What's a hybrid solar DC air conditioner?

The challenge with solar, the saying goes, is that it's useless when it's cloudy or nighttime.  No sun, no power.  For the last decade or two, agreements (proving to be unstable) have been developed with local utilities allowing those with rooftop solar arrays to push their extra solar they generate up to the grid for a later credit for these dark or cloudy times.  In effect, the grid acts as a free, or almost free (depending on the public utility commission rulings in the locale) battery.  Now, homeowners are increasingly opting away from net metering and installing their own battery array.  The challenge:  These arrays may cost upwards of $800/kWh.  For instance, Tesla's Powerwall, uninstalled, comes in at about $8,500 for 13.5 kWh.  

And, 13.5 kWh isn't exactly a lot of storage.  Most homeowners need 2 or 3 of these. Yes, the cost will come down, but it's still substantial.  In most cases, it's on par with the actual cost of the solar array, if not more, once the installation is taken into account.  Lead acid batteries are cheaper, but they have the disadvantage of not being able to be discharged more than 50%, so you need around $2,500, plug the voltage controller, to get 5 kWh of workable storage.  That's enough to keep 1 ton of air conditioning running, depending on the season, for only 7 hours or something.

Airspool and other purveyors of solar-powered air conditioning noted this huge financial and implementation friction associated with storage.  Airspool uses solar when it's available during the day, and fills in any additional power demands using grid backup power.  And, at nighttime, when grid power is typically cheaper and air conditioning demands are lower, Airspool uses grid power.  So, leverage the sun when it's available, and leverage the grid to fill in when it's needed.  Solar is always prioritized.  Solar can be the only source of power if you don't want to use grid power. Even when Airpsool is plugged in, the brunt of the load is met with solar power, and the grid is used only if/when it's needed.  It's the easiest, and least expensive, way to get the most out of a solar air conditioner if and when grid power is available.

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