45 watt system

System
System Posts: 2,511 admin
in Solar Beginners Corner #1
Ok, we have a cabin- 12x32 to be exact. We are completly off grid since we moved and chose not to have power lines run across our land. We have a generator that runs what we need but really want to go solar and wind.
We decided to start experimenting with the solar 1st.
We bought a 45 watt system on sale from Harbor Freight, good price to start playing. We had trouble with the charger/regulator from the beginning.
At first I could run a small fan, dvd player and charge my phone and ipod. Then the charger went, got a new one- never worked like the 1st one, got another- same thing.:grr
I can now only run a small table fan for a little while. The battery is a brand new marine battery. It seems to be charging but dont know.
We were told to check it with a multimeter but we dont know what setting to put it on and the employees were useless. It has DCV, DCA, ACV, and other stuff on it. Seemed simple at the time!!:cry:
I didnt expect alot, as I said it was a good price to start with. But I am confused. I have read the reviews on this system and eveyone seemed to like it except for the charger/regulator. Seems they all say to upgrade the charger.
I have read sooooo much I think I am getting more and more confused.:confused:
Help!
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: 45 watt system

    Welcome to the forum.

    Okay, first thing to do: stop spending money 'til you figure out what to spend it on.

    You have to figure out what you need/want to run and determine how much power that's going to take. Then you figure out how to supply that power.

    Quite a number of people have popped up here complaining about HF panels and cheap charge controllers. Marine/RV batteries aren't a great choice for RE applications either, despite the "deep cycle" label.

    Since you're entirely off-grid, it makes sense to invest in quality equipment to supply your power. Running a generator all the time gets to be expensive and annoying. But it can be a cheap way to recharge batteries for "quiet power" until you can afford enough solar panels to do the job.

    BTW, your cabin is about the same size as my wood shed. :p Hey! It gets COLD in the Cariboo!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,599 admin
    #3
    Re: 45 watt system

    The Harbor Freight 45 watt systems are not the best in the world, and after a few months may have difficulty meeting output power specifications.

    Here is a quick and simple Multimeter Tutorial. You will need to understand how to use them eventually.

    For the meter--if you have it set to VOLTS scale--it is pretty safe to use.

    Do not set it for CURRENT or OHM/RESISTANCE scale until you have further understanding. Those, when connected across a battery can cause you to use your safety glasses.

    Some other training links:

    How to Use Digital Multimeter
    The Basics of Digital Multimeters
    How to use a Multimeter

    And Basic Electricity 101 for beginners? One I found that may be of interest is:

    Electricity for Boaters - BoatSafe.com

    The general problems with lead acid batteries is that if they are over discharged (run to dead) or set below ~75% state of charge for days/weeks/months at a time, they sulfate and eventually loose capacity.

    Some information to read about batteries:

    Deep Cycle Battery FAQ
    www.batteryfaq.org

    What is wrong with your setup--Don't know... But not charging properly and/or using too much power between recharging is a very common mistake--that everyone here has probably made in their early solar/battery powered education.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #4
    Re: 45 watt system

    Thanks for the input!! Will check all this out! Thanks. I am open for more suggestions!!!!;)
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,599 admin
    #5
    Re: 45 watt system

    What I find out that really works well--Define your loads. You can use a Kill-a-Watt meter to measure your small 120 VAC 60 Hz loads... And you can use a Doc Wattson (or similar) for measuring your DC Amp*Hour / Watt*Hour loads.

    Solar PV power + battery banks are not cheap... And most people over estimate how much power they can get from solar and underestimate how much load they have.

    If you are going to be measuring a fair amount of AC and DC current... Getting this little AC/DC Current Clamp meter for ~$60 is a great deal. This one will also do the other DMM type measurements. Of course, you can easily pay $300-$400+ for better quality Fluke meters... But for a start, these inexpensive ones will work "good enough".

    We have more than a few people (me included) that have connected a DMM incorrectly and had a little flash/bang event (amp meters are "dead shorts" and if connected incorrectly, will cause sparks and worse--Near lead acid battery banks, that can cause the hydrogen gas in the batteries to explode).

    A current clamp meter is a much easier/faster/safer way to measure AC or DC current (note, there are a lot of AC only current clamp meters--You need one that does DC too when working with solar/battery power).

    Solar power is expensive for good components, and even less nice components can still end up being costly.

    We will try to work with you so you get some education/understanding of the system you have, and how to work on it first.

    Then you can design your next system and plan your purchases out before spending the next $$ (pretty much everyone here is "cheap";) and hate to see folks waste their hard earned money).

    We have a nice hodge-podge thread here with lots of interesting projects and sources of information:

    Working Thread for Solar Beginner Post/FAQ

    Among the things you may wish to read (in addition to the links already provided):

    For 12 Volt & RV Systems - HandyBob's long discussion and rant is about 99% right on how to make RV and similar 12 volt systems work correctly. One of the few "non NAWS" articles that we recommend.

    Emergency Power

    Basically a very long thread that starts from the beginning with a few vague requirements through design and assembly for a "portable" solar RE off-grid power box.

    And here is another example by Mike90045 called the Solar Monolith:

    attachment.php?attachmentid=384&stc=1&thumb=1&d=1234752636

    attachment.php?attachmentid=385&stc=1&thumb=1&d=1234752653

    Update pictures/information here.

    Here is a nice thread with video from Kevin in Calgary Canada that shows designing and installing solar PV in a small RV trailer.

