Getting started with PV solar

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I am getting started in PV solar here in Cincinnati O and relay have no body to talk to .... My plans at this time is to take  two household circuits, living room TV and furnace blower motor 1/3 hp, and put them on solar just in day time... All I see is "battery- battery's" ..  why can't I put the inverter/s directly on to the 12 V  solar panels??? The bad thing is that I see is when the load drops off of the inverter, the load on the panels will also drop off causing the panels voltage to go higher and may be cause the inverter to drop out on "high in put voltage" I have other questions but let be the start...   Can somebody help me.... Thanks Ted :-(

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,478 admin
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    Re: Getting started with PV solar

    Techinically, it is possible to connect solar panels directly to an inverter--but practically it is not a very satisfactory solution. Basically, solar panels output exactly what the sun is shining. Cloud goes by, the panel drops by 1/2 or more in output current capability.

    The standard inverter wants to supply a steady 120 VAC 60 Hz (US voltage/frequency) to what ever the load requires (fridge, TV, etc.)...

    Problem is that if the load is greater than the input power of the solar panel, you get a brownout (and damage the appliance--especially if it is a motor) or simply an on/off AC power to the device--not very useful or practical.

    If you want pure solar power--it is generally better to connect simple DC devices to the solar panel and run the, for example, solar water pump slower, or if a DC boombox the music will drop out if the sun is blocked to the solar panel.

    For you home... Most cost effective is the "Grid Tied Inverter System". It, basically, uses the Utility AC Grid as a giant battery unlimited battery. However, there are issues (first is that this requires permits, second, not all utilities allow grid tied inverters or support net metering).

    I have to go right now, but this is a start... You have to have an idea of how much money you wish to spend and what type of solutions do you want (best price, AC power if lights go out, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
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    Re: Getting started with PV solar

    Be aware that most 1/3 HP motors draw a lot of power, but you're speaking of "getting started".
    Unless you have lots of money to purchase enough panels to supply the motor, you'd be better off switching other loads to solar, such as lights and other small loads, if you are just wanting to get started.
    Re the TV: The newer LCD ones are relatively easy on power, especially the smaller ones, but the older ones tend to be energy pigs by comparison.
    There, I've said my piece.
    Many of us learn the hard way.
    Good luck
    Wayne
  • System2
    System2 Posts: 6,290 admin
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    Re: Getting started with PV solar

    Thanks Bill for your fast response… Yes, the best is the grid tie in so I can swing back in forth from grid to PV,   BUT  the cost is tooo high.  My first vision was two separate circuits… Living room TV  #1 , and the #2 was the furnace blower motor…..  Just for day time…9- 4 Pm..  I think I want to stick with this concept at the start. I have both the abilities for mechanical and electric/electronics ( some of my ideas scare me)..

    At the present time I have about 75w ( 12v) of PV.  At the present time I  have enough “cells” to make 2 more 36 cell panels. 
    1. The living room TV = 100 +- W.  /  2 – 75w bulbs ( not on in day time when sun is out) = 250W max (get by on 125W ?)
    2.  The furnace blower motor is 1/3 hp = 479w  (./. 120= 4A),  inrush amps=  10a??? for about 2 sec.
    3. I have a 2400w portable gas gen.

    I was thinking about  buying 2  inverters until I started to price them, I came to the idea of One - 1kw inverter  such as Samlex 1000 Watt 12 Volt Sine Wave from Win-sun . Does this sound logical? .  I could run 2 circuits off of the same inverter assuming I have enough 12v input PV power .   And having ( at start) One deep cycle 12v batt. Led-acid….from a local battery company. ( charging batt.—another discussion )

    Bill, could you advise me of what  kind of controller/charger to purchase,, it would need to be able to sense temperature  because the Batt. Will be on the patio out side. 
    Thanks for your help..  Ted gb
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
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    Re: Getting started with PV solar

    Silas, if you are just getting started and are into 'ideas' try this site.

    http://p198.ezboard.com/bleadacidbatterydesulfation

    There are sure to be some thiings to get you thinking...

