February 2025 update

 Over a year ago, a lightning strike destroyed or damaged most of my solar power station.

Only the panels were spared. The lignbting came into the house over the aircraft cable guy wire carrying signl and power cables from the panel array.

I replaced the Epever Tracer 3210 charge controller with an Epever Triron 4210.

I replaced the inverter with a 

My lead-acid batteries had a much shorter lifetime or were destroyed. The battery bank went throough a major upgrade. LiFePO4 batteries had become affordable, and were, therefore replacements for the Duracell Ultra Marine lead-acid batteries. 

I also chose to, at this time, upgrade and update my Raspberry Pi and associated software, always a formidable task.

I updated the RPi3b with a RPi4b-2Gb. The prevoius operating system, Debian Buster, was replaced by Bookworm 12. 

PHP and Python programs were both updated to current versions as well.

The Exar driver, always a pain and always taking days, was a pain and took days. However, the programmer of the original driver software, Kasbert on github, provided software to send and receive messages from the Exar driver, now an integral part of Raspberry Pi OS, labeled as 'xr_serial.'

I needed software that would work get the driver running but without any interaction. That work-around lasted for a week or two. I tried everything to use the code, but the minimal use resulted in two failed tries before USB0 would run consistently. 

I tracked down the linux source code and discovered some code in an article on serial rs485  communications. I extracted the code and made minor modifications to get a runnable executable.

I compiled the code in the Raspberry Pi and that solved the Exar driver problem.

Currently, everything is up and running. My next taskk is to change the online graph software. 

I have been using HTML, PHP and D3. The new software is Dynagraph 2.2.1. That software seems so much easier than D3. And more versatile too.

The queue also includes a new array suport system made from 'superstrut.' The old patched aluminum ladder plus 2x6 and 2x12 is gone, as is the large concrete slab used as an anchor for the ladder and array.

February 28, 2025.

RPi update & battery calculations

 The RPi is online and running 24/7 now, but not collecting data or moving the array. 

I decided to bite the bulket and update to Bookworm OS and python's virtual environments.

I still haven't gotten the network set up the way I want and the OS included Exar driver is not working, and while the Maxlinear driver compiles, it is not inserting ('insmod').

More study is needed.

I still need two more batteries.

Battery charge time calculations.

I have 585 watts of solar panels that I will round off to 600w.

I also have 4.2kW of battery storage.

4.2kW/0.6kW=7hr to full charge

But, the charge controller has a ma charge rate of 20A for the configuration.

20A x 12V = 240W=0.24kW

 This results in a charge time of 

4.2kW / 0.24kW = 17.5hrs to full charge from complete discharge.

A complete discharge is not likely since system shutoff is set at 10.5V.

Four batteries

 I now have four LiFePO4 batteries in place and balanced. The batteries store 4.8 kWhr of energy. 

The RPi is now set up and running a 24-hour schedule.

New Batteries: Three and counting

 There are now three LiFePO4 batteries wired in parallel, connected to my system.

   There is a fourth on order.

   Eventually, I want to have six for a total of 7.2kWh of stored electrical energy. 

   The catch is, there is a high probability tariffs wiil be levied against Chinese products by the incoming President. Prices will go up. There's no way to know how high prices will go and if availability remains steady.

   For that reason, I'm considering buying the remaing two before next year (2025). Another, more positive incentive, is a 30 day price guarantee for $147.16 per 12V/100Ah battery.

Currently, the retail is $169.99. I will have to think about this some. The guarantee ends on the 23rd, I believe. I'll have to tighten my belt, if I do.

New batteries

 Ever since the lightning strike of last year, I've been recovering, slowly, but surely.

A few weeks ago, the first of several LiFePO4 batteries arrived. The old lead-acid battreries were relatively short-lived and probably suffered damage when lightning ran in on the steel guy wire.

Use of the type battery has taken some getting used to, but I'm finally settling in and ready for the next two or three.

