Bar Chart of Shame: Planning for solar installation....and heat pumps?

As the title indicates, some planning with a local solar PV installer necessitated getting estimates on current, grid-supplied electrical power consumption.  The 'bare all' graph below speaks for itself....huge consumption in the winter months and some plateauing during the summer.  The large power hogs: 2 X 7 kW electrical garage heaters that are both on a few hours each night for wife's animal feeding chores, an 80 gal. standard (20 yrs old?) electric hot water heater in a poorly insulated basement, and an electric stove/range.  One standard ~20 year old fridge/freezer in the kitchen and toaster/air fryer/microwave all participating in the feeding frenzy, but for short periods.  Significant summer draws are from the kitchen fridge as well as 4 chest freezers in a pretty warm (summer....uninsulated) garage.

So the potential installer noted that he sized the quoted system for 10 kW based on an average annual ~14000 kWh consumption.....and that we could do much to shave off the size of the system if we could flatten out our graph below during the winter months.  This brought up the idea of leaving the garage heaters off for the most part if we were to add air-sourced heat pumps in those animal buildings.  He offered that the technology has improved significantly and I recall a different thread here about heat pumps reflecting those advances.  So here I'd just like to ask for those in winter climates with regular evening temperatures dipping below zero F, if you have a newer heat pump, has it performed 'well enough' down around or below zero?  We'd be happy enough just to use the older 7 kW heaters on nights that are around -20F or lower if the bulk of the days/nights are warmed by the heat pumps.  Second related question pertains to replacing the older electric hot water heater with a heat pump water heater.  They seem to have decent reviews and appear to have a similar lifespan (?) while drawing less power.  Would be grateful for comments about these water heaters from those who have used them in the past few years.  The result would be possibly re-configuring the solar PV system a bit smaller....sort of like buying those tight jeans so that you *must* lose the weight to fit into them! :-)   There are some sizable rebates and tax incentives in the U.S. for installing some of these heat pump technologies now as well.  Thanks!....

It doesn't look like we've got many people with experience of heat pumps. I must admit I don't really trust them, I just think there are too many things to go wrong, and a lack of servicability/ future proofing.
If I was going to reduce my electric heating costs I would look for non electric means of heating. I know the heat pumps are basically fridges rather than heaters so use less electricity to achieve the heating effect. Most of our heating is done with our wood stove, I expect you will already have considered that. Any chance of using the waste heat from 4 freezers to heat the animal feeding areas a bit?

Hey John, somehow I missed your post. Good questions -- relevant stuff! Let me think on it.

Well done Nancy in giving this post a bump.

Summer Months vs Winter Months
It looks like you use about 5x more per month in the winter vs in the summer. So I am not going to worry too much about the things that you use year round.

Hot Water Heater - Basement
If you are losing heat from the hot water tank, why not just get rid of it and install a instant hot water heater under the sink/basin/etc.
How much would it cost to improve the insulation of the basement?
Heat Pump Hot Water Heaters are great in the summer they help lower the hot summer air, they are horrible for the winter they help chill the already cold house, the solution would be to have the unit collect the needed heat from outside the building (mini-split setup or geothermal setup).

Garage Insulation
How much would it cost to insulate the garage, esp for the winter?

Garage/Wife Heating
How much would it cost to better insulate the garage?
Why exactly are you heating the garage again for 3hrs+?
The animals body don't actually need the heat, there are lots of breed that survive perfectly fine in even colder conditions.
If its just your wife that needs the heat it is possible for her to spend 50% less time in the garage to feed the animal, how can things be streamlines?
Is it possible to only heat your wife and not the entire building, esp the fingers, neck and head, they have heated jackets esp for motorcyclist?
Another way to only heat your wife is with over heat, radiant heater, you might have seen them at train stations or bus stops, would that work?
Is there a more streamline way to keep the animal water deiced, vs heating the entire building?

Heat Pump
You will get a 2x boost so instead of needing two 7KW resisitive heater, you can use just a single 8KW (10-ton) heat pump.
If it was a geothermal setup you could have reduced it to a single 4KW(5-ton) heat pump.

Solar Panel Sizing
If the average person has a 10KW solar panel array, but they heat with fossil fuel, due to the fact that you are also heating with electric you can't follow their sizing. Hot Water Heating and Space Heating/Cooling has a 3x load when compared to just the usual (heating/tv/computer/fridge/washer/etc). So you are probably going to need a 4x of the usual solar panel size. Under theoretical conditions with a perfect geothermal heat pump setup that has a COP of 3, you could heat your house+water with an extra 1x load vs 3x load and thus only need to size your solar panel at 2x 10KW vs the more normal 4x 10KW. Did I mention that a geothermal heat pump setup cost alot more than just a regular AC/Heat Pump, due to all the drilling and piping.

