So confused! New to solar but need power at the barn.

MDKirksey
MDKirksey Registered Users Posts: 13
I am new to solar but got the chance to by 4-250watt panels from a going out of business sale. They are Sharp ND-Q250F7BX panels. Attachment not found. I also have 2 MPPT 30 amp controllers and 150 ft of 10 gauge wire. 20-12v batteries all the same type and amp Hours with pretty much the same amount of use from each. I want to attach two panels parallel to each controller and run both controllers to the same parallel battery bank. Then off of that run an invertor. I have been told I also need a Busbar? and a capacitor between the batteries and inventor to use a vacuum or other small electrical devices due to the sudden large draw from some devices. Just wondering if there is anything I need to do differently. Or what I could do differently to make this work better. Or if I am even going in the right direction! Help please.

A couple of other questions? The 30 amp MPPT charge control be able to handle 2 - 250 (Pmax)watt panels, 8.9a Isc, 38.3v Voc, 29.8V pmax, 8.4a Ipmax. Not sure about that. (I have one panel hooked up with a 20amp inline fuse to one deep cycle batteries and it works fine)

I understand you can hook up both controllers to one battery bank but do I need to do that a certain way?

Just getting confused. Help would be greatly appreciated. Thanks in advanced. MDK

Comments

  • AuricTech
    AuricTech Solar Expert Posts: 140 ✭✭
    Re: So confused! New to solar but need power at the barn.

    What will your battery bank's nominal Voltage be, and how many parallel battery strings do you expect to have?
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    I am trying to stay with a 12v system and I would put all 20 batteries into the bank if possible or I could make two banks of 10 each I guess.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: So confused! New to solar but need power at the barn.

    Okay the capacitor between the batteries and inverter is useless. Remove it.

    Now, a 12 Volt system. 30 Amps on that is about 467 Watts. Your panels are 250 Watts. If you put two in parallel on each controller you would max out both controllers. They would be 'clipping' about 2 Amps each, which is not a problem.

    How many Amp hours are those batteries? You won't be using twelve of them. Not all in parallel anyway. Your capacity would be limited to 600 Amp hours @ 12 Volts. If you have to make that up from paralleling a lot of batteries, don't.

    If you have not already bought an inverter, skip the 12 Volt system and go to 24. Slightly more efficient and easier to handle all-around. For example one controller would handle all the panels: 1000 Watts * 0.77 / 24 = 32 Amps. Same 2 Amp clip, but on one controller.

    You will need fuse or circuit breaker between charge controller(s) and batteries and also between batteries and inverter.
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    Awesome, I so much appreciate your help. I was planning on putting 12v LED lights up for the barn. Will that still work with a 24 volt system? Also here is an image of the paperwork with the 2 MPPT controllers I have.Attachment not found. (Sorry if the pictures are sideways) Will they work or do I need to get something else? I really do appreciate all the help and information I can get. Thanks again in advance. MDK
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    Not sure the amp hours of the batteries. They were used to run portable equipment at work. They are changed out every 6 months by sop.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: So confused! New to solar but need power at the barn.

    Sideways? It's upside-down. :D

    Anyway the specs don't look very good. Limited input Voltage:system Voltage ratio and no information about charge parameters other than Float Voltage which is not very critical. Absorb Voltage is the important number. I'm going to guess low-dollar no-name controllers originating in China.

    If you are set on 12 Volt loads you really have to stay with 12 Volts. There's ways around it, but they aren't cheap or particularly great (DC-to-DC converter). But if you plan on running an inverter anyway, why not do all 120 VAC loads including lights? There's nothing to be saved by using 12 VDC lights and probably some things to be lost (long wire runs resulting in high Voltage drop, charging Voltage for batteries exceeding safe levels for lights). The right inverter can go into standby when no demand is made and thus reduce power usage when it isn't needed.

    So we really need to know what AC loads you were planning and again what the capacity of the batteries is.

    BTW if those batteries are just sitting around they won't be getting any charge and they will be slowly dying. A boost now and then even with an automotive charger would be a good idea.
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    I will get whatever I need (cost prohibiting of course) to get this going. We basically need lights occasionally and to run things like drills, fans, attic fan, at the most a 110 mig welder, but we also have a generator to do that if needed. I would love to set it up for 110, but figured that would be harder. The nearest electrical line is miles away and at $1500/pole (need on every 50 yards) that is way out of the question!!!! So you got me sold on the ac power already. Just need to know how to set it up. Here is a picture of the same type batteries that a friend has for his cabin. Attachment not found. Sorry again if it is sideways or upside down.
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: So confused! New to solar but need power at the barn.

