Comment by duffpkg | Hacker News Reader

Comment by duffpkg | Hacker News Reader

I have a home in the southwest that is off grid and runs on solar plus lifepo3 batteries. It has been 5+ years now. My cost per kwh is below $0.008 as of today including all capital and maintenance. These numbers get a bit complicated, for example I run the AC much colder than I would if I was paying more for it. I have extra fridges and freezers I probably wouldn't if I had to pay higher per kwh. I "throw away" a lot of power too that I am not counting when the batteries fill up.

I have about 40kwh of storage. The batteries are in steel boxes and there are some basic precautions to take with them but lifepo3 has a very manageable risk profile quite different from lipo. Batteries and solar equipment continue to get cheaper, the same system I have is now 50% cheaper today then when I bought it, including tariffs.

The link really discusses more of a single neighborhood or medium industrial site possible type of technology. Really just a huge very hot pile of sand and steam turbine or propane cell generation. On a kwh basis it is probably not competitive with solar+battery unless your use case involved a lot of direct use of hot water or heating something.

> I have a home in the southwest

> I have about 40kwh of storage

You're pretty close to the ideal location for solar + batteries. For much of Europe or the Eastern US, this amount of storage would be nowhere close to enough, by orders of magnitude - they need to make it through the winter, and generate heat from it, after all.

For each location, there's an ideal amount of storage and an ideal amount of overbuilt capacity, both depending on hardware costs (and contributions of wind to the energy mix).

In your case, both numbers are relatively small. With lower incident sun, persistent cloud cover, and the possibility of becalmed wind turbines, storage requirements can start to make thermal batteries or hydrogen storage economical.

How many hours of maintenance do spend on it on average per week? Or perhaps more appropriate if it’s rarely, per year?

Not the person you are asking, but our system is 5 years old and has required two hours of intervention work (zero scheduled maintenance).

A USB extension cable died, and it took an hour for the manufacturer to diagnose it over the phone, for me to find the right tamper bit to access it, then remove the cable.

Another time, PG&E was feeding the wrong voltage and frequency into our house. The power stayed on (our transfer switch knife cut off PG&E) but the solar array shut down because this is a weird fault. Again, it took about an hour to diagnose over the phone and fix (in this case, I temporarily turned off the PG&E service breaker. It ran diagnostics for about 30 minutes and turned the array back on).

Installation (included in purchase) was probably about 100 man hours though.

Probably a few hours per year. I occasionally vacuum the dust filters and check to make sure everything seems in order.

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