Nancy Reading wrote:It doesn't look like we've got many people with experience of heat pumps. I must admit I don't really trust them, I just think there are too many things to go wrong, and a lack of servicability/ future proofing.
If I was going to reduce my electric heating costs I would look for non electric means of heating. I know the heat pumps are basically fridges rather than heaters so use less electricity to achieve the heating effect. Most of our heating is done with our wood stove, I expect you will already have considered that. Any chance of using the waste heat from 4 freezers to heat the animal feeding areas a bit?

So, interestingly my main HVAC installer that we've used for a few decades echoed the same opinions on air-sourced heat pumps.  He offered that he could install one if that's the way we wanted to go, but he too was concerned about longevity vs savings in the long run.  Our age and capabilities are such a factor here.  The two buildings needing the most heat are both places where my wife spends 3-4 hours each night and in the winter these spaces are cold (0C or less).  Oddly enough the largest building (steel barn/building with good insulation) likely draws on the electric heater less than the much smaller, uninsulated building where she makes up the food for the animals.  (Smaller building has water source, larger warmer building does not.) Wood heat was a temporary option but the way wife likes her space and time organized, the woodstove was at risk of being bumped by animals and was just one extra thing she did not want to have to tend to at this point in her life.  In the past week, with the flurry of planting and late spring activity behind us, our attention once again is upon this issue and how to re-furbish and reconstruct the food prep area for the animals.  It's only 20 X 12 ft., but leaks like a sieve and this will be the major project for late summer early fall insulation efforts.  With a dirt floor and that small space, it's not practical to have the chest freezers in there to provide waste heat.....not to mention they don't turn on at all when it's routinely between -15 and -20C.

In the end and with improved efficiency, declining cost, and an impressive subsidy for heat pump installation offered by our electrical utility, I may spring for installation myself of a small, wall-mounted air-sourced heat pump just to see how well it would work in this scenario.....could always be re-purposed in the home for AC if it's of no use for heating.  More comments to follow and to address S. Benji's suggestions below.  Thanks for the ideas, Nancy!

Where is this located?  Even passive solar thermal might help.

Not sure if 10 kw solar is the best fit, but not sure what your goals are.

How about a pellet stove or RMH?

Maybe a smaller 1-2 kw solar electric/thermal system?  

You could also run a generator on natural gas, biogas, biodiesel, for heat and electricity. Although an engine is likely noisier than a pellet stove.

Can you shave needs off in other ways before worrying about the PV part.

Solar thermal is 3X to 4X more efficient than PV.  Battery can be simple mass be it dirt, sand, rock, concrete,  water.  Roughly 50% to 70% of your household needs are thermal in heating, cooling, domestic hot water

Here is my first steps.  More to add here but all thermal solar air.

solar collector

Worst case looking at 100 watts to run fans.  Current peak is 70 watts.(better fans would bring it down to 50)  Neat thing here is most of the power consumption is only needed on days the sun is shining during those hours so ideal for pv.  Rest will need batteries too.


Next step is solar thermal water for hot water heating.  Large insulated box tank as a preheater for the hot water heater.  Looking at 300 gallons roughly in a non pressurized storage heated with a double pane window glass collector.  Looking at the info suggests tank suggests that for a family of 4 it gives 1 1/2 days of heat storage.  By myself I should be able to get 4 or 5 days out of it.  Will only heat the stored water to 140-150 degrees.  If I can add another collector either evacuated tube or optical concentrator so I can take that tank temperature on up that might be doubled.  Lets say this system might include 4 pumps at 30 watts each.  1 for main collector, 1 for high temperature collector, 1 for a ground loop so the other 2 can be oversized for better heat recovery and 1 final pump for household heating in winter used only to maintain some minimum temperature.

