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What renewable energy source to go with?

Rtk2 | Posted in Green Building Techniques on

Hi, I’m new here. Glad I found this place. 

I am currently building a home and I’d like to install a renewable energy source. There is so much informantion and I’m just overwhelmed. 

I am building in northern Michigan, and I’m most concerned with heating and cooling. For heat, I am going to use am wood burning stove. But for cooling, I’d like to know the best value option to cool my house with renewable energy. 

I have looked at the options but have some questions below about each one:

SOLAR PANEL: Is  a solar panel system ann option for me in northern Michigan? Is there enough sunlight? I am looking at some DIY systems. 

GEOTHERMAL: I thought about this option because it heats and cools, and I believe I can install this myself or with a little help. I also will have a well, and I’ve read i can run the pipes into that or connect it to the well…? Isn’t that right?  I know it can be done thay way. Only think that got me thinking about other forms rather than GeoThermal is if i purchase a Solar or Wind Turbine it couldnt potential run the whole house electricity, whereas GeoThermal is just heating and cooling. So, if its around the same cost for geothermal as wind or solar, I’d probably be better of with solar or wind id think…..or no?

WIND Turbine: would this be a good option in northern Michigan over solar because of a potential lack of sunlight for solar? Is it a better option than Geothermal?

I am not looking to spend a crazy amount of money. I want good value, and installing any of these products is not an issue for me. I am a DIYER that just wants to save as much on electricity and heating and cooling as I can. 

Also, would it be a good option, because of the lower cost, if I just went ahead and installed a wind turbine  or solar panel system that is capable of running just my AC? 

I want to thank in advance anyone that can help me out. I know i listed a lot of stuff and questions, but it’s really only one question:

What is the best option for me with cost taken into consideration?

I’m mostly concerned with cooling my house in the summer, but I don’t want to waste money on one option if there is a better option that doesn’t cost as much and it offers much more than just cooling my house. For example: I don’t want to spend on geothermal if wind or solar is about the same cost and csn run my whole house, in addition to cooling my house. And since I’m mainly worried about cooling, would it be better just to install something to cool my house rather than install something to run all electricity in my house, because that would be cheaper….

And I’m not opposed to having soemthing run my heating either if it goes with whatever is suggested to cool my house. 

Thanks for the help. I’m confused.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    RTK,
    First of all, can you tell us your name? (I'm Martin.)

    1. Wind energy is not cost-effective on a residential scale. For more information, see "Resisting the Allure of Small Wind Turbines."

    2. The type of heating and cooling system that some people call "geothermal" is more accurately called a ground-source heat pump. A ground-source heat pump is not a renewable energy system. It is a heat pump, just like the heat pump in your refrigerator or any common air conditioner, and it requires electricity to run. In most cases, a ground-source heat pump is not cost-effective on a residential (single-family) scale; rather than installing a ground-source heat pump, it makes more sense to install an air-source heat pump (for example, a ductless minisplit).

    For more information on this topic, see "Are Affordable Ground-Source Heat Pumps On the Horizon?"

    3. A photovoltaic system (sometimes called a solar electric system) may make economic sense, but only if your local electric utility offers a good net-metering contract. You should call up your local electric utility and find out what the company offers. For more information, see "An Introduction to Photovoltaic Systems."

    People in cold, cloudy places like northern Michigan have success with PV. (Germany is quite cloudy, but lots of PV systems have been installed in Germany.)

  2. GBA Editor
    Peter Yost | | #2

    A good resource for learning about financial support available to you for renewables and efficiency is the Database of State Incentives for Renewables and Efficiency:

    http://www.dsireusa.org

    Peter

  3. Jon R | | #3

    Having a well helps the economics of ground source heat pumps. But viability depends on water quality (eg, hard water used for cooling will require excessive amounts of heat exchanger cleaning).

    Keep in mind that with enough insulation and air sealing, very little cooling will be needed.

  4. Expert Member
    Dana Dorsett | | #4

    Even further out in Da Yoop the only non-combustion renewable energy SOURCE that has any economics at small scale is solar. On an annual basis it will still deliver more than half what they get out of it in the sunny southwestern states.

    https://www.nrel.gov/gis/assets/pdfs/solar_dni_2018_01.pdf

    Also the economics of ground source heat pumps are very site and region specific. It's often the case that going with cold-climate air source heat pumps and a bit more solar is a better investment. There are several ductless and ducted air source heat pumps with a specified output at -13F /-25C and a bit colder.

    But until you have calculated the heating and cooling loads it's premature to be specifying the equipment type and model.

