Solar Panels....

Discussion in 'Ham Radio Discussions' started by KB4MNG, Jun 23, 2019.

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  1. KF5LJW

    KF5LJW Ham Member QRZ Page

    There you go a match made in heaven when paired with a 140 watt or more panel. Having said that 140 watts would be the lowest wattage I would use. What I am driving at is the Controller limits current if over driven bay say a 170 watt panel. It just Clips off the Power. That can be used to an advantage. It would take at least a 140 watt panel to push 10 amps of charge current into the battery. The amount of time or peak power is Solar Noon and the only time it can produce full power. By over sizing the panel a bit is no problem for a Controller, but what it does is provide more time at full rated capacity. Instead of 15 minutes full Controller Power you get an extra 30 to 60 minutes at maximum controller power.

    So 140 watts is the minimum I would use on the Genasun to take full advantage of it. If it were me I would use a higher voltage thus higher wattage panel. 180 to 200 watt panel, or use 2 of your 100 watt panels wired in series to keep panel current lower. Example with 2 x 12 volt, 100 watt panels wired in series
  2. KF5LJW

    KF5LJW Ham Member QRZ Page

    Your reading comp and history needs work.

    Edison was an idiot compared to Tesla. Tesla worked for Edison, and Edison fired Tesla. In the meantime Westinghouse took Tesla and built the first AC generating plant at Niagara Falls. Edison blinded himself with his light bulb because it required 110 vdc. Edison was hellbent to prove Tesla wrong, and moved to building DC power plants to sell his light bulbs. Edison was wrong on all accounts. Tesla, who Edison fired, got it right.
  3. KF7YED

    KF7YED Ham Member QRZ Page

    So, before the Edison/Tesla argument completely hijacks this thread.....
    Yes, I figured it would just take longer to charge using less-than-ideal specs on the panel. And I get that noon is the peak output time and either side of that is less than spec. So as long as I won't blow up the Genasun or the battery, I'm good to go. Need some 14/2 stranded and connectors and I'll see what works.
    Thanks for all the replies.
  4. KK6NOH

    KK6NOH Ham Member QRZ Page

    Westinghouse didn't build that ac generating plant at niagra falls until after the battle was over. The real killing blow was when Tesla promised to bring electricity to the Chicago World's Fair cheaper than Edison could. The only reason why Edison stuck to DC is because he owned all the patents and wanted to make money, not because he was an idiot and wanted to sell light bulbs. You are correct that Tesla did work for Edison for a time, and was fired.

    Gees, Tesla fanboi much?
    KI3U likes this.
  5. KF5LJW

    KF5LJW Ham Member QRZ Page

    You can easily go up to a 200 watt panel on the Genasun controller with no worries. It will just Clip anything over 140 watts and not go into MPPT Tracking.

    Now 10 amps into a 18 AH battery is not good, and neither is using parallel batteries to get more capacity. So smart move getting a 100 AH battery rather than making the huge mistake of parallel batteries.

    14 AWG may or may not be large enough to keep voltage loss to 3% or less. Certainly more than safe for 10 amps, but if 1-way distance is 10 feet or greater, 14 AWG is not a good choice. To limit voltage loss to 3% or less with 10-amps of load current at 12 vdc your 1-Way wire limits are:

    10-feet @ 14 AWG
    15-feet @ 12 AWG
    30-feet @ 10 AWG

    With this chart you can find what works real fast by using the 3% column.

  6. WZ7U

    WZ7U Ham Member QRZ Page

    10 ga is my go to size for anything of substance, over 10 amps, because I dislike voltage drop very much.

    Yeah, I'm weird.
  7. KB4MNG

    KB4MNG Ham Member QRZ Page

    I saw a documentary stating the problem was that Edison could not understand how ac worked.
  8. KF7YED

    KF7YED Ham Member QRZ Page

    OK. 12 gauge then. Need some spade/fork connectors and powerpoles and wire and it's off to the races.
    And the 18AH batteries were for the radio only. The 100 AH is for the camper only. So it'll end up being two separate systems, then, one panel for the camper/100AH with the Genasun, and one panel for one 18AH/radio battery with the Buddipole PowerMini. I'll swap out the radio batteries if needed. They're two different brands so I didn't want to parallel them for charging. I've heard that's a no-no unless they're balanced.
    So that leaves me with a spare panel. Well, two spare panels. The seller threw in a fourth for free because it measured a couple volts low.
  9. KE8HSF

    KE8HSF Ham Member QRZ Page

    I know you said you do Solar installs professionally, but the above statement is just your opinion. I have the 100W Harbor Freight Solar kit and I used it at this years field day to power my Yaesu FT-991A for digital modes and had no issues. The two marine batteries I have stayed charged showing at least 13.8v the entire time the sun was hitting the panels, never dropped below 12.4v even after the sun went down.

    I fully plan on getting me another set of the Harbor Freight panels to add to the ones i have for next years field day (if I don't decide to go the generator route). They work for me and what my needs are.
  10. KF5LJW

    KF5LJW Ham Member QRZ Page

    OK gonna pick on you for a second, but you should like it in the long run. Couple of points you need to be aware of.

    A 100 watt panel on a 18 AH battery is a bit too much for the battery. Depending if the Controller is PWM or MPPT charge current will be 5 or 8 amps respectively. On a 18 AH battery works out to a C/3.6 to C/2 charge rate. A bit too fast. On a VRLA battery C/4 is about as fast as you want to charge, and on a 18 AH battery C/4 = 18 AH / 4 H = 4.5 Amps. You can get away using a PWM charger as current is limited to panel current of 5 amps maximum. MPPT might cause the battery to heat up with 8 amps of charge current.

    Putting batteries in parallel is a No-No sometimes and not others. Depends on how they are used. Example if the batteries are cycled regularly, then you would be correct and would not want to parallel lead acid batteries. This is one place where BALANCE comes in. No two 12 volt Pb batteries have the same internal resistance, and almost impossible for you to get cable and connector resistance equal. What that will do is over work the strongest battery string in parallel shortening cycle life. If will wear out before the weaker strings, and with parallel batteries you have to replace all batteries when one goes bad. Cannot mix old and new becaaause new will be stronger and wear itself out doing all the work.

    However in a Standby Battery Systems, or say storing battery on charger until needed, you can parallel batteries with some check points to be mindful of. Most important point is all batteries that are in parallel SHALL BE roughly at the same State of Charge aka Voltage within 1/4 volt or less. Example say you have 2 batteries on a charger for a week, month, or whatever you take one out and play radio of go camping. Return home and the battery is deeply discharge down to say 50%. If you were to place it back on the charger with the fully charged battery connected, you will likely draw fire and possible burn wiring up. What would happen is the fully charged battery was in parallel, and as soon as you connect the discharged battery, the other battery on the charger at higher voltage tries to equalize voltage and in doing so sends hundreds of amps into the discharged battery trying to charge it in a second. Not only can it set wires on fire, it can also spew battery acid on FLA, and blow a case apart on VRLA batteries. So to do it correctly requires you to remove the charged battery, get the discharged battery charged up, then you can put the charged battery back on.

    So you can keep you batteries in parallel to keep them charged, then used individually as needed.

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