Then simple geothermal ground loop system for cooling and boosting the minimum temperature the house reaches when heating.  Information suggests I will likely need 400 feet to 600 feet of buried 3/4 inch black poly line for 12,000 BTUs of cooling.  Looking at the climates and soil temps of the people providing that information guessing I am closer to the 400 for 12,000.   Soil temperature here is approximately 56 degrees F.  On the worst summer I remember the 18,000 BTU window air conditioner was almost keeping it comfortable.  Lets pretend I buried 3 zones 300 ft long.  The pump information for the pump of interest suggests I can run 400 feet of line and get enough flow.  So lets assume the other 100 is in a ceiling loop inside the house.  If you do the math on surface area for those 3 loops that is equivalent to a 2 foot square radiator 2 inches thick with 10 fins per inch which is slightly more than the AC evaporator size.  By spreading it out in the hottest part of the house up high the hope is I can cool without needing a cooling fan.  Most of the year the house will almost maintain by simply opening windows and cooling off at night and closing up tight for the day.  Gets too warm late in the day and into the evening.  But cooking/canning wrecks that and we have 2 to 6 weeks where it typically doesn't cool off enough at night to cool the house off.  Now if I want to run a desiccant air conditioner on top of that would want 3 more pumps and another ground loop.  So potentially another 180 watts of pumps here.

So for potentially 400 watts of power I should be able to heat the house, heat the majority of my domestic hot water, boost the clothes drier input temperature on sunny days, do an HRV air circulation system and air condition the house for the summer and  have most of that power only needed during sunny days.  That looks way more doable on the PV end.  My primary batteries are concrete, soil and water and should never wear out.  Buried water lines should have a 50 to 100 year life expectancy at the very least.   Pumps are low voltage DC, magentic drive so no seals to fail and information puts their MTBF in the 20,000 hour range.  Relatively cheap rebuild kits should get them out to the electronics and winding failure points which should be in the 60,000 hour range if treated well.  The fans for the system show a 70,000 hour life expectancy for the good ones.

Where is this system going to fall short?  1.  Domestic hot water is the most obvious.  I have maybe 10 days of storage at best.  But my longest gray winter day run since I started watching it was 17 days with only about 6 hours of good light in that time.  If I can get an evacuated tube collector even on gray days it will do a little.  But I likely need another fuel source to heat hot water on occasion during the winter.  RMH with a convective loop to my hot water tank?  Small propane instant on heater with a pump heating my water tank?  Wood fired outdoor boiler?  Other answers?  2.  Will likely need to swing slightly more temperature range that most people are comfortable with.  I still think it can probably hold in a 60 to 80 degree F range for the house temperatures with a bit of work.  It will not be the 65 degree summer day, 75 degree winter day locked temperature most people seem to want any more.

John Weiland wrote:As the title indicates, some planning with a local solar PV installer necessitated getting estimates on current, grid-supplied electrical power consumption.  The 'bare all' graph below speaks for itself....huge consumption in the winter months and some plateauing during the summer.  The large power hogs: 2 X 7 kW electrical garage heaters that are both on a few hours each night for wife's animal feeding chores, an 80 gal. standard (20 yrs old?) electric hot water heater in a poorly insulated basement, and an electric stove/range.  One standard ~20 year old fridge/freezer in the kitchen and toaster/air fryer/microwave all participating in the feeding frenzy, but for short periods.  Significant summer draws are from the kitchen fridge as well as 4 chest freezers in a pretty warm (summer....uninsulated) garage.

So the potential installer noted that he sized the quoted system for 10 kW based on an average annual ~14000 kWh consumption.....and that we could do much to shave off the size of the system if we could flatten out our graph below during the winter months.  This brought up the idea of leaving the garage heaters off for the most part if we were to add air-sourced heat pumps in those animal buildings.  He offered that the technology has improved significantly and I recall a different thread here about heat pumps reflecting those advances.  So here I'd just like to ask for those in winter climates with regular evening temperatures dipping below zero F, if you have a newer heat pump, has it performed 'well enough' down around or below zero?  We'd be happy enough just to use the older 7 kW heaters on nights that are around -20F or lower if the bulk of the days/nights are warmed by the heat pumps.  Second related question pertains to replacing the older electric hot water heater with a heat pump water heater.  They seem to have decent reviews and appear to have a similar lifespan (?) while drawing less power.  Would be grateful for comments about these water heaters from those who have used them in the past few years.  The result would be possibly re-configuring the solar PV system a bit smaller....sort of like buying those tight jeans so that you *must* lose the weight to fit into them! :-)   There are some sizable rebates and tax incentives in the U.S. for installing some of these heat pump technologies now as well.  Thanks!....

