Where can I learn about solar and minisplits?

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.


Minister of Fire
Jun 28, 2014
Fairbanks, Alaska
Not asking you to teach me, I am asking about reliable websites where I can go teach myself.

Briefly, in Fairbanks, I am looking at about $4/ watt for solar install. Sun elevation is 2.6 degrees above the horizon at winter solstice, 49.5 degrees above on summer solstice. I am not putting panels on my current roof, but they could go on the south facing wall(2 story) under the eaves, down to typical snow line; maybe 6'-8 off the ground to keep them out of harms way. Roughly 40x12 feet with a deck in the way, call it 350-400 sqft of south facing wall available for panels.

Everyone I know here and at a woodworking site I frequent raves about mini splits once they have them installed. I KW juicetricity in for 3KW cooling out sounds like a good deal to me. I will be looking for a product I can hang on the wall year round, the outdoor unit needs to manage -50dF (while powered off) with good reliability. I have 1200sqft upstairs, I am thinking one distribution head in the master bedroom and one in the dining room should give me plenty of capacity for many years as summer up here gets hotter and hotter.

To do this well I would need to powerwash the exterior of my house, put up a vapor barrier, install hardpoints for the panel and minisplit install, then new siding over the barrier, then install the minisplits and solar planels. I would plan to execute most of the installation myself so the wall penetrations are done correctly, but am not adverse to having an HVAC person sign off on the install and charge up the lines.

FWIW my main breaker is 100amp, my cable runs under a paved street to 'my' transformer.

I am in the weeds here, if you can help separate the wheat from the online chaff I would be most grateful. Thanks.
Some comments

I really do not know if any firm is going to guarantee -50 F. I know my Mitsubishi has survived -32 F a couple of times in Northern NH (not running). My place routinely sees -20 to -25 every winter. My guess is tubing connections need to be perfect with that sort of temp range. You od need to mount the outdoor units to under a roof or an overhang, snow sliding off a roof could damage them and water dripping off a roof and freezing at night inside the unit could be bad.

The two top tier brands seem to be Fujitsu, Mitsubishi with Daiken very close.

COP (efficiency) varies by brand and particular model, many are rated at or near full capacity heating down to -12F but the COP Is down to the point where electric baseboard is similar efficiency. The COP does not measure heating quality, down at very low temps the unit is moving a lot of air around and heating it a small amount, dependent on outside conditions it will be defrosting a lot which is noisy. My experience and others in northern NH and Maine is somewhere in the range of 10 to 20 F they switch to other heating sources. For cooling they are hard to beat although multiple head units usually have lower overall COP than single head units.

I wonder if your ground temps are high enough for geothermal?. I remember a place call Chena Hot Springs had dome of hot rock under it and they have a "backwards heat pump" to generate power https://chenahotsprings.com/renewables/ . I do not advocate actually producing power but if you have "warm" ground water a ground source heat pump can put out heat at any air temp and potentially cooling (depends on how warm the ground water is). Not cheap to install as you need a lot of boreholes and piping but something to consider. Most geothermal systems put out warm air versus hot water.

PV Watts, the tool for figuring out potential electric power production is great free tool for PV sizing but it does have limitations you need to be aware of. It is based on database of long term solar sampling data, if your local conditions vary from whatever the nearest data point is , the program does not take than into account. My guess is with wall mount panels with an overhang, you have serious shading issues during the summer with high sun angles, PV watts does not have an option for overhangs so there could be a lot of the summer where the top of the panels are shaded. This site can give you the sun angle during any day of the year https://aa.usno.navy.mil/data/AltAz. With a lot of cad time you could figure out the optimal fixed overhang that is enough to keep the panels out of the snow but not too much that summer shading is an issue. My guess is you need a multistory vertical wall for it to work but its going to require modeling.

Tracking solar arrays do not have the overhang issue and will optimize the sun angle and can deal with snow as long as the installer plans in an extra tall base (lots of concrete). Check out All Earth Renewables in VT for one type built for snow. A manually adjustable angle pole mount out in the open could get adjusted to near vertical although its going to vary by manufacturer. My home brew version is probably limited to around 10 degrees from vertical. Even vertical panels can build up snow in the right conditions so plan on having to clear them off with "soft" rake on occasion. When I see various Alaska installations I see a lot of manually adjustable angle pole mounts.

Further complicating things is PV Watts does not factor in reflection from snow in winter which increases panel output potentially over the panels rating, this is a good thing but it adds a wrinkle to sizing string inverters. Its less of an issue with microinverters, although clipping can be an issue. If the panels go on a roof or are subject to shading microinverters are the way to go, they are more expensive than string inverters and less reliable as the micros are mounted behind the panels in a potentially hot locations (in summer).

