How long do the backup generators and batteries last if there is a blackout and the battery is drained?
How long do the backup generators and batteries last if there is a blackout and the battery is drained?
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A VERY long time if your backup generator is powered by piped in natural gas.
By the time the batteries are drained the earth will be a little bit of iron-silica gas in the sun’s outer envelope.
That brings up a major undiscussed problem with renewables:
Installing batteries to supply during frequent source outages (i.e.: night) is obvious. That’s a given when installing a system.
The issue comes with statistical fluctuations: how many standard deviations of source outage do you want to cover ... when additional battery capacity, used with diminishing frequency, is no less expensive than the baseline.
16 hours of backup battery is a given (charged during a practical 8 hours of sun).
24 hours is a no-brainer while you’re at it.
48 hours is pretty much a given, covering cloudy days.
72 hours, yeah, storms may hang out for 3 days.
5 days of backup is getting pretty expensive.
A week of storage is expensive.
You probably won’t need more than a week of batteries ... but 1 hour past that and everything shuts down, so do you keep adding on the same blasted per-day battery cost for additional days of coverage which you probably won’t need but still may happen and will seem cheap when you do need it after all?
A homeowner running his own system can make the cogent decision support X days of battery backup, accepting cost of blackout vs cost of forestalling it.
A municipality faces a MUCH harder decision, what with 1 day of additional full-capacity battery storage costing enormous sums and yet being rarely used, vs increasing odds of prolonged blackout by not buying more storage even less used.
There’s also the issue of how long it takes to recharge those batteries on top of normal usage. Basically need to install an additional full day of solar panels just to get each day of battery storage filled in time for the next prolonged cloud cover.
We live in an area where the power goes out frequently certain times of the years, sometimes for a week or more. Fortunately, we have natural gas and I converted our generator to run on that which costs a third of what gasoline does. We run it 24 hours a day 7 days a week when the power is out. I stop it once every 24 hours to check the oil level. It still typically costs us about $10 a day, compared to $2 to $3 a day normally. Gasoline was costing us about $30 a day.
Our generator is a 30 year old 5000 watt generator with a 10hp Briggs Industrial engine. It is outfitted with watt meters and an hour meter. It just keeps going and going.
Our house could probably be run with a 4000 watt generator powered by a Honda clone which would reduce our fuel costs by around 20%. Generators burn a certain amount of fuel on partial load depending on how large they are. With a non inverter style generator, when your load is greater the amount of fuel used does not go up very much. The primary requirement for us is getting a generator that provides 240 volts so that it can be more easily integrated into our service panel.