Where to start?

KrakenZKrakenZ Registered Users Posts: 5
Hello all,

As my first post, I would like to introduce myself and get some advice on how to get started in solar. I'm an average Joe looking to have fun with solar and with a limited budget at this time, would like to get started in an off-grid setup. I don't have the time or money to invest in a full grid system but would like to experiment with a kit and see where it takes me.

I know a lot of folks started off with one of the 45w kits from harbor freight. I would probably want to get started with a 100w kit, since that seems to be more economical and functional for small lighting fixtures and small electronics.

I have done some research before coming here and know that if I become serious with solar, it won't be a cheap investment but at this time I would like to try out a single panel system with a PWM or cheap(ish) MPPT charge controller and a few battery banks. Again, I'm looking for a starting point with as little of an initial investment as possible since I'm not sure if it will be something I will expand upon or not at this time.

If there is a kit (excluding batteries) around the $100 range, that would be excellent. I understand that there are different batteries and prices and lives of batteries and a whole list of things to sort out on that front, so advice on a good starter battery that won't break the budget would be greatly appreciated.

Again, I come here from having little to no knowledge about the systems and hope that some helpful and friendly advice can guide me to make a good investment decision on my first setup.

A bit of info for reference, I live in South Carolina and have my home with the front slope facing due north and the rear slope facing due south. I would like to set up in the back since due south appears to be the best place to have panels. We get a good amount of sun throughout the spring and especially the summer months, so I'm hoping the location would present a nice reward in solar investment.

Thanks in advance!

Comments

  • JoshKJoshK Solar Expert Posts: 232 ✭✭
    Welcome. I'm a beginner too... I read your post and thought, if you are considering a larger system, maybe you want to "test drive" a particular panel before you buy a whole system. I mean you could choose your first panel based on the criteria of the system you are dreaming of, so later you don't buy thousands of dollars of panels you have never tested.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    For prices of the pieces look at our sponsors store, they have good pricing and service...
     
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  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Two ways to design an off grid solar system:
    1. Based on your loads (voltage, Amp*Hours or Wat*Hours per day)
    2. Based on a major system component (have battery, or have solar panel)
    Just to give you some ideas... A 500 Watt*Hour per day system is actually quite capable. Can run a laptop computer, a few lights, charge some cell phones. A 500 Watt*Hour system would look like (using our basic rules of thumb for a reliable off grid system with good battery life--Full time use).

    A battery that can supply the load for 2 days of bad weather and a maximum of 50% discharge:
    • 500 Watt*Hours per day * 1/0.85 AC inverter eff * 1/12 volt battery bank * 2 days storage * 1/0.50 maximum discharge = 196 AH @ 12 volt battery bank
    Two x 6 volts @ ~200 AH batteries in series is a very nice bank.

    To select the solar array, there are two calculations. One based on the size of the Battery Bank. The second based on hours of sun per day.

    First, we charge the battery bank at ~5% to 13% rate of charge with solar:
    • 200 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.05 rate of charge = 188 Watt array minimum (weekend use)
    • 200 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 377 Watt array nominal (full time)
    • 200 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.13 rate of charge = 490 Watt array "cost effective" maximum
    And based on hours of sun per day and your loads. Using PV Watts for Columbia SC, fixed array, tilted to 34 degrees from horizontal:



    Month
    Solar Radiation
    (kWh/m 2/day)


    1
    3.81


    2
    4.48


    3
    4.98


    4
    5.95


    5
    5.66


    6
    5.81


    7
    5.65


    8
    5.41


    9
    5.38


    10
    5.71


    11
    4.54


    12
    3.80


    Year
    5.10



    If you want to "squeak by" in winter:

    500 WH per day * 1/0.52 system eff * 1/3.80 hours of sun per day = 253 Watt array minimum

    And get a nice 300 Watts 12 VDC AC inverter with remote on/off and "search mode" (low power standby)... The basic system.