A god basic primer on solar is Solar Power Your Home for Dummies, there is an older version somewhere on the web or you can buy used or new copies on Amazon.

So you definitely have a lot of homework to do.
So are you doing this to save money or be green? Planning grid tied or off grid solar install? Any batteries? I would really want to have my system running a few things if the grid goes down.

I’m in a similar situation even bought solar for dummies but haven’t read a page yet. I don’t have a great location due to trees that will keep growing.

After reading the solar dummies book I was going to start reading up on electric code.

If this about money what would two window units cost to buy and run for 5 years? Planning on heating with the split I imagine?

Residing would you add more insulation too?

This channel has some good general info. Seems like he has turned the commercial corner and is selling components. https://youtube.com/c/WillProwse
If the plan is to move in the next few years then thinking about the ROI should be primary. Also, not sure if hanging a bunch of solar panels on the side of the house would negatively affect the resale value, but I suspect it would. Ask some realtors.
@EbS-P , I don't know enough to answer any of those. If we keep this house I am going to install AC, my goal is to buy some kind of solar system rather than just consume more kwh than I already do. I suspect, given the existing constraints on garage space I would use the grid as my battery.

If/when we have an EV in the future I would expect it to be able to power at least some circuits in the house during power failures. I need up to 20amps start up and 5 amps run for my oil fired boiler for starters. I have never actually measured startup current draw, but it has never blown the 20A breaker it sits on. Being able to charge the portables and watch a DVD on the home theater system would be nice. Probably the fridge. I have too many freezers already and took up canning this year as canned goods need no ongoing maintenance.

Not doing window AC, not going to look up how much it would cost. My walls are drywall - vapor barrier - 2x6 studs with fiberglass batt - T-111 siding - latex paint. If I start running AC without sealing up the exterior surface of the wall I will get behind on the black mold battle in my 1980 build and that would be prohibitively expensive.

@begreen , you raise a valid point. There are several roof top systems in my subdivision. I look at those things in the spring melt when the snow gets to sliding around and shake my head. I will check in with a couple realtors before I commit to a plan. I would like to list and get under contract spring 2023. I am getting too old to be hauling 8 cords of wood upstairs to the stove every winter. This winter I will be deciding if I need to move south for my joints, or try to hang on up north a little bit longer. My metabolic rate belongs up here, my joints belong in the Caribbean. I am growing bone spurs faster than the Arctic is warming. If interest rates and house prices keep inflating we would be sitting on a nice egg of equity but no good way to pay off a new mortgage at higher interest before retirement.

Thanks for the various pointers, I will get started on my homework. BTW, winter is coming, I felt it in my joints this morning. I was sweating by 1100, but my seasonal stiffness is already returning. Autumn caribou season opens in 19 days, less than three weeks away.
  • Like
Reactions: EbS-P
@peakbagger , Chena Hot Springs is about 60 miles out in the country on the other side of town, 70 miles or so one way for me. I am somewhat familiar with it, but in a regular old 'murican subdivision on a lot a bit under 10k sqft. I have 10 foot utility easements front and back on my lot, very little room to be drilling boreholes. I am between the Chena River and Chena Ridge on the west side of town, about three miles upstream from the historic (archeologic) village of Chena. To get to my house you have to drive on Chena Pump Road. Very little creativity up here when the town got built out.

I am not really looking to heat with solar I don't think. I have a new oil boiler this summer with decent efficiency and an excellent wood stove. Shoulder season, sure, use the solar to make a little heat with the minisplits. I have an outstanding wood stove, with 8 cords in the back yard ready to burn a month ago.

The units do have to overwinter outdoors. No way am I going up on a ladder two times a year, making room in the house for the outdoor units, and redoing the tubing connections over and over. Not happening.

I do fool around a bit with Arduinos and have built a desk top solar tracker. Not happening here with a full on outdoor install. I will pick a fixed angle that works well in the hot months when I need AC and maybe get a few bones back from the utility the rest of the year. Mounting a bunch of servos on the wall and leaving them out there all winter, no. A manual system with a stick and three or four fixed angle positions, nope, not me. If I had some acreage up here with near ground level panels I could see a three angle system, one for winter, one for summer and an intermediate notch in the sticks for spring/autumn. Winter this far north is very hard on electronics, but you kinda know more about that than most already. I am at 64, almost 65 degrees north latitude.

Thanks again everybody. I will get going on my homework.
I feel for you. As predicted, planetary heating is most extreme at the poles. Age is also pushing me to examine alternatives for heating. We'll be using the heat pump more this year. Going up stairs repeatedly with full armloads of wood gets hard on the knees. Probably won't start wood burning until temps drop below 40ºF unless I carry the wood through the house to the porch woodbox.