DIY 6.5KW Tracking Solar

Steve Sulz

Our Farm

u  46 Acre Farm in Northern Alberta near Athabasca

u  Free run, free range, pasture raised Chickens, Turkeys, Pigs and Goats

u  Honey Bees

u  Self supply all feed

u  Soon to be Registered Organic

u  We are over 80% self sufficient on food

u  Why not self supply power as well????

Why Solar, Why DIY

u  Ultimate goal is net zero power

u  Started with a 1 year test of small scale solar vs wind

u  Off grid 1.5 KW solar and 600W wind turbine, Solar was cheaper per KW-h and produced more power per installed watt

u  Why DIY

u  Each year I try a new project to learn something new and gain new skills

u  DIY installation was significanlty cheaper (free labour)

u  Installed cost of ~$1.90/Watt

u  Very good economics, power is expensive in Alberta

System Design

u  4 Arrays – 6.52KWDC

u  One Array of 16-110W panels (1760W)

u  Three Arrays of 6-265W Bosch panels (4770W)

u  Pole Mounted with two axis tracking

u  Horizontal Primary Axis is manually tracked through the season (North-South)

u  Vertical Secondary Axis is electronically tracked through the day (East-West)

u  Tiny Tracker is used as tracking driver, 24VDC Linear actuator drives east-west tracking.

u  Two Power One 3KW Inverters, two independent MPPT DC input channels, one per Array

Advantages of Tracking

u  Based on testing on my system the average gain is 30.3% with active vertical axis tracking (Based on limited testing, two weeks in May 2014)

u  Higher if you also consider manual horizontal axis tracking, probably ~40%, but I did not test this

u  I would require a 9.1KW fixed angle system to make the same power

u  More space, more panels, bigger inverters, larger power cables

u  Active tracking solar power output follows actual grid loads closely

u  This is good for the grid and allows a higher percentage of grid load from solar

u  Learn lessons from Germany, mid day peak solar output causes major issues for base load grid generation

u  Feed in Tariff or other incentive should favor tracking

Tracker Performance Testing

Tracked vs Fixed

u  Two identical arrays 6x265Watt Bosch panels on each

u  Each array feeding one input channel of identical 3kW Power One Inverters

u  Compared generation for 2 weeks in May, 2014

u  Graph shows results on one “perfect” solar day, May 13th

System Performance- Tracked/Fixed

7600  

7800  

8000  

8200  

8400  

8600  

8800  

9000  

9200  

9400  

-­‐0.2  

0  

0.2  

0.4  

0.6  

0.8  

1  

1.2  

1.4  

1.6  

3:36:00  AM  

6:00:00  AM  

8:24:00  AM  

10:48:00  AM  

1:12:00  PM  

3:36:00  PM  

6:00:00  PM  

8:24:00  PM  

10:48:00  PM  

MW    

PV  kW  

Tracked  vs.  Fixed  Array  May  13th,  2014  Comparison  of  GeneraJon  to  Alberta  Interconnected  Load    

Tracked  Array  (kW)   Fixed  Array  (kW)   Alberta  Load  (MW)  

16.9  kW-­‐h  Tracked  11.0  kW-­‐h  Fixed  

 53%  more  power    

Tracker Design

u  Designed and constructed tracker bearings and array mounts

u  Used 1” tubular steel and 2” angle iron

u  Pole mount made from re-purposed 6” pipe

u  Pole cemented 8 feet into ground to take wind loads

u  Trailer jack modified for North-South seasonal angle adjustment

u  24 volt linear actuator drives east-west daily tracking $120 each on Ebay

u  Built in limit switches

u  1000 lb actuation force, 1250 lb hold force

u  Tiny Tracker used to drive the linear actuator $45 each on Ebay

u  Good tracking accuracy, return to east at night, no “chasing”

Tracker Control

Tracker Frame

Vertical Tilt

Down Sides of Trackers

u  Requires a lot of space for pole mount

u  Not feasible on rooftop

u  Adds complexity, moving parts = maintenance

u  I spent around 2 hours of extra time maintaining the tracker

u  Greasing spring and fall

u  Cleaning tracker bubble, snow & presents from birds

u  Add capital cost, especially when using commercial trackers

u  Higher likelihood of wind and storm damage

u  More visually intrusive installation vs rooftop

u  My neighbors actually like the trackers, but not everyone will

What’s Next?

u  Goal is net zero power in 2015

u  Looking at additional solar and/or wind

u  Considering converting heating to Geothermal to reach net zero thermal