    Cheers Eric
     
    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
  • System2
    System2 Posts: 6,290 admin
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    Re: Getting started with PV solar

    Cheers, I am new to a forum, just found this this month...... My Reply #3 on: June 17, 2007 i was looking for help on what I have and consept of what to do..... at this time there were just a couple of people who read my messages, sense then 197 has read them and no one has sent help.... What did do wrong that no body has reached out to advise me???? Ted
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
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    Re: Getting started with PV solar
    Silas683 wrote:
    What did do wrong that no body has reached out to advise me???? Ted

    not so much wrong, but you've asked a question that's tough for us to figure out how to answer.
    Earlier answers would still apply.

    Storing batteries outside on a patio is not recommended.

    If just wanting to try to power a few small lights from solar, maybe a battery and inverter works, but trying to create a solar panel out of individual cells is not going to have good long term results. They cost a lot for a reason, lots of high reliability connections cell - cell in extreme environments is tough.

    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.
    BB. Super Moderators, Administrators Posts: 33,478 admin
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    Re: Getting started with PV solar

    Partly, I was in a rush at the time and forgot about your request--the other was I really did not know how to answer your questions/statements.

    More or less--you have a lot of loads, a large inverter, very little solar PV panel power and not a lot of battery storage. Plus it sounds like you are making your own solar panels?

    Basically, I would suggest that you look at your solar loads and understand how many Watt*Hours of energy you want to use--and how much you want to offset with solar panels.

    Realistically, just as a SWAG, your 75 watts of solar will probably run just your TV for 1-2 hours a day. And, if you have a standard automotive sized 12 volt storage battery, it would reliably run the TV for about 4 hours (assuming you recharged the battery with solar + generator).

    Your 1kW inverter will discharge a typical 100AH 12v storage battery in about 1/2 hour (for long battery life--discharge only to 50% of capacity). If you ran the 1kWatt inverter at full power for 1 hour, it would kill the battery within a few days or weeks of use (discharge/charge cycle).

    So--Two places to start--One is you need to measure how much power you want to run on solar/generator by using a kill-a-watt meter or equivalent.

    http://store.solar-electric.com/kiacpomome.html (from here or equivalent)

    Do you understand how voltage, current power, and energy are measured?

    Power=Volts * Amps
    Energy=Watt*Hours=V*I*Hours
    kiloWatt*Hours = Watt*Hours/1,000 (kWh is the unit of power your utility charges for electricity. Typically about $0.10 to $0.35 per kWhr).

    So, example: TV watt * Time = 75 watts * 2 hours = 150 watt*hours or 0.15 kWhrs (about $0.001 of electricity).

    Heater Energy = 479 watts * 2.4 hours / 24 hour day (10% cycle) = 1,149.6 WHrs / 24 hours = 1.1kWhrs /day

    And so on... Remember that measuring actual power used rather than just nameplate ratting is much more accurate. Also, duty cycle for some appliances (like fridge/freezer/heater) also is important.

    Just as a first guess, your solar panels will average something like 2xRating worth of usable energy per day because of inverter, charger, and battery losses. So, a 75 watt panel * 2 hours will give, very roughly, about 150 Watt*Hours per day of usable energy (150 watts for 1 hour or 10 watts for 15 hours, etc.).

    You will find that with solar, conservation of power is very important... For example replacing two 75 watt bulbs with two 12 watt CFL's would be top on the list.

    Sorry--family is calling again--but does this give you some ideas of what more is needed to really help?

    -Bill

    PS: just to finish the thought...

    2x75w*4 hours = 600 Watt*hours
    2x12x*4 hours = 96 Watt*hours

    So, in this example, your system would easily run two CFL's with energy left over. The other 75 watt bulbs--your system could only run them for about 1 hour (assuming filament 75 watt bulbs vs 12 watt CFL's--obviously, I don't know your home/usage).