    Poster Robert "2ManyToyz" has documented many of his smaller solar projects--lots of pictures so you get a good idea of what things look like.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Slappy
    Slappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    #6
    Re: 45 watt system

    those HF 45 watt systems are toys, and you can learn a lot from them. but for real power use, forget it. I own 2 of those kits, for me I have had zero problems out of them, even the controllers.(maybe I am one of the few lucky ones:D) I welded the frame solid, and mounted them over the windows like window awnings.....Well any ways the table top fan alone is going to draw more than those panels will produce. the fan might draw aprox..1 amp at 120v. but it is drawing around 7 amps or so from the battery. and my 6 panels on a good day will put out barely 5 amps. then you have the other stuff that you are running, so your load is a lot greater than your 3 panels(45 watt system). those will be good for small 12volt items to run like the "02 cool fan" and some LEDs that are made for 12v. etc...........as others has mentioned, figure out your loads, and what you would like to run (power), then they can be great help to ya, As I have learned a lot from reading through this forum. and still learning, great people here.
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  • System2
    System2 Posts: 6,290 admin
    #7
    Re: 45 watt system

    So do I need to get rid of the marine battery? Everything I read told us to use that. Hmpf!
    I love the idea of using the panels as an awning!! 2 for 1! Love it!:D
    I was actually able to run that table fan all day, along with watching my portable dvd player at the same time and charge my cell phone. 2 weeks ago I would leave the table fan on for the dogs and it would run all day. Now I get 15 minutes. I dont know, you say in theory that it shouldnt run it then how did it?:grr
    Now I do live in Florida, I know location does make a difference.:confused:
    We got this one as an experiment, and I am learning alot. Where is a good place to buy good quality supplies when I am ready?
    And anyone know of a good, math-idiot proof way of figuring my load? I am horrible at math!!!:cry:
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: 45 watt system

    Nothing is idiot-proof. :p

    As Bill mentioned, for AC loads the Kill-A-Watt is a wonder; just rolls up the Watt hours for you.
    For DC loads you need the clamp-on meter. Amps * Volts * Time = Watt hours.

    You've probably experienced the "putting back a little, taking out a lot" problem. Start with fully charged battery, deplete it 10% daily, recharge it 5% daily. Everything works until the deficit catches up and the battery is now a sulphated mass of scrap metal. Even a marine battery should last longer than that, but won't if not recharged.

    Some of that horrible math is rough, ball park figures:

    45 Watt panel operating at 77% average efficiency (hopefully) = 34 Watts. Times 4 hours of "equivalent good sun" = 136 Watt hours daily. Not accounting for system losses. Over-all with DC to AC conversion you'd expect about 90 - 110 Watt hours daily. Pretty easy to use that up.

    More horrible math (battery recharge rate):
    34 Watts of panel / 14.4 Volts charging = about 2 Amps of current. A typical marine/RV battery is about 100 Amp hours. That's only enough charge current to keep it floating; 2%. Well below the minimum 5% recommended, and even less with loads drawing from it during charging.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,599 admin
    #9
    Re: 45 watt system

    First, get the battery on a regular AC battery charger and get it back full... Either the charger will tell you when the battery is full, and/or learn how to use the DC Volts side of your DMM (battery should be held at 13.8-14.5 volts for 2-10 hours or so--depending on the voltage and size of battery charger).

    Basically, a lead acid battery that sits for days/weeks/months below 75% state of charge will not last very long (months or 1 year or so).

    After that, then you can learn about your existing system--where it works and what its weaknesses are.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Slappy
    Slappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    #10
    Re: 45 watt system
    BGDreamWeaver wrote: »
    I love the idea of using the panels as an awning!! 2 for 1! Love it!:D
    :

    Attachment not found.

    its not much, but it was the only place to put it. have to keep it out of public view, theft has been high the last couple of years. plus I already have enough holes in the roof from the other panels.;)
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  • klrskies
    klrskies Solar Expert Posts: 30 ✭
    #11
    Re: 45 watt system

    I have a similar set-up as you, with a H.F. set of panels and a single 31 series marine battery for storage. I notice the same loss of power you observed after a couple of discharging / recharging sessions...obvious lack of power available after recharging. After reading some of the battery information offered by the helpful members here, and reading how you were advised that you may be under charging your battery, I changed my charging practices.

    I first bulk charged my battery with a 10a automtic charger that takes the voltage up to about 14.5v and then starts going into some kind of cycle but I didn't leave my battery on that charger...I believe my small, 3 panel, 45watt system didn't have enough capacity with the amount of time available in a single day, to re charge my battery which I was discharging way down to about 50~60 % SOC every nite. Bulk charging with the battery charger took that part of the charging cycle off the solar panels and allowed them to fininsh the charging cycle with the capacity they have within the time available. Not suffeciently recharging my battery was likely causing electrolyte stratification and sulfation. After reading thru some of the articles on battery care and maintaince, I decided to bulk charge with my battery charger and then finish the job with my panels and xantrex 35c charge controller ( I didn't try it with the controller provided with the HF system because I don't have the ability to adjust the charge voltage rates on that controller...it may work too). I wanted to finish bulk charging and absorbtion charge at 14.8v at the battery to be sure I was stirring the electrolyte sufficently and breaking up the sulfate crystals.
    After the first charging session the battery was signifigantly better. I let it pull a .75a load for 12 hrs. and used about 20% of my capacity. before I changed my charging practices, I would pull my battery down to about to about 50% SOC with same load over the same time.

    I'll continue to charge like this a few times to try and get my battery back to normal, or as good as it can do after I mis-treated it for a few weeks. Then I'll try to not use more power than I can put back in a day with my panels and see how it does on just the panels. If I'm doing something wrong, or mis-stating something, someone please straighten me out. Thanks for the help & knowledge provided here!

    regards,
    Ken
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