Energy Inexpensive US made 320 watt solar panels...

Discussion in 'Off Grid Living' started by techsar, Aug 28, 2016.

  1. techsar

    techsar Monkey+++

    For anyone thinking of starting or expanding their solar system, I have found these panels to do rather well. Output is close to the rated specs and this is on a fixed mount, not ideal alignment, but pretty good. 305 watts/panel on a partly cloudy day...
    Frame is good, large enough to allow for various mounting systems including DIY. Out of the panels I received one had a small blem on the backside, but nothing that would cause issues with performance or weather-resistance.
    The only negative thing is the shipping. If you're only going for a panel or two, you may want to check for something more local, but for larger orders the per-panel rate comes down. They do contact you prior to shipping to verify shipping costs and to confirm you are ok with the amount.
    Disclaimer: I do not work for, nor am associated with this company other than being a (satisfied) customer.
    ETA: At this time, they are $109 USD per panel (plus shipping)


    UPDATE - this company is no longer in business....12/29/2019 :(
    Last edited: Dec 29, 2019
  2. SB21

    SB21 Monkey+++

    I'm not real experienced in electrical work . How do I figure my power usage to calculate the size of panels I would need , wattage size . Say for instance , how long would , or could a 305 watt panel run a normal sized refrigerator ? TV ?
    Motomom34 likes this.
  3. Asia-Off-Grid

    Asia-Off-Grid RIP 11-8-2018

    "How long" is relative. The number of, wattage and age of each panel, as well as the quality and type of your batteries, and the reserve battery capacity you have, are all determining factors.

    First, determine which loads are "necessary", and which are not. What do you absolutely need powered off solar? (This can save you tons of money, once you are at the point of buying / building your system.)

    Then, I would suggest buying a power meter. A popular brand is a "Kill-A-Watt" meter, as an example. Plug each (necessary) appliance into this for 24 hours. This will let you know your average power requirements for a given appliance. (The reason for this is, although power ratings are listed on most all appliances, they may not be exactly accurate.) Obviously, if you do not have power at the location where the appliances are, you will have to go by the rating labels on each appliance.

    The formula for determining total power usage for a given appliance is: watts x hours of use = watt hours per day. So, an appliance that draws 60 watts is needed to run for 7 hours per day. 60 x 7 = 420 watt hours, the appliance will use within a 24 hours period.

    Another formula is to determine your amp hours needed. So, watt hours per day / system voltage = amp hours per day. Figure, all your appliances added up, using the previous formula, come to 2,000 watt hours per day. This is the same as 2kWh. So, 2,000 / 24 vdc = 83.3 AH is what you need to run all of your needs over a 24 hours period.

    Now, get to the batteries. On deep cycle / solar batteries, you do not want to discharge them more than 50% - ever. Well, not current lead acid batteries, anyway. This is called the DOD, or Depth of Discharge. So, you would want to at least double that, making it at least 166 AH, if not more. (I will explain this in a bit. But, first, the reason for 24 volts, over 12 volts.)

    The higher the voltage you go with your system, the lower the amperes, thus the smaller the wires necessary, to power your system. Higher voltage = lower ampere draw and lower line losses. Lower voltage = higher ampere draw, and higher losses in the line. Anything over about 1,000 to 1,500 watts systems, I would suggest going with 24 volts. Anything over say 3,000 to 3,500 watts, I would suggest going to 48 volts for your system.

    Now, back to the amp hours needed, DOD, and days of autonomy. What I meant by "if not more", above, was you need to take in account x number of days without sun - snow or rain storms, or even cloudy days that would affect the output your panel array could generate. To figure this, you would simply take your daily needs and multiply them by the number of days of autonomy you need. (Three days is a common length of time.)

    Let's stick with the current example I started, above. 166 amp hours per day, allowing half of that for your actual needs. Let's multiply that times 3. So, 166 x 3 = 498 is the number. Let's call it 500 amp hours of batteries, at 24vdc. So, 500 amp hours should cover your 83 amp hour daily power requirements for three days - with no sun.

    Okay. Once you have calculated how many amp hours of batteries you need, you can then calculate the number (wattage) of panels you will need to charge your battery bank. Personally, I like at least a 10% charge rate. But, I have seen rates as low as 4% to 5% on systems. That is too slow for me, especially after a couple of days of bad weather. To calculate what you need in the way of panels, and including efficiency of said panels, this is a pretty good formula:

    500 amp hours x 29 vdc charge voltage / .77 array efficiency x .10 charge rate = 1,883 watts array.

    Call it 2 kilowatts of panels.
  4. SB21

    SB21 Monkey+++

    Thanks for that info . I will be making a trip to the local lowes store today to find that kill-a-watt gizmo . So if I take my monthly power bill and use that for my total consumption rate I can figure this out . Stand by , I'm sure there are more questions to come .
    inthewoods and Asia-Off-Grid like this.
  5. techsar

    techsar Monkey+++

    Do yourself and your wallet a huge favor...before investing in solar, do whatever you can to become more energy efficient. Not needing energy is infinitely cheaper than producing power.
    Energy efficient appliances, led lighting, disconnecting units with "instant on" such as tv, dvd, satellite box...these will all save you money whether or not you go solar/wind/hydro. Then decide what you NEED to power, and for how long.
    While working on conservation, look at your location carefully. Is there a place you can put panels?
    Is it shaded at all? Does it allow exposure toward the sun (generally southward)?
  6. SB21

    SB21 Monkey+++

    This is good info , I live in a kind of a small valley , tall trees , so the solar thing , altho interested in it , but not sure it will be effective where I'm located now . My power bill isn't high at all , until I put in this inefficient ac unit in this year . But would still like to start practicing with this a little in case my dream of being able to get to the hills happens . Also , this will help me figure out what I can run in a power down situation on batteries . I've got it now where , when I leave the house now , I could kill all the power to the house except the fridge . I downsized to a 12 gallon water heater , and put it on a switch , so when I need a shower , I flip it on and 15 to 20 minutes later I'm good to go . Figure thats better than heating water all the time , when not needed .
    GOG and techsar like this.
  7. oil pan 4

    oil pan 4 Monkey+++

    Only while the sun is up.