    Also, solar does vary over the seasons (and by weather, location, mounting angle, shade, etc.) and you can get more than 150 watt*hours from your 75 watt panel (and you can get less)--but it is a good place to start without losing everyone in the math and other issues (battery choice, charger choice, inverter choice, wire choice, etc.).

    I suggested Grid Tie as an alternative because the batteries, losses, additional equipment, etc. usually make Grid Tie less expensive over the long term on a $/kW costs (other than using electricians/permits required for Grid Tie). Unless you need off-grid power (for storms, cabin, etc.) and you need a battery based system.

    -BB
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • fatheadl
    fatheadl Solar Expert Posts: 31 ✭✭
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    Re: Getting started with PV solar

    Hi all,
    Storing batteries outside on a patio is not recommended.

    Why is this not recommended?

    fatheadl
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
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    Re: Getting started with PV solar

    "Outside on a patio" often means an uncontrolled thermal environment. Cold batteries temporarily lose considerable capacity (figure on ~1% loss for every 1 degree C below 25 C), and their charging voltages require considerable temperature compensation. Specifically, a battery at 0 C / 32 F can deliver only ~75% of its rated capacity, and the absorption charge voltage for a typical 12 V battery must be increased from ~14.4 V to ~15.15 V.

    Conversely, elevated ambient temperatures typically shorten battery life (number of cycles), and the charging voltages for hot batteries must be reduced.

    Finally, batteries are dangerous devices, and not only should inquisitive people be protected from batteries, but batteries should also be protected from inquisitive people.

    HTH,
    Jim / crewzer
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Getting started with PV solar
    Silas683 wrote:
    Cheers, I am new to a forum, just found this this month...... My  Reply #3 on: June 17, 2007 i was looking for help on what I have and consept of what to do.....  at this time there were just a couple of people who read my messages, sense then 197 has read them and no one has sent help.... What did do wrong that no body has reached out to advise me????  Ted

    i agree that batteryless grid tie is the way to go in your case and there's no need to seperate those particular circuits as long as you buy enough pvs to cover what those circuits draw.
    as to answering your question, it was answered, but it seems you don't want to hear the answer for some odd reason. is it that we are missing what you're asking or are you missing what has been said?
    as to the number of hits for your posted question, many times guests of the forum read it and it registers as being read. trouble is, they are not able to post as guests and maybe, just maybe, they are looking with interest on that question to learn from it as you are supposed to be trying to do. also, when you check on it 15 times per hour it registers as being read 15 more times.
    or is it that i told you about using the 'report to the moderator abuse/problem option' as a means of general communication to a moderator and you are mad that i told you that you can't do that and you have to use the pm? we are flexible here, but you are starting to annoy me in that you have a 'more special than everybody else attitude'. 'poor me' routines irk me when they are unfounded. :x
  • System2
    System2 Posts: 6,290 admin
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    Re: Getting started with PV solar

    Neil, QRZ, "i told you that you can't do that and you have to use the pm? " What is " pm"??? I am soyyr that I do not know what to do! this ios my first time on a forem and if i do not know how to use it i am sorry.... Ihave no one to help me...... i ask a question about .... never mind good by 73's ted
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Getting started with PV solar

    i had sent you an email as well as given you a pm (private message). bye, your choice.

    Date: Mon, 25 Jun 2007 09:17:43 -0700 (PDT)
    From:  <n3ghxatyahoo.com>  Add to Address Book  Add Mobile Alert 
    Subject: from niel on the naws forum
    To: ********@earthlink.net
        ted,
    please log onto the forum and look at the top where it says messages. you will see total messages and the number of new messages there for you. please click on messages to bring up something important for you to read from me via private message or pm. to insure that you read it is why i have sent this to you via your email address that i became aware of when you made a report of abuse. do not be alarmed as it is safe with me and you are not in trouble.
    niel

    want the pm here too?