    Those might be sealed batteries... possibly AGM type/

    What are they used for where you work?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    They run the portable xray machine at a small little hospital.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: So confused! New to solar but need power at the barn.

    No make & model on them?

    Problem is that without knowing the capacity you're flying blind on both charging and discharging. Either of those can be a very unpleasant disaster.

    The next thing you're going to have to address is those loads. How many Watts and for how long? It is essential knowledge for setting up a system that works. Fans, for example, can appear to draw very little power but have a poor Power Factor so they actually use more and over time run up quite a bit of use. For example:

    35 Watt fan. Actually draws 40 Watts. Runs for 8 hours: 320 Watt hours. On 12 Volts (without losses) 27 Amp hours used. That's just one fan.

    The attic fan is bound to be a 1/4HP motor or larger, and that will use quite a bit. In the neighbourhood of 200 Watts all on its own.

    Yes, running an electric service for miles can run into crazy money. $1,500 per pole? Pole every 50 yards? 35 poles * 1500 = $52,500 per mile just for poles. Boy can you build a big off-grid system for that kind of money!
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: So confused! New to solar but need power at the barn.
    MDKirksey wrote: »
    They run the portable xray machine at a small little hospital.

    You should be able to find some info based on who made it and the model etc... Who orders /supplies the replacements? that is another source of info for those cells... I imagine the Xray machine might have an inverter too... Who services the machine also...:confused:
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    I know! They want way to much, Problem is its hilly and so they estimate a pole every 50 yards or so. ( the cost includes the wires and labor putting them up etc. )I have the information coming from my friend that has some of the batteries. He will let me know as soon as he gets home from work so I will pass it on to you. I might have misled you about the attic fan. I'm talking about one that just draws heat from the attic, not one to pull air thru a house. I know I can get one of those with the solar panel attached if I have to for that. Mainly lights, and occasional saw or drill as we work at the barn. I just want to get the right controller, the right batteries and fix this up right. I really do appreciate all the information. You all are the experts for sure. I have been trying to figure this out forever. I have learned more about what I need to do this afternoon, than all the other things I have read, looked up and researched. I am starting to see the light at the end of the tunnel!
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    I got no info on the model of equipment they use, or who orders etc. A friend that has some of the same batteries is going to send me the info when he gets home. I will pass it on as soon as I get it.
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    Here is a picture of the battery. Appears to be only 15 Ah. Maybe this will help. If you need more information, just let me know. Thanks Attachment not found.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: So confused! New to solar but need power at the barn.

    Yes that looks like a 15 Amp hour 12 Volt AGM. Not going to be much good, probably.

    Here's what happens when you put four of these together in a 24 Volt system for 30 Amp hours @ 24 Volts: maximum current draw 7.5 Amps (25%) or about 180 Watts. Maximum Watt hours AC @ 50% DOD 306. Not very much power.

    You have twenty of these. If you put them all together you'd have ten parallel strings (a very bad idea) of two in series for 150 Amp hours. That's a lot of batteries and connecting wires to get not as much power as four GC2's would give you.
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: So confused! New to solar but need power at the barn.

    OK that is a fairly small ( 15Ah)battery listed as an electric scooter bike battery, from its description on the CSB Canada site it says

    EVH-12150 is designed specially for electric vehicles, such as electric golf cart, electric wheelchair, mower, dust collector etc. It has high cycling life, high efficiency and long service life.

    depending on it use, LED lights, you may get some reasonable use but for fans etc it is not a good fit as only 15Ah (per battery) at 12 v = 190Watts derated to 50% (so you don't kill it) = 90 wh, so from 3 you could , max, pull 270Wh.

    http://csb-battery-canada.myshopify.com/collections/evh-series

    this page has about all you will need to know..
    4.5A max charge, is quite low

    http://www.csb-battery.com/english/01_product/02_detail.php

    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    I know, disappointed on the amp hours. What is your suggestion for the most cost effective battery and charge controller to get this system up and going. I already have the 4 panels and just cheap charge controllers (that can be replaced if necessary). I also have 150 foot of 10 gauge PV wire and of course those little batteries that I know won't do much good. I would like to put the panels on the roof and the controllers and batteries inside the barn in an enclosed area (vented of course). I have not gotten an invertor yet. Would appreciate your suggestions for whatever you believe would be the best and most cost effective components for the system. Again I truly do appreciate your time and info.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: So confused! New to solar but need power at the barn.