HI John, I attached my heat pump consumption for our 2600 square ft home for the last 18 months. Heated to 21 degrees celcius and cooled to the same year round.  Most of it has been mentioned above. Insulate rather then generate is a good catch phrase. We used to call then "negawatts" in the energy geek world. The idea is to rethink you setup, maximize its efficiency THEN figure out consumption.  Heat pumps are a great technology but they work best maintaining a steady state especially in the winter. As the temperature difference between out and in increases they are less and less able to apply quick changes in heat. In your case sporadic increases in temp in a uninsulated structure would be a bad application for them.  I would go infrared above head lamp for warming the person not the structure or workbench focused concentrated heat or heated clothing.
Cheers,   David  

John Weiland wrote: our attention once again is upon this issue and how to re-furbish and reconstruct the food prep area for the animals.  It's only 20 X 12 ft., but leaks like a sieve and this will be the major project for late summer early fall insulation efforts.

If this is where the biggest proportion of the energy is going then it looks like that will be time/money well spent!
One thought is that a electrically heated (insulated) slab floor may be worth considering. If you could heat this with some of your surplus solar in the late afternoon (thermal storage rather than battery storage?), that could slowly release during the night to keep the water etc. at a better temperature.  As C. Letellier also said, any solar thermal that can be achieved and stored for space heating would be useful - a glazed porch, or a trombe wall for example.

Thanks for all responses, insights, and recommendations here.

I agree that 'stop-loss' measures will be the first to implement.  As we are getting older and the equation of r.o.i. becomes more of a factor with limited time remaining (20-25 years?), a prioritized insulation programs seems to be the best way to go.

Spring, Summer, and Fall months really are not so much of an issue.  Sure, the heat in the main garage where the chest freezers are kept gets too warm and makes them work harder than they need to, but that pales in comparison to the winter heating woes in the one building that needs the most insulation.  So that is where the focus will go.  I'm really not sure how to relate the difficulty of the core 2 months of winter with regard to passive solar.  With the frost depth at a reliable 4-5 feet deep and the short-day, low intensity of the sun just south of the Canadian border, I liken it to an ice-box where heat retention will be short lived.  As noted, the larger barn is well-insulated and probably takes less heating to bring it into a comfort zone, after which it returns to the 30s-40s F for the remainder of the day/night.  No hot water is required in these buildings and a single water hydrant (plumbed below the frost-line) is the source for water for drinking and food prep for the animals.  For sure I will be looking into infrared overhead heat lamps as a supplement where wife preps food.....had just started to try these out a few years back in a larger 40 X 80 ft quonset before that collapsed from snow-load.  [The insulated barn was its replacement building.]

The face of the small food prep building that faces south is about 6 ft tall X 20 ft long.  After it was installed, it could be quite cozy in there during bright sunny days, even when around 0F outside and even during short days.  The *appearance* at least is that we don't seem to have as many bright sunny days in December-February as we once did.  Additionally, over time, the south wall, comprised of twin-wall polycarbonate greenhouse window glazing, has become cracked and frost heaving has caused many gaps and cracks to form along seams of the structure.  Clearly, addressing all of this in a thorough way is a major part of the project.  ,For those in similar latitudes and peak sun hours in winter ..... *and* length of non-sun periods with temps around 0F (~ -17C)...is a thermal battery even practical under these circumstances?

A layout of the buildings and production estimate (PV solar) from one provider for our location is shown.  The latter was done with matching our *current* usage in mind and I'm hoping reductions on our end could then reduce the need for the number of panels and size of the system.  One last question I will just throw out refers to wind power as we are in a moderate to high wind region, yet our property with trees and buildings would require an 80' tower minimum to avoid turbulence.  It seems that the superiority of horizontal wind turbine for power efficiency is no longer contested (???) but that the superiority of vertical axis wind turbines for withstanding turbulent winds remains agreed-upon.  Would adding lower-altitude, vertical axis wind-based electrical production make any sense in a high-wind, high-turbulence environment as a supplement to the solar deficit that occurs in winter?  Although a downward trend in wind speed has been recorded in the region since the 1950s, monthly averages are still around 12 mph with July/August being the least windy (and still solar strong) while March/April being the windiest.

Finally, with our abundance of free wood on the property, wood heating (as we do for much of our home heating) would seem to be a no brainer.  But here is where the age issue comes in and is one more thing that wife does not want to have to deal with along with the 4 hrs of animal feeding each night, 365 days/year in her advanced age.  So with the years remaining, we are looking to make do with what is available and as low energy footprint as possible.  Thanks again for all comments especially has they reflect so much experience already in these areas and dealing with similar issues.

John Weiland wrote:Thanks for all responses, insights, and recommendations here.

