Author Topic: Measuring insolation  (Read 2462 times)

zoneblue

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Measuring insolation
« on: October 18, 2013, 06:20:39 PM »
Summarising what has been said to date:

-  to be able to monitor as a datapoint the real world actual maximum harvestable solar energy at any time of the day.
- to help with opportunity load implementations.
- to help guide "is it working correctly" and system expansion decisions
- anything else?

The most promising technique to my eye is the reference panel approach (additional panel on same plane as array). This avoids ALL of the conversion from global horizontal irradiance (GHI) that is produce by various light sensors. Its cheap. and only takes up one channel on our adc board.

The trial panel i ordered was this 12v 80mA one:

http://dx.com/p/solar-power-panel-166-65mm-12v-80ma-17439

$15, mono crysttalline, with glass cover, as near as i could find to what we use. I suspect that the main factor will be in the glass surfacing. Glass reflection is a significant issue past 40% angle of incidence (AOI), see:

http://pvpmc.org/modeling-steps/shading-soiling-and-reflection-losses/incident-angle-reflection-losses/physical-model-of-iam/

12 volts gives us a bit of voltage to play with rather thatn fussing with say a single 0.6V cell. Load resistor, straight into webcontrol?

On pondering lightning risk for the outdoor sensors, Distance, hassle of cable laying, will always be a factor... I guess we have options:

-cable, plus lightning protection
-radio

Zigbee et al is really cheap, reportedly quick and easy to work with. Wifi maybe? http://learn.adafruit.com/wifi-weather-station-arduino-cc3000

Maybe we ought to be thinking a little bigger there:

One outdoor sensor box comprising:
- outdoor ambient temp
- back of panel temp(s)
- reference panel output
- a couple spare ports for site specific optional sensors.
- weatherproof box to put it in, at the array.

Just a thought...  itd be good to get stephenv involved, hes done some of this.
« Last Edit: October 18, 2013, 07:32:05 PM by zoneblue »
6x300W CSUN, ground mount, CL150Lite, 2V/400AhToyo AGM,  Outback VFX3024E, Steca Solarix PL1100
http://www.zoneblue.org/cms/page.php?view=off-grid-solar