Author Topic: Off grid mini-split installation  (Read 292 times)

WillEert

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Off grid mini-split installation
« on: October 24, 2018, 12:06:47 PM »
Following last summer, despite passive cooling of our house at night, we decided to install a heat pump. Luckily for us, a new product had come on the market, which is a PV direct mini-split heat pump. This unit operates stand alone, directly connected to a suitable array, with no need for batteries or a charge controller. Obviously it will not operate at night or when there is not enough insolation to run it. It does take quite a bit of over paneling so it will run in low light conditions.
I did the install myself. A local heating company loaned me all the required test gauges, manifolds, nitrogen tank and offered advice as needed. I could not have done the commissioning without their help. Knowing what I know now I would do the shop installation differently but that is what happens as you learn.

Initially I am very pleased. I installed two of these units - one on our shop building and one on our house. The pictures are of the shop install. The array is 6 mono 345 STC panels in series for 2070w. The units need about 1000w to operate at 100% duty. My tilt angle is definitively summer oriented. The units are very quiet, both inside and outside. The company documentation is not that good and their knowledge about how the units actually work is quite poor. Midnites support for their products is far superior. I had to unsolder a "beeper" from the indoor units circuit board that was driving me crazy. The units can function as a hybrid system using 240V AC when enough DC is not available. Sometimes they will be running on both AC and DC. I do not think the "beeper" would be an issue in this case. The vendor offered me a replacement board with beeper removed to swap out but I wanted to get it done so did the work myself.

The units are making good heat at the existing ambient temperature +7C to -3C. The COP at 0C is said to be 3.6 and at -15C 2.7. I am not sure what will happen below -15C. This winter will tell. Photos of the installation attached. Very pleasing to have an automatic stand alone heating / cooling system as an offgridder. Luxury!!

Will
(1) 24 ET 185 mono, Classic 150,8x Surrette 6CS25p, 3x Magnum 4448, homecooked diversion system;
(2) 15 Heliene 330 mono, Classic 150; (3) 2 X 6 Hansol 345 mono, 2 stand alone Hotspot ACDC12C Mini-split heat pumps.

Fastest1

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Re: Off grid mini-split installation
« Reply #1 on: January 09, 2019, 06:17:37 PM »
Are you using six panels per unit? What ton unit is that? Does it have multi zones? Nice set up it appears.

WillEert

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Re: Off grid mini-split installation
« Reply #2 on: January 17, 2019, 08:54:48 PM »
I am using 6 X Hansol 345 Mono panels. The unit states 12000 BTUhr for heating and cooling which is about 1 ton of refrigeration. This ouitput will vary with the temperature difference between inside and outside. The specs say a COP of 3.7 @ 0C which is the 1 ton. They told me 2.6 @ -15C. So far they have started and run, producing some heat at -23C. Supposed to be -30C tonight and sunny tomorrow so I will see what they will do then. These minisplits  are one zone units.

Will
(1) 24 ET 185 mono, Classic 150,8x Surrette 6CS25p, 3x Magnum 4448, homecooked diversion system;
(2) 15 Heliene 330 mono, Classic 150; (3) 2 X 6 Hansol 345 mono, 2 stand alone Hotspot ACDC12C Mini-split heat pumps.