Small & Portable Solar Electric System

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LBergman
LBergman Solar Expert Posts: 42 ✭
in Off Grid Solar & Battery Systems #1
Just thought I post this small PV system I put together as a general interest thing.

I belong to a local R/C club that has a small field out in the country. Since I fly electric R/C aircraft and the field has no power, this was a problem. Rather than buy a bunch of expensive flight batteries and worry about charging them before I leave the house, I decided to put together a small PV system to power my 12V charger. The photo is the result (sorry about the grainy image).

A 30 watt PV panel supplies power to the 35AHr AGM battery through a 10A charge controller. By standardizing with the same plugs my R/C batteries and aircraft use (Deans connectors), I can use my Watts-Up meter in-line to see how much power the panel is supplying at any one time. I also have a 12v car socket attached to the battery, which a small 75watt 120VAC interverter I have will fit into, thereby giving me 120AV power to charge my transmitter and other flight batteries.

When charging R/C batteries (NiCad, NiMH, LiFe or LiPo) I usually draw in the range of 500ma to 4A. On days when there is decent sun, overall the panel will supply about as much power as I use, basically keeping the battery topped off.

This system has generated quite a bit of interest at my club as several other members are thinking about flying electric. ;) I also get asked a lot about solar panels in general now... :D
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
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    Re: Small & Portable Solar Electric System

    very nice. even though the inverter is adding an inefficient step to the charge process, i'm quite sure it's easier to deal with it than trying to reconfigure everything for the 12v operation.
    all electric planes? i didn't know they had them. maybe you can glue some small cells in series on the wings with a diode and charge direct? added weight too much for it i suppose?
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  • LBergman
    LBergman Solar Expert Posts: 42 ✭
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    Re: Small & Portable Solar Electric System
    niel wrote: »
    very nice. even though the inverter is adding an inefficient step to the charge process, i'm quite sure it's easier to deal with it than trying to reconfigure everything for the 12v operation.
    all electric planes? i didn't know they had them. maybe you can glue some small cells in series on the wings with a diode and charge direct? added weight too much for it i suppose?

    Yep, I just have the supplied 120VAC charger for my transmitter and receiver packs, but I really don't use the inverter that much; usually only when I've forgotten to charge the transmitter and need to give it a boost at the field. :roll: But it's nice to have the option. Can also use it with a small CFL utility light if I stay too long after the sun sets. All my other batteries are charged by the 12VDC charger.

    Most R/C planes sold in the last few years have been electric. You can get them from kits (supplying your own motor, ESC, & batteries) to complete ready-to-fly units. A lot of people (myself included) sometimes convert older gas-powered models to electric. Some of these planes can get pretty powerful, with some of the guys who have a lot of $$$ doing 1/4 or 1/3 scale (90" - 120+" wingspans). Serious electric power there...

    Depending on the plane I'm flying, I use from 8.4v NiCd to 16.5v LiFe packs. Most of them are easily removable, though the harder-to-access ones I just leave in the plane while charging. The LiPol and LiFe types have balancing taps, so each individual cell is monitored separately while charging to make sure no one cell gets over charged (very important for LiPo types). Occasionally, I wonder if such a thing might be useful for the lead acid batteries we use in solar electric systems...

    I've read from various sources that some clubs with the same problem of not having electric service at their fields, installed solar PV systems to meet their needs. I remember an article from two or three years back of one national meet where they needed to supply power for the large number of electric fliers expected, so they set up a temporary solar charging station. If memory serves, they had something like two or four 75watt panels and something like 400AHr of battery capacity.
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