Understanding Solar Energy

The company I work for (as a data engineer) does utility scale solar + battery installation and site management. We recently finished a large scale installation just outside of Las Vegas (by some measures the largest in the US). It was backed by a PE firm. Costs are getting so low, the tech so predictable, and with battery warranties around 20 years the PE firm is able to get pretty high return with a fairly low risk. They enter into a "power purchase agreement" with the utility so they know how much they will be able to sell the power for, and as long as we collect data on the batteries they will be able to be warrantied if there is an issue (but there rarely are issues).

The batteries are by far the most expensive portion of the setup. The solar by comparison is dirt cheap. We have single axis tracking like mentioned in the article. Every day we fully charge the batteries, and discharge them in the evening.

> I work for (as a data engineer) does utility scale solar + battery installation and site management.

Did you build your own excel/python nightmare or is everyone using 3rd party management software for this?

> as long as we collect data on the batteries they will be able to be warrantied

Can you share some of the data? Beyond power in/out, do you monitor humidity, vibrations, temperature ?

Our data pipeline looks like this:

hardware/PLC --modbus--> kepware --mqtt--> mosquito broker --mqtt--> mqtt2prometheustool --http--> Victoria Metrics

The mqtt2prometheustool is something we developed in house. I am looking at removing one or more of the above steps and using telegraf instead, as it can ingest OPCUA or modbus data directly.

We use excel files just as the output of our reporting tools. For analysis it's the standard python data science stack of pands/numpy/scipy. Most people work in Jupyter notebooks, and their tools are eventually moved to services in our k8s cluster.

Temp and voltage are the main "cell level" datapoints we collect. I don't think we have any vibration sensors at site now.

Does this include thermals on batteries? And how much power is spent on keeping them at the optimals? What about SoC/SoD figures?

Because without that the 20 year promise is bullshit.

I can sort of name ballpark figures for the above, the thing I can't get is how this can even approach profitable w/o hype and subsidies.

> Does this include thermals on batteries?

Yes, not just batteries, but we collect cell level temperature for all cells in all batteries.

> And how much power is spent on keeping them at the optimals?

We run an AC unit on every container to keep them cool. (Its in the NV desert so never any need for a heater)

> What about SoC/SoD figures?

We do compute estimates of SoC but as you probably know charge state isn't always easy to estimate. All we really know is voltage, c rate and time.

> I can sort of name ballpark figures for the above, the thing I can't get is how this can even approach profitable w/o hype and subsidies.

There is certainly risk involved with any investment. But when you are buying batteries at the scale we do the price is probably much lower than you are thinking. And if we do properly gather all the warranty data then the risk of loss on battery failure is minimized.