Grape Solar 100W Solar panel for 12V systems - good for backup power?

Discussion in 'General Announcements' started by KN4IOT, May 8, 2018.

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  1. KN4IOT

    KN4IOT Ham Member QRZ Page

    I noticed this morning that this solar panel is on sale currently for $89 USD, and it looks like it's probably about the right power to either help charge up a car battery to run a rig or maybe use it power a rig? I won't get it, because I'm not yet to the point where it would make sense, but mostly curious about what would be a good idea when it comes to having solar power for backup. Here it is:

    Grape Solar 100-Watt Polycrystalline Solar Panel for RV's, Boats and 12-Volt Systems:
  2. KF5LJW

    KF5LJW Ham Member QRZ Page

    Honestly it does not have a lot of use for Ham Radio. It is capable of only charging a relatively small 12 volt battery of 50 to 60 AH. A battery that size cannot handle much power and limited to 10 to 12 amps maximum draw for short periods of time. That would equate to about 50 watt transceiver.

    Solar has another nasty surprise or two waiting for you. Most likely you will buy the cheapest PWM charge controller money can buy, and any PWM charger make your 100 watt a 60 watt panel further limiting power. But that is not the big surprise. Nearly all but a few higher end controllers generate a lot of RFI both radiated and conducted that can render your receiver useless. One of the few that I know can work is a Morningstar SunSaver MPPT 15-amp controller. Being MPPT means if you input 100 watts, you get 100 watts output to the battery. Maximum input with a 12 volt battery is 200 watts, and 400 watts @ 24 volt battery. But like any good MPPT is pricey @ $200 for the SunSaver. Another really good Controller is a Midnite Solar Kid a 30-amp MPPT but those will set you back $400. I have installed roughly 300 remote telemetry and Cellular Radio off-grid battery systems system for pipelines and Cellular Telephone and would only use Morningstar and Midnite solar because they are the only two out there that do not generate much noise and both are excellent quality. The only other controller manufacture I know of that works good with radio equipment you might consider is Genasun. Genasun makes charge controllers for the Marine industry so they are hardened for that environment. I do not use them because all their controllers are small. I mostly use 60 and 80 amp controllers up to 5000 watt input @ 48 volt battery. So a 10 amp controllers just do not meet my application needs, but would be a nice natch for a 100 watt panel.

    Now if you want one to keep a battery charged up say on a boat or RV while in storage, it will work just fine with a plain ole PWM Controller. But if your intention is to operate a station is a really poor choice. Do what any professional does and easy for a ham radio operator to copy. Add a nice size battery like a pair of golf cart batteries to your station DC Power Supply using appropriate fuses and possible a Diode to isolate the batteries from the DC Supply. Set your DC power supply to the correct Float Voltage that ranges from 13.6 to 13.8 and leave the power supply on. When and if power fails you can operate for a few days on a 100 watt Transceiver no problem at all. When power is restored, the battery charges back up and Floats. In addition if you do any field work like a weekend Contest, you are ready to go, just take your batteries and scream Contest Contest until you turn blue in the face.
    US7IGN likes this.

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