brand new to solar

Hi Guys, I'm absolutely brand new to solar save for the experience of wading through the internet for the past four hours. This afternoon I got two kyocera panels - 120w and 80w for $200 bucks at a garage sale. He threw in an old 12v charge controller too. I through the panels on the porch roof wired it up with 10gauge outdoor wire. I pulled the 1000w xantrex inverter and battery out of my boat and now I have a little system to run my x-mas lights.

In researching how to set this stuff I quickly realized how expensive this stuff is. Man!!! Anyway, what can I do with these panels after xmas. My wife is talking about wanting to have solar powered room. How do I go about this with out spending much more money? What about batteries? Is kyocera a decent brand and if I buy more panels do I need to stick to that brand? What sites I should I visit for more info? Seems the wife wants to get into solar but since we're fairly cash poor we need to do this gradually but I'm compelled to do it right from the beginning. Can you guys get me on the right track to build a modular system? BTW- I live in Phoenix so sun light is not an issue.

Thanks.

Comments

  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: brand new to solar

    it sounds like you already have a system. all you need do is mount the pvs and run the appropriate sized wires to the batteries from the pvs and the inverter. you may want to monitor the voltage as an indicator of the batteries charge condition so that you don't drain them beyond 50% depth of discharge as that would ruin the life of the batteries. beyond that just make sure the loads you draw aren't excessive for your system and allow for regular utility power to be used as backup when you have to many cloudy days or you used too much power from your batteries so that your batteries will be allowed to recharge. knowing you have 2 different sized panels you could not put them in series even with another controller(which you did not mention the one you got from him). expansion of the system may involve another controller as well as more pvs. do try to use fuses to protect from accidents happening and you may want a dc switch in your system(is optional) to isolate the solar from the batteries.
    kyocera makes good pvs, but they did have a bad batch of 120w pvs back in 2001 i believe. when adding more pvs i'd try to keep the voltage close to the original pvs like within +/-.2v, but even this isn't written in stone. losses just go higher when differentials are larger, but do not go to pvs that are for higher voltage systems like 24v when yours is 12v. even going 1v higher you don't want to do just for clarity here, but very high voltage differences will have high losses or destroy your stuff or both. i'm rambling here and i don't want to confuse you so i'll stop at this point.
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: brand new to solar

    Jazzharper,

    Let’s start with this question:
    Anyway, what can I do with these panels after xmas.

    Your two PV modules can be wired in parallel to create a PV array rated at 200 W (STC). As a practical matter, they’ll probably be good for ~168 W around mid-day.

    Your mid-day charge current into a 12 V battery will be ~168 W / 14.4 V = ~11.5 A. A battery (or a battery bank) with a 20 hour rating of between ~105 Ah and 250 Ah would be a good match. 105 Ah is typical for a Group 27 size 12 V deep-cycle battery. Two of these wired in parallel would be rated at 12 V x ~210 Ah (a bit more actually, but that's another story). See more on recommended battery size below.

    Flooded-cell lead-acid batteries are very dangerous. They contain sulfuric acid, they must be maintained (electrolyte levels checked, water added, etc.) and they must be vented to the outside when being charged. Children, pets and uniformed adults must be protected from the batteries, and the batteries must be protected from children, pets and uninformed adults.

    Read, learn and observe all applicable safety practices. Here's a good place to start: http://www.trojanbattery.com/Tech-Support/BatteryMaintenance.aspx

    Average daily insolation on south-facing panels tilted up at latitude (~33 degrees) in Phoenix in January is 5.1 hours. 168 W x 5.1 hours indicated that your system can produce a daily average of 857 Wh, or 0.857 kWh.

    Flooded-cell lead acid battery efficiency (W out / W in) is ~80%, low-power inverter efficiency might be 85%, and overall wiring efficiency might be 97%. So, the net average daily energy available in January will be 857 Wh x 80% x 85% x 97% = 565 Wh.

    What you can do with 565 Wh / day depends upon your loads. You might want to buy a Kill-a-Watt meter to measure your loads’ power requirements. For example, if your laptop draws 85 W, you could run it for 565 Wh / 85 W = ~6-2/3 hours per day. Or, you could go to Home Depot, buy a six-pack of 14 W mini-spiral compact fluorescent lamps for ~$10, and you could run five of ‘em  at night for 565 Wh / (5 x 14 W) = ~8 hours.

    Back to the batteries. As niel indicated, it’s not good practice to regularly discharge a battery below 50% state of charge. You also want to be prepared for other than sunny weather. So, allowing for three days in a row of bad weather and not discharging the batteries below a 50% SOC, you need a battery rated at six times the average daily energy requirement.

    Including the inverter’s conversion loss, the daily energy requirement from the battery will be 565 Wh / 85% = 665 Wh. 6 x 665 Wh = 3,990 Wh, or a 12 V battery rated at ~332 Ah. That’s larger than the 250 Ah maximum battery size suggested above, so you may have to reduce net energy use to ~425 Wh/day during bad winter weather periods of several days.

    How’s this for a start?