    I know this is much larger than you have planned on--But it does give you the basic math/information needed to size a system.

    Your questions/thoughts?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • scrubjaysnestscrubjaysnest Solar Expert Posts: 175 ✭✭✭
    BB. wrote: »
    :
    snip................Just to give you some ideas... A 500 Watt*Hour per day system is actually quite capable. Can run a laptop computer, a few lights, charge some cell phones. A 500 Watt*Hour system would look like (using our basic rules of thumb for a reliable off grid system with good battery life--Full time use).

    A battery that can supply the load for 2 days of bad weather and a maximum of 50% discharge:
    • 500 Watt*Hours per day * 1/0.85 AC inverter eff * 1/12 volt battery bank * 2 days storage * 1/0.50 maximum discharge = 196 AH @ 12 volt battery bank
    Two x 6 volts @ ~200 AH batteries in series is a very nice bank.

    snip
    -Bill
    Bill,
    I missed something here; looks like you need 4 x 6 volts @~200 AH batteries in series/parallel for ~50% discharge. 400 AH*1/0.50 = 200 AH???
  • KrakenZKrakenZ Registered Users Posts: 5
    I don't know if I will be able to convince the wife to let me drop $800 to $1k on a new project. Any idea what I could run off of a pair of 100w panels and a pair of 12v 18ah batteries?

    I would only be using it during the weekends if that makes a difference.
  • JoshKJoshK Solar Expert Posts: 232 ✭✭
    A pair of 12v 18ah calculates to 432 watts DC. After inverter losses that's 367 watt. And that's abusing your batteries. With abuse, 367 watt is about the equivalent of 3 amps wall power. Probably not quite enough to get a high efficiency refrigerator started, but it should run 6 bulbs at 60 watt OR 28 very high efficiency bulbs of 60 watt equivalent.
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Adding batteries in series, the voltage adds:
    • 2x 6 volts @ 200 AH = 12 volts @ 200 AH
    Adding batteries in parallel, the AH capacity adds:0
    • 6 volts @ 2x 200 AH = 6 volts @ 400 AH
    The stored energy is the same:
    • 12 v * 200 AH = 6 v * 400 AH = 2,400 Watt*Hours
    Recommend to not discharge below 50% often for longer life.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BisMBisM Registered Users Posts: 13
    KrakenZ wrote: »
    Hello all,

    As my first post, I would like to introduce myself and get some advice on how to get started in solar. I'm an average Joe looking to have fun with solar and with a limited budget at this time, would like to get started in an off-grid setup. I don't have the time or money to invest in a full grid system but would like to experiment with a kit and see where it takes me.

    I know a lot of folks started off with one of the 45w kits from harbor freight. I would probably want to get started with a 100w kit, since that seems to be more economical and functional for small lighting fixtures and small electronics.

    I have done some research before coming here and know that if I become serious with solar, it won't be a cheap investment but at this time I would like to try out a single panel system with a PWM or cheap(ish) MPPT charge controller and a few battery banks. Again, I'm looking for a starting point with as little of an initial investment as possible since I'm not sure if it will be something I will expand upon or not at this time.

    If there is a kit (excluding batteries) around the $100 range, that would be excellent. I understand that there are different batteries and prices and lives of batteries and a whole list of things to sort out on that front, so advice on a good starter battery that won't break the budget would be greatly appreciated.

    Again, I come here from having little to no knowledge about the systems and hope that some helpful and friendly advice can guide me to make a good investment decision on my first setup.

    A bit of info for reference, I live in South Carolina and have my home with the front slope facing due north and the rear slope facing due south. I would like to set up in the back since due south appears to be the best place to have panels. We get a good amount of sun throughout the spring and especially the summer months, so I'm hoping the location would present a nice reward in solar investment.

    Thanks in advance!

    Hi KrakenZ, I'm new to the forum and solar energy like you and I was about to post a very similar thread to this so I'm glad you beat me to it and already have some good responses!

