benefited from aiming just slightly east of south due to the fact he had many storms in the afternoon times. i would suspect most of florida to be similar to his findings, but i don't remember how far off to the east he went with it. who knows as you will be near the ocean and may get more diffuse sky radiation from the reflections off the ocean too.
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