    Working backwards from the 1000 Watt array you'd get 32 Amps on a 24 Volt system. If you use something like a MidNite Kid it will be clipped at 30 Amps, but it's about $300 less than a larger controller.

    What can you do with 30 Amps? Charge around 300 Amp hours @ 24 Volts. If you want cheap batteries the GC2's are the best bet: four 6 Volt 220 Amp hours, and sometimes available for <$100 at warehouse stores. Definitely shop around. They can handle 30 Amps peak current or you could dial it down a bit with the controller.

    How much power would you have available then? If you stick to 25% DOD you get (55 Amp hours * 24 Volts) 1320 Watt hours DC, or slightly over 1kW hour DC (inverter tare and conversion loss will use some of the power). The good news is that number will improve the more power you can use during the day because you will be able to make use of PV power that otherwise would not be realized.

    The fact is I could squeeze 2.4 kW hours out of my system when it had 700 Watts of PV by doing some careful load management; basically using the batteries for "overnight" power and making use of the PV "surplus" during the day (including running water pump). I have some advantage in elevation which most people don't have (my average derating is 82% not 77%). After I added panels this year and brought the array up to 1200 Watts my record production was just over 4kW hours one day; made possible by utilizing the "surplus" PV power to run construction tools.

    Will this work for you? It's hard to say without any real numbers for the loads. But you'd be amazed how much you can do with that amount of power. There is one caution though: the "small" loads add up over time; my satellite modem & equipment use as much power in a day as the full-size refrigerator does. This is around 1.2 kW hours. The problem is solved by shutting the computer stuff down when sunlight is lost. Having 16 hours in a Summer day is nice too. Having 6 hours in a Winter day is one reason why we aren't there in Winter.

    The inverter choice depends on a number of things. Chiefly the maximum amount of power that will be needed at any given time as it must be able to supply that much. Mine is 3.5kW and yet the kids still managed to pop the fuse on it this Summer somehow. Don't ask me!

    So you could go anywhere from a small Samlex inverter (not the PST series as they aren't good with motors and you want to run motors) like SA-1000K @ $400 to a more robust Exeltech XP1100 @ $800 to a full inverter-charger like and Outback FX2524T @ $1700.

    You need a more specific design to pick the components.
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    Ok I think I'm beginning to understand. So I would need to connect my 4 PVs in series (+ to -) to the charge controller. From the charge controller to the 4 - 6v batteries in series (to make 24v) and the also the load out of the charge controller to the inverter? Not sure how to access the surplus energy from the PVs. Sorry, I am so new to this.
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: So confused! New to solar but need power at the barn.

    down the page a ways are 4 wiring diagrams that may explain just how a solar setup is organized.. should clrify some of your general questions.

    http://www.midnitesolar.com/pages/kid/index.php
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    Thanks so much. Just printed them off. Awesome. I got it now. So we are gonna take these suggestions and go with these components that you all provided. Working on it this weekend. Hopefully last question, am I right about wiring the panels in series which is "+ to -" not parallel which is all the negatives together and all the positives together. (don't want to blow up anything) and then to the charge controller. then the batteries are also wired in series to produce 24 volts. I am excited to get this done. Thanks again for all the help.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: So confused! New to solar but need power at the barn.

    Yes, be very careful about panel polarity... If you connect one panel backwards to a bunch of other panels in parallel, it can be fried very easily (pretty much just like hooking a diode up backwards to a battery--instant fry).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MDKirksey
    MDKirksey Registered Users Posts: 13
    Re: So confused! New to solar but need power at the barn.

    Ok thanks, I will wire the panels in series and connect them to the charge controller and also wire the batteries in series. Thanks to everyone for your help. I will be looking back at the forum often to get more great information, so don't hesitate to give me input on anything you think I should consider. Again, I appreciate all the help. MDK