I agree that 'stop-loss' measures will be the first to implement.  As we are getting older and the equation of r.o.i. becomes more of a factor with limited time remaining (20-25 years?), a prioritized insulation programs seems to be the best way to go.

Spring, Summer, and Fall months really are not so much of an issue.  Sure, the heat in the main garage where the chest freezers are kept gets too warm and makes them work harder than they need to, but that pales in comparison to the winter heating woes in the one building that needs the most insulation.  So that is where the focus will go.  I'm really not sure how to relate the difficulty of the core 2 months of winter with regard to passive solar.  With the frost depth at a reliable 4-5 feet deep and the short-day, low intensity of the sun just south of the Canadian border, I liken it to an ice-box where heat retention will be short lived.  As noted, the larger barn is well-insulated and probably takes less heating to bring it into a comfort zone, after which it returns to the 30s-40s F for the remainder of the day/night.  No hot water is required in these buildings and a single water hydrant (plumbed below the frost-line) is the source for water for drinking and food prep for the animals.  For sure I will be looking into infrared overhead heat lamps as a supplement where wife preps food.....had just started to try these out a few years back in a larger 40 X 80 ft quonset before that collapsed from snow-load.  [The insulated barn was its replacement building.]

The face of the small food prep building that faces south is about 6 ft tall X 20 ft long.  After it was installed, it could be quite cozy in there during bright sunny days, even when around 0F outside and even during short days.  The *appearance* at least is that we don't seem to have as many bright sunny days in December-February as we once did.  Additionally, over time, the south wall, comprised of twin-wall polycarbonate greenhouse window glazing, has become cracked and frost heaving has caused many gaps and cracks to form along seams of the structure.  Clearly, addressing all of this in a thorough way is a major part of the project.  ,For those in similar latitudes and peak sun hours in winter ..... *and* length of non-sun periods with temps around 0F (~ -17C)...is a thermal battery even practical under these circumstances?

A layout of the buildings and production estimate (PV solar) from one provider for our location is shown.  The latter was done with matching our *current* usage in mind and I'm hoping reductions on our end could then reduce the need for the number of panels and size of the system.  One last question I will just throw out refers to wind power as we are in a moderate to high wind region, yet our property with trees and buildings would require an 80' tower minimum to avoid turbulence.  It seems that the superiority of horizontal wind turbine for power efficiency is no longer contested (???) but that the superiority of vertical axis wind turbines for withstanding turbulent winds remains agreed-upon.  Would adding lower-altitude, vertical axis wind-based electrical production make any sense in a high-wind, high-turbulence environment as a supplement to the solar deficit that occurs in winter?  Although a downward trend in wind speed has been recorded in the region since the 1950s, monthly averages are still around 12 mph with July/August being the least windy (and still solar strong) while March/April being the windiest.

Finally, with our abundance of free wood on the property, wood heating (as we do for much of our home heating) would seem to be a no brainer.  But here is where the age issue comes in and is one more thing that wife does not want to have to deal with along with the 4 hrs of animal feeding each night, 365 days/year in her advanced age.  So with the years remaining, we are looking to make do with what is available and as low energy footprint as possible.  Thanks again for all comments especially has they reflect so much experience already in these areas and dealing with similar issues.

John,
It sounds like you have the rough plan figured out.  A few thoughts as I read through it all
As influenced as I was with all the passive solar and thermal mass books I read from the 70's and 80's thermal mass and solar thermal simply have not panned out in our climate. Works great in higher altitude cold winter/sunny days areas but here with our 6-12 weeks of grey cold, lake effect snow its a non starter.  I totally agree that we seem to be getting more less cold but cloudy winter days than in years gone past. Insulation has proven to be the best bang for the buck... I could see someone on site suggesting a rocket mass heater/food prep bench which you fire up when you prep and coast til the next session not a lot of work tending, lots of residual heat.  Solar electric if you can net meter is a great way to sock away the summer sun when you get there especially since solar panels are running at $0.40 a watt these days.  I would suggest you try to find a ground mounted spot for the array as the combination of removing snow and advancing age is not a great mix and the same panel will generate 20-30 percent more on the ground even without snow. Wind is an interesting beast and localized. I have not sized or sold a wind turbine since the cost of panels dropped from $5 a watt to their current lows. The tower costs kill you. Its the same economics that killed solar thermal.  As for the vertical turbines I've yet to see a commercial unit go up and post any production numbers. I could see them doing well on a windswept pasture with wind funneling on them but as soon as you throw any obstructions anywhere close the results would fall apart.  Just some thoughts. Don't get me wrong I love all of the above listed energy technologies but I'm in the position of usually having to cost these out for people so it makes me more pragmatic then most.
cheers,  David

Insulation
I like your plan of starting with insulating the buildings.

