US 11,867,412 B2
Device and method for converting solar PV energy into thermal energy storage using combined heat-pump and resistive heating elements in water heater
Yusuf Gurkaynak, Arvada, CO (US); Nikola Milivojevic, Boulder, CO (US); Keegan Landreth, Longmont, CO (US); and Michael Dean Steingrebe, Longmont, CO (US)
Assigned to PREMIER ENERGY HOLDINGS, INC., Frederick, CO (US)
Filed by PREMIER ENERGY HOLDINGS, INC., Frederick, CO (US)
Filed on Dec. 22, 2021, as Appl. No. 17/559,898.
Claims priority of provisional application 63/129,444, filed on Dec. 22, 2020.
Prior Publication US 2022/0196251 A1, Jun. 23, 2022
Int. Cl. F24D 19/10 (2006.01); F24D 12/02 (2006.01); F24D 11/02 (2006.01); H02S 40/30 (2014.01); F24H 4/04 (2006.01); H02P 27/08 (2006.01)
CPC F24D 19/1045 (2013.01) [F24D 11/0221 (2013.01); F24D 11/0228 (2013.01); F24D 12/02 (2013.01); F24H 4/04 (2013.01); H02P 27/08 (2013.01); H02S 40/30 (2014.12)] 21 Claims
OG exemplary drawing
 
1. A system comprising:
a solar photovoltaic system;
a DC/DC power converter connected to the solar photovoltaic system to extract maximum power from the solar photovoltaic system and power a DC bus;
an electric heat pump-based heating device coupled to heat a thermal mass;
a resistive heating element in the electric heat pump-based heating device coupled to heat the thermal mass;
a variable frequency (VFD) motor drive coupled to receive power from the DC bus and having at least a first phase output coupled to the electric heat pump-based heating device;
the resistive heating element connected to resistive power control apparatus selected from a pulse-width modulator and a DC-DC converter;
wherein the DC/DC power converter, the VFD, and the resistive power control apparatus are coupled to be controlled by a microcontroller;
sensors adapted to measure current, voltage, and temperature coupled to the microcontroller;
wherein, the microcontroller is configured by firmware to:
monitor solar power available and
if solar power available is less than a first threshold, operate the resistive power control apparatus to use power available in the resistive heating element;
if solar power available is greater than the first threshold, use the VFD to use the solar power available to power the electric heat pump-based heating device at a frequency and an AC voltage increasing with solar power available, the frequency limited to a maximum frequency and the AC voltage limited to a maximum AC voltage; and
if solar power available is greater than sufficient power to use the VFD to power the electric heat pump-based heating device at the maximum frequency and the maximum AC voltage, to operate the resistive power control apparatus to use that portion of solar power available greater than sufficient power to use the VFD to power the electric heat pump-based heating device at the maximum frequency and the maximum AC voltage to drive the resistive heating element.