Duel axis tracker foundation

[baz0000]

Always a possibility with trackers over a static frame of fixed panels, we had our first mechanical breakdown after 2 years with one of the East/West actuators giving up hard over to West facing. June is a good month to lose one tracker output (reduced by 75%) as the other tracker was able to take the burden of battery charging before end of daylight and it is not a month known for gale force winds.

Spare actuators (4 total) were ordered from the supplier on 6th June and delivered on 26th June (air freight - FedEx). Cost US$1,100 DDP. No contingency has been set aside for maintenance cost so this outlay will be added to the payback period. This was running at 12.5yrs based on 2 year production before contingency spend, now 13.25yrs after this contingency spend.

Changing the actuator was straightforward using our farm kit. Panels were supported by raised pallet platform on the tines of the telehandler. The new actuator was extended before fitting to ensure the controller was operating correctly. Then the failed unit was lower pivot released and then top mount removed and the new actuator top mounted and extended to align with the bottom mount. The panels were strapped secure to the telehandler while the actuator was being removed and replaced to prevent a possible disaster scenario of wind catching the panels and flipping the orientation onto the telehandler roof. Following calibration of the actuator with a manual full East extend command the controller took over automatic tracking for the first time in 3 weeks.

The failed actuator motor did attempt to move on manual setting so I will strip it down. That the motor tries to turn suggest that the actuator has either experienced a helical gear or hall sensor failure.

[solar pete]

G'day Baz0000,

Thanks for the update on your rather impressive system, have you found your setup is performing as expected ? (besides the odd actuator) and is it covering usage in winter or are you using the grid as back up for winter.

I find my 12kW solar with 16kW/hrs. battery is fine except for winter (in Australia) , you have the catch 22 , if I add more panels and battery its really of a slight benefit in winter where we dont fully charge batterys here anyway. I would have gone a bit bigger on my solar and battery in hindsight but is pretty good to have the grid to use in the winter. Cheers

[baz0000]

After a year and a bit running I did the drill down maths on whether it made sense to increase the battery capacity and/or add more panels to our system. From memory the pay back on panels was going to be 16 years and additional battery capacity was going to be 26 years so neither made any financial sense. I concluded from the sums that the system I set up was the optimal compromise giving us near self sufficiency for 3 months of the year, a great contribution for 6 months or the year and three months with doing not a lot. So extra batteries would never get charged in the Winter and not be required at all in the Summer. Extra panels would add nothing much in Winter and would not be needed in the Summer So either option is only of any practical use for half the year; effectively doubling the pay back period.

The best upgrade I performed on the system earlier this year was to link the inverter to Home Assistant. This enable near real time monitoring of key sensors:

Battery SOC
PV output
Net battery charge or discharge rate
Battery and Inverter temperatures

Being HA integrated on the inverter meant I could change the manual transfer switch for a Smart ATS that is also HA integrated. This allows me to set when the solar switches to mains based upon a low point battery SOC and also when mains switches to solar triggered by a set battery SOC or PV output level. This automated switching between solar and mains has enabled me to leave the house load on solar and sleep through the night knowing if the batteries fall below the set level the system will automatically switch to mains. So, I can now utilise the solar more allowing the batteries to run down knowing I am not going to wake up to an inverter shut down due to low battery SOC. I recon this is going to allow me utilise an additional 500kW of solar power throughout a year (chiefly in Autumn and Spring) over the previous manual switching.

The HA automations I have set for the mains load are:
Mains On #1 - low battery SOC (varies from 25% to 80% depending on Season)
Mains On #2 - Backup battery SOC (A backup level below the #1 as cover should #1 not trigger, ATS offline event etc.)
Solar On PV - A PV output trigger that indicates the sun is shining set to 2.5kWh trip, it is limited to one time a day action to avoid sunny intervals on a otherwise cloudy day
Solar On SOC #1 - This allows me to set when the switch to mains will occur on a recharging battery stack. I range this from 40% to 85% depending on Season
Solar on SOC #2 - Switch to mains when Battery SOC hits 100%

If I didn't have the option to switch to mains then I would instead have an off grid inverter coupled to a generator as backup supply. You can get smart generators or add smart modules to generators so again it would be possible to integrate automations in HA to switch the generator on and off based upon the battery SOC condition or the PV output.

I like my setup as I hit on the optimal cost/output combination out of the box, probably as much luck as judgement. With the added automation I no longer need to constantly monitor the status of power in and to the home. Having 2 tablets set up that display the HA data they give plenty of information that a quick glance tells you all you need to know. On an off grid setup the main concern now (having cracked the Battery SOC anxiety) is preventing inverter overload and colour changing bars help minimise our overload events to occasional incidents.

I'm happy with it and a get to admire the fruits of my labour every time I go into my garden and look over to the orchard where the trackers sit and do their thing. It isn't a money maker or money saver but it keeps the lights on when everyone else's goes out.