Solar
Given the price of new solar panels (about $250 per KW). Why limit yourself to just 10KW of panels for $2,500.
https://signaturesolar.com/preorder-11-47kw-pallet-aptos-370w-bifacial-solar-panel-black-up-to-480w-bifacial-gain-dna-120-bf26-370w-full-pallet-31-11-47kw-total/
Look into getting 30KW for $7,500 aka 10KW on each of the 3 buildings with south facing roof.
The railing and wires/etc will cost you an extra $1,500 for a total of $9,000

Yes you would need 3 inveters at $5,000 each  (for a total of $15,000). But it's an all in one device, so you would only have 3set of wires entering or leaving it.
https://signaturesolar.com/eg4-18kpv-hybrid-inverter-all-in-one-solar-inverter-eg4-18kpv-12lv/
It could technically be done for cheaper if we use 6 smaller inverters ($8,000 vs $15,000), with the only trade of being that it would then require a tiny bit more wiring.

I wonder what price the solar installer is quoting you?

Maybe its cheaper to do it yourself and be a "owner-builder" then just pay an electrician to connect the wires to the inverter and double check your work for a couple hundred dollars. You could get a roofing guy to help you install the railing for the solar panels too for $1,000 or so.

Some might say micro-inverters give an extra 5% efficiceny but it doesn't make sense to pay 175% more money for just a 5% increase in efficiency. I would rather get a whole other roof covered. Micro inverters do have a place esp on tinyhouse roof and small urban building, but given that you have 5 roofs that you can install more solar panels it makes sense to do a 3x bigger array. Also with this all in one inverter, you can easily install a 14KWH battery @ $3,600. 90% of the system that solar installer setup, doesn't have backup power in the event of a grid outage so do clarify/specify that with your solar installer if that is what you would like to have.

Wind
My gut reaction is that a wind turbine isn't a good fit, but I could be wrong, so here is map of the wind turbines in USA, let me know how close an existing one is to you. https://www.usgs.gov/tools/us-wind-turbine-database-uswtdb-viewer

David Baillie wrote:
John,
It sounds like you have the rough plan figured out.  A few thoughts as I read through it all
As influenced as I was with all the passive solar and thermal mass books I read from the 70's and 80's thermal mass and solar thermal simply have not panned out in our climate. Works great in higher altitude cold winter/sunny days areas but here with our 6-12 weeks of grey cold, lake effect snow its a non starter.  I totally agree that we seem to be getting more less cold but cloudy winter days than in years gone past. Insulation has proven to be the best bang for the buck... I could see someone on site suggesting a rocket mass heater/food prep bench which you fire up when you prep and coast til the next session not a lot of work tending, lots of residual heat.  Solar electric if you can net meter is a great way to sock away the summer sun when you get there especially since solar panels are running at $0.40 a watt these days.  I would suggest you try to find a ground mounted spot for the array as the combination of removing snow and advancing age is not a great mix and the same panel will generate 20-30 percent more on the ground even without snow.....

Thank you for this perspective, David...it certainly syncs with what our experience in this region has been.  It's not that passive solar provides nothing for us:  The animal facilities, to a certain extent, allow for daytime sun warming of the enclosure, but mostly just gives the critters some time in a space to feel sun for a change instead of the grey gloom characterizing so much of winter.  The sun's angle is quite low and the duration of exposure so short, however, that it does little to change the overall temperature for the buildings noted.  Nevertheless, even in our home, an old farmhouse with few windows when purchased, now has more south-facing windows and on good sunny days these assist in keeping the furnace thermostat off for longer periods than on the grey days.

One question:  Could you please explain the idea behind "...the same panel will generate 20-30 percent more on the ground even without snow."?    Why is this so?  What is it about roof vs ground mounting that would result in such a difference?