    HTH,
    Jim / crewzer
  • System2
    System2 Posts: 6,290 admin
    Re: brand new to solar

    I forgot the mention the panels were wired together when I got them. I don't know if they are wired in series or parallel and honestly I can't tell the difference.  There was only one wire coming out of the panels that I could connect to. I don't know if they are 12v or 24v. I know the charge controller is 12v and I didn't put much thought into it... I assumed what he gave me would work as he said all you need is a battery and interver and then you can run your xmas lights, so that's what I did. The panels I got we made in 2005. 
    My wife wants to have an emergency back up energy source, there have been a black outs during the summer that have last more than a day.  She wants something that can run a fan, laptop, small TV/DVD player and a light or two in the event that happens.  Sitting around in the dark is pretty boring!!

    Do I have enough to do this?  I know I will need a new inverter and battery(s) because what I am using at the moment is for the boat. I'll check out the trojan batteries.  Anyone know of local phoenix dealers, I'd love to buy directly from the host company but flag is quite the drive just to buy some batteries... then again we're do for a day long rooad trip so it's possible.

    The other thing about my house. I don't have a portion of the roof that faces south.  I have east and I have west. I have a flat roof that cover the back patio and another flat roof that covers the front porch.

    I'm getting a kill-o-meter asap

    You guys are great. Thanks for you patience with me.
  • SolarJohn
    SolarJohn Solar Expert Posts: 202 ✭✭
    Re: brand new to solar

    Jazz,
    My wife wants to have an emergency back up energy source, there have been a black outs during the summer that have last more than a day.  She wants something that can run a fan, laptop, small TV/DVD player and a light or two in the event that happens.

    I was able to use my small PV system to run a corn-burning stove during a recent power outage.  While some of my neighbors had to move out due to the extreme cold, I had heat.  I learned a lot from that experience. 

    We also had extended power outages during the summer months, and I was able to use my system for lighting, fans, TV, etc.  This would more closely resemble the way you would use your system, since extreme cold is not a problem in Arizona.

    I soon realized that the most worthwhile upgrade would be to replace my modified sinewave inverter with a true sine wave type.  Having done that, I can now power a TV without annoying streaks, I no longer get a buzzing sound when I listen to the radio, and motors run at the correct speed.  I no longer worry that sensitive electronic equipment will be damaged by the cheap msw inverter. 

    After I add more panels and batteries, I'll probably use my system to keep a small chest freezer running.  However this is a trade-off.  If I use power for the freezer, at any given time I'll have less stored power available for emergencies.  Just my thoughts.

    John
  • System2
    System2 Posts: 6,290 admin
    Re: brand new to solar

    that inverter I pulled out of my boat powers up my 27" TV just fine. No lines and no issues. Before I hooked up everything to my xmas lights I was putting most of it together in the house and used the TV for testing. I don't remember were I got the inverter maybe Fry's but I know it wasn't too expensive.
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: brand new to solar

    Jazzharper,

    I suspect your two PV modules are wired in parallel. You can check for this by examining the wiring. If the modules are wired (+) to (+) with one wire and (-) to (-) with another, then they’re wired in parallel.
    My wife wants to have an emergency back up energy source, there have been a black outs during the summer that have last more than a day. She wants something that can run a fan, laptop, small TV/DVD player and a light or two in the event that happens. Sitting around in the dark is pretty boring!!

    This statement, in my view, is a practical example of the right place to start in designing and specifying your solar energy system: Establish (and minimize) the energy requirements.

    Using the Kill-a-Watt meter, you can get an idea of how much power (Watts) each devices uses. Multiplying the power times the running time will establish that device's energy requirement. Adding up the individual energy requirements will give you a good idea of your total daily requirement.

    For example, if the fan draws 100 W and runs for four hours/day, it’ll need 400 Wh/day. If the laptop draws 85 W and runs for six hours/day, it’ll need 510 Wh/day. If two lights each draw 15 W and both run for three hours/day, that’ll be 90 Wh/day. The total would be 1,000 Wh/day, or 1 kWh/day.

    Assuming your new inverter (true sine wave strongly recommended) is 90% efficient, those loads will pull 1,111 Wh/day from your batteries. Returning to my earlier post, you’ll need a 12 V battery bank rated at 1,111 W/day x 3 days / 12 V x 50% SOC = ~555 Ah.

    Allowing for 80% flooded-cell battery efficiency, your system will need to harvest 1,111 Wh/day / 80% = 1,389 Wh/day. Assuming 85% effective operating efficiency and 97% overall wiring efficiency, your array will have to collect 1,684 Wh/day.

    Using insolation of 5.1 hours/day (worst case average, January), the PV array will have to be rated at 1,684 Wh/day / 5.1 hours/day = 330 W STC.

    Short cut: For every 1,000 Wh/day of energy need, you’ll need 330 W (STC) of PV array.

    You don’t need to go to Flagstaff for batteries. Talk to NAWS and see if they can point you to a local supplier. Also, you may want to consider AGM batteries. They cost more than regular flooded-cell batteries, but they’re sealed, they require little maintenance, and they’re ~90% efficient.

    Translation: Using AGM batteries, a 295 W (STC) array (smaller and cheaper than 330 W) will get you to 1,000 Wh/day.

    Can you mount and tilt up a south-facing PV array on one of the patio/porch covers? Also, make sure that the PV modules are in "clear" Sun from at least 9 AM to 3 PM -- shading is a no-no!

    HTH,
    Jim / crewzer