    If you have an electric water heater there really isn't any reason to down size.
    Electric water heaters are the most efficient at storing heated water. They are recommended for homes where its only 1 or 2 people.
    If you turn the water heater off and after several hours its not warm enough to take a shower with then it sounds like it is seriously lacking some insulation. If the water heater is well insulated turning it off really shouldn't be saving any power.

    Lose the cheap inefficient air conditioner. I just put in a high efficiency split type inverter heat pump. It cost almost twice as much as a cheap A/C but I figure the pay back will be 2 years or less using the air conditioning only. Using heat pump for heat pay back will be even faster. The high efficiency cools the bed room and draws less than 2 amps of 240 volt power and it has no start up surge so it will work well with solar inverters or a generator.
    The cheaper A/C only split air conditioners cost around $600, the high efficiency heat pump was $1,000. Absolutely no buyer remorse. I installed it my self so there was no installation charges.
  8. Asia-Off-Grid

    Asia-Off-Grid RIP 11-8-2018

    One thing I failed to mention, but wanted to was this. IF you are on a mains connection where you live, going to off-grid solar for your power requirements will NOT be a cheaper option. Unfortunately, and all too often, people believe it is. Off-grid solar arrays are best used for areas where mains power is NOT available, or where the power company wants to charge you something like $150,000 USD to run service to your property. Otherwise, off-grid solar is quite costly, per kWh generated.

    If you live in an area where you have mains power existing, I would strongly urge you to consider going with a grid-tied, or maybe even a hybrid system (which would still use batteries), for your system. Most likely, you would be able to sell power back to the grid, using either of those options instead. Check for your particular area (in the states?) to see what tax incentives may be offered for going with a grid-tied system for your home.
  9. AD1

    AD1 Monkey+++

    sec_monkey, 3M-TA3 and SB21 like this.
  10. AD1

    AD1 Monkey+++

    The shipping on these is NUTS but at 55 lbs and 76x40 inches they are big.

    3M-TA3 likes this.
  11. arleigh

    arleigh Goophy monkey

    Thanks for the info ,
    I can get used ones here for about the same price and actually have all that I need at the moment, BUT I am looking toward investing in spares for the future, as they don't age if there not in the sun, and even in service last decades .
    I have some over 30-40 years old still contributing.
    I believe that it is a better reference to say that I am on a "battery system", using wind and solar,and the grid to supplement the energy.
    Batteries can be charged by many different means but having the battery bank gives e more reliable power than the grid and I don't have to worry about bowls or spikes or black outs ruining my equipment. And that is a savings no one else seems to think of.
    My house is wired 6-12 volt DC and 110 and 220 AC and most of my lights are 6-12 volt LED and a few AC - LED .
    My bank consist of 6 volt deep cycle golf cart batteries.
    Every single component is wired to a 3 position switch and meters, so that at any point I can check any component to see how it's is functioning.
    Asia-Off-Grid likes this.
  12. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Where did your panels ship from ?
    My last container was out of corrona CA.
    Pallet sizing 20 per ? double stack = 40 per lift for 350 is cheap
  13. techsar

    techsar Monkey+++

    Although the company is in Norco, CA, the panels shipped out of Tennessee. It seems a pallet consists of 20 panels...over 20 you have to contact them for rates.
  14. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Last order was Canadian Solar & 24 per box/pallet in double stack =48 per forklift truck, 12 double stack lifts per 40' container . Best way to ship & buy is what I found.
  15. T. Riley

    T. Riley Monkey+++

    It seems to me 10 panels would be $1,395 delivered for 3,200 watts. That's way less than I have ever paid. Am I missing something?
  16. Asia-Off-Grid

    Asia-Off-Grid RIP 11-8-2018

    When did you last purchase panels? Prices have even been dropping here in SEA, sharply.

  17. techsar

    techsar Monkey+++

    Missing the boat, perhaps ;)
    Your math is correct, and as Asia-off-Grid mentioned panels have been dropping in price for a while now. Heck, if you really want a shock, frameless 320 watt panels are $89 + shipping. Mounting system is going to offset the savings unless you have a good source.
    Cruisin Sloth likes this.
  18. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Also the market is flooded & the sales are in lagging . Not in your real NEWS . Many deals can be had.
    Yard Dart, Tevin and techsar like this.
  19. Tevin

    Tevin Monkey+++

    $250 for a 320 watt panel is not a super-awesome deal; its kind of average. You can get similar prices almost anywhere. They will stick you on the shipping because the large panels are freight/oversize packages.

    I run a lot of solar and do not have any panels (at least none that I bought new) larger than 140 watts because that's the biggest panel that can be shipped standard UPS/FedEx ground.

    Other than up-front installation, there is no meaningful technical advantage to one large panel vs. two or more smaller ones. The price per watt goes down as the panels get larger, and as we can see, that savings is more than wiped out in shipping fees.
    SB21 likes this.
  20. oil pan 4

    oil pan 4 Monkey+++

    Yeah 300+ watt panels are pretty big.
    A panel that is over 6 feet tall and almost 4 feet wide and weighs 55lb isn't going in the back of a UPS truck unless you only order 1.
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