The lithium-iron-phos[phate battery can be dischrged completely and recharge in as little as three hours. Lead-acid batteries should not be discharged below 50% and are slow to recharge. Think days in the winter time. I had six Duracell Ultra Marine lead-acid batteries.

The old batteries were sold and the money placed toward the purchase of the first LiFePO4 lithium iron phosphate battery. The new batteries cannot start a car, but they last longer, charge quicker, and now are much cheaper, and they can run a lead-acid charger to charge an auto battery. The new battery cost about the same as a lead-acid battery with core charge. The new batteries are 12VDC@100Ahr where the lead-acid batteries were 12VDC@50Ah. I will have the same capacity in three lithium batteries as I had in six lead batteries. Note : I am moving quickly now since the incoming president has stated tariffs of 30% will be placed on imports, especially, Chinese, where the inexpensive batteries come from.

There is a need to understand the new battery type, for their are settings associated with the type that differ from those of the old lead-acid type. I corresponded with three sellers regarding the settings. 

Epever - for the Triron charge controller.

LiTime - for the new LiFePO4 battery

WattCycle - for the two LiFePO4 batteries on their way.

I also consulted several YouTube videos on the best battery brands and the settings.

I am confidant the setup is pretty much optimized. The next step is to re-build the panel array and supporting framework. The ladder support toppled due, I believe, to a high wind one night. The array needs an improved support, one that is stable in high winds. The panels need to be replaced by higher wattage panels. This may, in turn, require modification of the inverter-controller setup.

Solar power station Limitations

Charge controllers:

Epever Triron 4210N / 40A@24VDC

Xantrex C-60 PWM / 60A@24VDC

Inverters:

Xantrex Freedom X 1200 / 1200W

Batteries:

12V/100Ah / 1200Wh

Panels:

5x100W+1x85W / 585W

Upgrades needed for 2kW station:

Approx. 2400W

2400/24v=100A

The source for panels will probably be used panels from 'SanTan Solar' with a branch in Atlanta.

Changes done

The changes mentioned in the last post have been completed. 

In addition, two three-to-one solar cable splitters have been replaced.

The new relay card will arrive mid-November.

I'm looking for software scripts to SSH into the RPi and program the Triron. I found some but the Boost Duration and Equalize Duration registers cannot be read or written to correctly.

UPDATE:

The relay card has arrived.

The LiTime LiFePO4 12V/100Ah battery has replaced the 12V lead-acid battery. More on the lithium battery, later.

Mechanical and Electrical update with possible future software updates

Two basic mechanical changes will have been made:

1. replacing the temporary round aluminum tube with Superstru half channel.

2. lift the array several feet off the ground.

Two electrical changes:

1. replacing the existing, underrated card with a more suitable card.

2. The duracel batteries are being replaced by LiTime 12V/100Ah LiFePO4 batteries. Communications over a couple of weeks with agents of LiTime and Epever plus extensive online searches, has resulted in a usable set of parameters for the Triron-LiTime pairing.

Future software change: The Dygraph software may replaqce the existing hml graph.

 The array framework has long needed some modifications. Some of the originlal work was haphazard and only temporary in intent. Yesterday and today and tommorrow will have been spent making the needed changes. The array is also being raised higher off the ground. There have problems with the lawn grass wilting under the lower end of the array. The new arrangement will leave the bottom of the array several feet off the ground. A five foot section of pipe was attached to the existing pipe using a junction/coupler. The most needed change is the replacement of temporary round aluminum tubing as a base for one of the panels. Superstrut half channel is the replacement and matches the rest of the framework.

The wench used to raise the array onto the pipe, originally, is being used to lift the array several more feet. The wench had to liberally oiled to overcome friction. The pipe clamps on the pipe were also oiled to make the lift easier. One additional benefit of the lift is the full west facing tilt available to catch late afternoon sun.

A new relay card is on the way. The recent card worked when underated. That was good luck. The replacement did not last so long.  The reason turned out to be the ratings of the relays used. The ads stated 12V, 24V which I assumed was the working load voltage. I was wrong. The relays are marked 14V, which is why they failed with a 24V/13A load.