Solar energy powers this off-grid air conditioner
S. Himmelstein | July 20, 2023
Schematic of the proposed system comprises the power source, energy storage and the VCC. Source: Cleaner Energy Systems/CC BY 4.0
The technical feasibility of a mini-split air conditioning unit powered solely by off-grid solar power and battery storage has been demonstrated by researchers from the U.K.’s Ulster University.
Designed to utilize low global warming potential (GWP) refrigerants, the system consists of two 400 W solar panels, two 130 Ah lead-acid batteries and a vapor compression cycle (VCC) unit. The external unit incorporates a compressor, a condenser, an expansion valve, and the two batteries connected in parallel with a charge controller and inverter. The internal unit includes an evaporator, external ducts and an indoor canopy.
Tests simulating the hot climatic conditions typical in Middle Eastern nations confirmed that the batteries charged by solar panels are capable of supporting the air conditioning unit during the night. GWP refrigerants R600a and R290 were identified as optimal candidates to replace the commonly used R134a and R410A. The use of R290 resulted in a substantial increase in coefficient of performance and exergetic efficiency.
After being fully charged, the batteries can power the system for seven hours, indicating the practical feasibility of the solar powered off-grid air conditioning system described in Cleaner Energy Systems.
Could it lower the temperature by 20 degrees F in a 1500 Sq Ft. well insulated house in the U.S.? Say, from 100 degrees to 80 degrees?
I live in Australia at the moment it is winter. I have built my own Hybrid system and run a Fujitsu Inverter Split system. The aircon has a COP of about 3 and draws a Max of 2.4KW but heating is around 7KW at outdoor temp of 4 deg C. At around 9pm I turn Grid off Aircon keeps my small house (uninsulated, typical for Old houses in Australia) at 22 deg C for about 12 hours with my 15KWh Lithium Fe batteries. Then I turn grid off since in Winter only getting about 6Khrs per day from Sun but it certainly helps. I think with a 8KW array I would be OK.
With your situation in USA with extra Sun you would be in cooling mode a unit like mine would easily cool your home say a couple of rooms. I love these modern heat pumps, they automatically adjust the compressor. There is so much wrong information about modern heat pumps. The technology is getting better all the time and are even handling temps down to -15 deg C using CO2 has the refrigerant with a COP of about 2.
About 10 years ago I visited a remote station in Australia outdoor temp was 40 deg C the main building was running two split aircons indoor temp was 20 deg C. Station was entirely off Grid. 10KW of solar panels. Renewables are the future.