Advice on potential solar array and heat pump
i am considering having a solar array and heat pump with 4 head units installed, I’m looking for advice on if this is sized correctly.
The proposed solution
Solar Array: 21 LG330N1C‐A5 panels with Enphase IQ7 micro-inverters to generate 8,438 kWh annually
Heat Pump:
MXZ–4C36NAHZ-1 410A to power 4 wall units – MSZ-FH12NA-8 – that are located in the two upstairs bedrooms, the downstairs bedrooms, and the kitchen (which is an addition to the original house built in 1900).
I currently have a single pipe steam radiator system with oil fired boiler that I am hoping to use only to heat our living room and dining room, allowing the wall hung units to heat the rest of the rooms in the house.
My current average energy consumption is ~350kWh monthly.
Will the proposed solution allow me heat a good portion of my house while still cancelling out my electric bill?
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Replies
J. Well,
If you install a minisplit head in each bedroom, you will (in virtually all cases) be oversizing your system. Before you can design a heating or cooling system, the first step is to perform a heating and cooling load calculation. Have you done that yet?
You are currently using 4,320 kwh of electricity annually. It's impossible to say whether a PV system generating 8,438 kwh annually will "cancel out your electric bill" without knowing:
1. The details of your local utility's net metering agreement.
2. Your climate zone.
3. Your design heating and cooling load.
Specifically, you should have a "Manual J" and a "Manual S" analysis (plus #1 above).
A very rough rule of thumb (which includes all kind of assumptions about the efficiency of the existing system, distribution losses, your climate zone, etc.) is that each gallon of oil you displace with an 11.3 HSPF minisplit will increase your electric use by about 10 kWh.