    My situation it quite similar to yours and I'm wondering if you've found a goody single panel system yet?
  • KrakenZKrakenZ Registered Users Posts: 5
    BisM wrote: »

    Hi KrakenZ, I'm new to the forum and solar energy like you and I was about to post a very similar thread to this so I'm glad you beat me to it and already have some good responses!

    My situation it quite similar to yours and I'm wondering if you've found a goody single panel system yet?

    I was looking on eBay and found what appears to be a good deal on Renogy 100w panels. There is a kit with a PWM charge controller for about $135 w/ free shipping. I would prefer a MPPT charge controller but I think this is the way I'm going to get started. I'll most likely pick this up and see what sort of power I can store to run some things in my garage and see if it will be worth investing further. I also saw a good deal on a 12V 18aH battery for about $25 and was going to pick those up as well. Waiting on next Friday before I pick it up since the bills have to be paid before you can play 8)
  • KrakenZKrakenZ Registered Users Posts: 5
    JoshK wrote: »
    A pair of 12v 18ah calculates to 432 watts DC. After inverter losses that's 367 watt. And that's abusing your batteries. With abuse, 367 watt is about the equivalent of 3 amps wall power. Probably not quite enough to get a high efficiency refrigerator started, but it should run 6 bulbs at 60 watt OR 28 very high efficiency bulbs of 60 watt equivalent.

    I have switched all of my lights out with CFL lights, so hopefully I will only be pulling in 13 watts a piece for those vs the 60 watts that a typical incandescent light would require.
  • JoshKJoshK Solar Expert Posts: 232 ✭✭
    KrakenZ wrote: »
    13 watts a piece

    Yep, I used 13 watt for that calculation. The LEDs I have are 9.5 watt, I meant to use that number but 13w was stuck in my head for some reason.
  • Alaska ManAlaska Man Solar Expert Posts: 252 ✭✭
    Don't bother throwing your money at an E-bay get up. As Bob suggested figure what you want to run, how much power you will need for how long and go from there. Otherwise you will be disappointed with the results. He did all the figuring for ya. Take that and call N.A.W.S, You'll be money ahead that way,
  • JoshKJoshK Solar Expert Posts: 232 ✭✭
    I second Alaska Man's opinion. Anything that small is not going to be worth it and you will have to start over if you go ahead with a better system.
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    If you dont have a budget for a proper system, ( and youll be surprised how all the BOS (bal of system) costs add up when built properly and safely), if you want to experiment, buy a 20W panel off ebay, pick one of the better name brand cheaper PWM controllers, (morningstar are easy to get used), and invest your time in learning the deisgn principles. Save the higher spec gear for a real system, when you know what you are doing.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • JoshKJoshK Solar Expert Posts: 232 ✭✭
    Maybe this thing would satisfy your curiosity and budget. It's a solar panel, battery, and light all packed in a mason jar lid. And you can take it apart and poke it with a volt-meter for fun :) It is $5.90
  • KrakenZKrakenZ Registered Users Posts: 5
    I'm going forward with the plan to get the 100w Renogy panel and found a Morningstar mppt charge controller for around $100, so I'm in $225 so far. I've also go a call into a guy from craigslist for some agm batteries for about $30 each, which looks like an okay deal, so total I'm in with a 100w panel, good charge controller and batteries for $285.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    be very careful of used AGMs as you can not check the SG or electrolyte levels... look for Golf Cart batteries, used even is better...
     
    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
  • Alaska ManAlaska Man Solar Expert Posts: 252 ✭✭
    I was going to buy a pellet stove off of Craig's List. The guy had it in the back of his truck, on a pallet "already to go". I had red flags going up everywhere, who is that prepared in life?

    He wanted to meet me in town for the trade. I said, that's fine meet me at Home Depot so I can bring a chord and plug it into a Head Bolt Heater and at least see if the fan works. NOT another peep out of him. He just dropped off the face of the earth.

    Lot's of CRAP on E-bay being sold as "Slightly Used".
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