S Bengi wrote:.....
I wonder what price the solar installer is quoting you?
Some might say micro-inverters give an extra 5% efficiceny but it doesn't make sense to pay 175% more money for just a 5% increase in efficiency. I would rather get a whole other roof covered. Micro inverters do have a place esp on tinyhouse roof and small urban building, but given that you have 5 roofs that you can install more solar panels it makes sense to do a 3x bigger array. Also with this all in one inverter, you can easily install a 14KWH battery @ $3,600. 90% of the system that solar installer setup, doesn't have backup power in the event of a grid outage so do clarify/specify that with your solar installer if that is what you would like to have.
Wind
My gut reaction is that a wind turbine isn't a good fit, but I could be wrong, so here is map of the wind turbines in USA, let me know how close an existing one is to you. https://www.usgs.gov/tools/us-wind-turbine-database-uswtdb-viewer

Certainly at this point I'm less inclined to deploy wind-power unless something arises that would end up reducing our turbulence or significantly decreasing purchase and installation costs.  As the map below, derived from your link above, shows we are in a reasonably good region for wind.  The clustering of turbines to the eastern side of the map is due to hills that rise off of a very flat plain.

The installer with whom I've spoken I have a good 'feel' for....like some others here, he's been in solar and wind for a long time and was installing both in California since the late 1970s through the 1980s.  The advantage of having him on-site was that he, too, suggested the possibility of (a) ground mount vs. rooftop mount, (b) possibly switching away from the quoted microinverters and instead going with systems from Sol-Ark and/or Tigo for being able to implement battery back-up and retain more flexibility/modularity in system expansion.  My reasons for leaning into a full professional install, even with the price hit likely to accompany the choice, is that at my more senior age, current personal energy/health, and physical ability to assist on such a project dropping annually, I'd rather have something up and running soon so that we can get some benefit with the current incentives at hand.  For this reason, rather than adding more panels/capacity with my own labor, I would prefer to reduce the number of panels quoted and concordantly reduce the loads of  the property to match....at least as well as possible.....and engage an experienced installer on the project.  Battery back-up is desirable, but creates issues of its own as we likely would need to create a separate, temperature-controlled space in which to house them.  Not out of the question down the road, but not going to happen in the first install.  In the meantime, for the few power outages that we experience with our electrical cooperative, I'm content to use a generator-on-transfer-switch to provide what we need in those short episodes.

Please let me know if I've missed something or left questions un-answered and I welcome more comments as insights from you guys and others as they arise.  Thanks much for your views here!

C. Letellier wrote:Can you shave needs off in other ways before worrying about the PV part...... Roughly 50% to 70% of your household needs are thermal in heating, cooling, domestic hot water.  

Hot water being looked into....current hot water heater purchased in 1997 and rusty and poorly insulated and needing replacement.  We recently shifted from fuel oil to propane for home heating.  Maybe propane line could be added for on-demand hot water?

C. Letellier wrote:
...... Most of the year the house will almost maintain by simply opening windows and cooling off at night and closing up tight for the day.  Gets too warm late in the day and into the evening.  But cooking/canning wrecks that and we have 2 to 6 weeks where it typically doesn't cool off enough at night to cool the house off.

Any chance of creating/building an outdoor canning station that might double for meal prep during those days?  Also, I find solar cooking can go a long way with meals during peak sun/heat times of year.  Since the lack of brutal winter cold is absent during the summer, we tend to get more flexible with sleeping arrangements and just find the coolest parts of the house for night.  Have resorted to the basement at times when desperate.

C. Letellier wrote:

....It will not be the 65 degree summer day, 75 degree winter day locked temperature most people seem to want any more.

We keep our home at 60F in the winter and 'anything goes' in the summer (no A/C).  Ceiling fans and 'personal adaptation' are under-rated, but speaking from a region that only sees 100F infrequently.  Can certainly understand needing more where temps can get life-threatening.

One question:  Could you please explain the idea behind "...the same panel will generate 20-30 percent more on the ground even without snow."?    Why is this so?  What is it about roof vs ground mounting that would result in such a difference?

To put it very simply when the solar panels are mounted on a roof the generated heat does not dissipate as well as when they have an open back as they do on a ground mount. Then you have the newer panels which can absorb energy from reflected light adding 10 percent yield. Next would be in the snowbelt roof mounted panels at 30 degrees tend to hold snow cutting down production. Finally where I am here you need a structural engineer to evaluate, draw and approve you roof for solar panels and a seperate municipal permit adding costs to the project.
Cheers,  David

David Baillie wrote:
One question:  Could you please explain the idea behind "...the same panel will generate 20-30 percent more on the ground even without snow."?    Why is this so?  What is it about roof vs ground mounting that would result in such a difference?

To put it very simply when the solar panels are mounted on a roof the generated heat does not dissipate as well as when they have an open back as they do on a ground mount. Then you have the newer panels which can absorb energy from reflected light adding 10 percent yield. Next would be in the snowbelt roof mounted panels at 30 degrees tend to hold snow cutting down production. Finally where I am here you need a structural engineer to evaluate, draw and approve you roof for solar panels and a seperate municipal permit adding costs to the project.
Cheers,  David

Thanks again, David!

So just pushing some numbers on some solar sites, at a location latitude of ~46 degrees north and subtracting 2.5 degrees from this to obtain the 'year-round' best solar angle ( https://www.solartap.com/blogs/solar-101/solar-panel-angle-calculator ) for the panels, that would give me a panel angle of ~43.5 degrees...not far off of a 45 degree slope, which *may* shed snow better than 30 degrees...??  [Our home roof is ~ 45 degrees and is a metal roof....sheds snow well enough to have destroyed our gutters within the first few years of installation :-( , but still can hold some snow under the right conditions.]  I think the quotation from the installer included bracketing that would tilt the upper edges of each panel away from the roof (garage roof being a 4/12 pitch.... ~ 18.4 degrees), so with bi-facial panels may (a) collect extra reflected radiation off of the white roof and (b) reduce panel heating since they would not be flush with the roof itself.  But also to acknowledge that perhaps the "year-round optimum" angle may actually rob a system of *summer optimum*.....the season where you hope to gain as much as possible even if sacrificing some winter watt production.

To clarify, I'm already anticipating possibly going with fewer panels which would provide a bit more open spacing between bracket/panel combinations.  Also to note that I'm personally not averse to ground-mounted panels....it just falls into the category of spousal compromise on location of things on the property.  Your mentioning of permitting also is noted even though we are very rural....we've dealt with the county much on past projects and their arms have a long reach!  Grid tie expense with the rural power coop is running ~$1,200 USD and we are a net metering state (for now!) by law.

John Weiland wrote:

David Baillie wrote:
One question:  Could you please explain the idea behind "...the same panel will generate 20-30 percent more on the ground even without snow."?    Why is this so?  What is it about roof vs ground mounting that would result in such a difference?

To put it very simply when the solar panels are mounted on a roof the generated heat does not dissipate as well as when they have an open back as they do on a ground mount. Then you have the newer panels which can absorb energy from reflected light adding 10 percent yield. Next would be in the snowbelt roof mounted panels at 30 degrees tend to hold snow cutting down production. Finally where I am here you need a structural engineer to evaluate, draw and approve you roof for solar panels and a seperate municipal permit adding costs to the project.
Cheers,  David

Thanks again, David!

So just pushing some numbers on some solar sites, at a location latitude of ~46 degrees north and subtracting 2.5 degrees from this to obtain the 'year-round' best solar angle ( https://www.solartap.com/blogs/solar-101/solar-panel-angle-calculator ) for the panels, that would give me a panel angle of ~43.5 degrees...not far off of a 45 degree slope, which *may* shed snow better than 30 degrees...??  [Our home roof is ~ 45 degrees and is a metal roof....sheds snow well enough to have destroyed our gutters within the first few years of installation :-( , but still can hold some snow under the right conditions.]  I think the quotation from the installer included bracketing that would tilt the upper edges of each panel away from the roof (garage roof being a 4/12 pitch.... ~ 18.4 degrees), so with bi-facial panels may (a) collect extra reflected radiation off of the white roof and (b) reduce panel heating since they would not be flush with the roof itself.  But also to acknowledge that perhaps the "year-round optimum" angle may actually rob a system of *summer optimum*.....the season where you hope to gain as much as possible even if sacrificing some winter watt production.

To clarify, I'm already anticipating possibly going with fewer panels which would provide a bit more open spacing between bracket/panel combinations.  Also to note that I'm personally not averse to ground-mounted panels....it just falls into the category of spousal compromise on location of things on the property.  Your mentioning of permitting also is noted even though we are very rural....we've dealt with the county much on past projects and their arms have a long reach!  Grid tie expense with the rural power coop is running ~$1,200 USD and we are a net metering state (for now!) by law.

Spousal buy is a critical variable that beats peak efficiency every time!!!  It sound like you have all your ducks lined up. I would council against extra spacing on the panels as any gain you might achieve on overheating would be negated by the creation of more crevices and bumps to allow the snow to hold. I have thought that if I do a roof mount for someone again I would employ something like this: https://www.greenbuildermedia.com/blog/remote-control-snow-melting-for-rooftop-solar
Basically heat wire under the panels to create a melt layer that would slide off. It might work great for your 45 degree angle.
CHeers, and good luck
David