    To minimize cooling loads, minimize the amount of east and particularly west facing window area, and use deep overhangs on the south facing windows to limit the summertime sun. Tuning the low-E coating types of the east and west facing windows to be heat rejecting types will help too, but it's primarily about window area. It's difficult to adequately shade west facing windows due to the lower afternoon/evening sun angles, and they take their solar gain late in the day when the outdoor temps are warmer, and the house has been soaking up sun all day.

    If it's not too late to tweak the design of the house, take a look at the "whole assembly R" values in the zone 6 & 7 rows 0f Table 2, p10 of this document:

    https://buildingscience.com/sites/default/files/migrate/pdf/BA-1005_High%20R-Value_Walls_Case_Study.pdf

    Northern MI is zone 6, the UP is mostly zone 7, but the middle part is zone 6.

    Those numbers are the approximate limits of what is financially rational on a lifecycle basis. It also happens to be roughly what it takes to hit Net Zero Energy on an annual basis with a PV array that fits comfortably on the house. (This was by coincidence, not design.) In the decade since that was written the efficiency of rooftop solar has gone up, and the cost has fallen by more than 2/3, and with a careful design it's possible to hit Net Zero at the values a full row number lower than what's in that table.

    So if you're in DOE climate zone 6 you might consider row 5 as reasonable starting point. The numbers are "whole assembly R", that takes into account the thermal bridging of the framing, as well as the R values of all layers, not just the insulation (eg wallboard, sheathing, siding, interior & exterior air films, etc.). With typical siding and finish options a 2x6 wall with R20 cavity fill comes in at about R16-R17, but sometimes only R15 if the framing is dense, or R18 if it's 24" o.c. with single top plates & window headers, a minimum of doubled-up framing. Going with R23 rock wool instead of R20 fiberglass in the cavites adds about R1 to the whole-wall number. To hit the R30 range with that structural wall would take 2-3" of exterior polyiso foam board.

  5. Scott Wilson | | #5

    With your primary concern being cooling the house in the summer you should look into including high clerestory windows on the north side of the house. They can be designed to have battery operated window openers on them so that when the house starts to get hot you open the clerestories and create a natural thermo-syphon effect across the house. Cool air enters through a low opening window on the shaded south side and rises across the house and exits on the high north side.

    You could also consider using a DC ceiling fan in the main rooms.

  6. Rtk2 | | #6

    Wow. Lots of information here. Thanks guys.

    To answer some questions: My name is Ryan. Thanks for asking.

    I guess I've learned that most here think solar would be the way to go over geothermal or a wind turbine.

    Is that correct?

    I just see a lot of people installing the geothermal heat pumps by themselves to substantially lower the cost. Does this make it a more viable option. My house is also going to be built off a canal. Does that help or no?

    Also, I see some wind turbines on ebay that dont seem that high of a cost. Seems I can get a 10kw wind turbine for around $5,000.

    I will be installing whichever I energy I choose myself. Whether it's wind, solar, or geothermal. So, will that make any difference in which to go with?

    If I install solar, will I see any benefit from it in utter he cloudy winter months of Northern Michigan. If it doesn't offer me much in the winter, would I be better off installing a smaller scale solar panel system to just run my air conditioning?

    I am in zone 6. Forgot to mention that.

    I want to thank you guys a lot. I'm gonna read everything that is posted on this board and in the links.

    Thanks a ton!

    1. Bill Dietze | | #12

      Ryan, just to reiterate what Martin said. If you are looking for a source of energy for on-site generation, and since you have net metering, solar is the only real option for you. Geothermal is not an energy source. In your case I assume you have no source of magma heated rock under your house, so for you 'geothermal' simply means a heat pump. Those consume energy, they do not generate it.

      If you want a heat pump to pair with your PV array, then you should very seriously consider minisplit heat pumps. If you are determined you can DYI one or two of those and they can work great in zone 6.

      GBA is full of posts from folks in cold climates who are satisfied with their minisplits. Remember that the ground source heat pump option always ends up as a custom installation. I'm in zone6/7 and have two single head minisplits, one on the main floor and one in the walk out basement with cove heaters as backup/supplemental heat for the corner rooms. The performance matched what I expected with no surprising quirks.

      1. Jon R | | #15

        > Geothermal is not an energy source.

        Technically it is. So is the air (in the case of an air source heat pump). But it doesn't matter - you want to consider all the options (insulation, PV solar, geo, air source, house size, windows) and pick the most optimal mix.

  7. Rtk2 | | #7

    Oh, and thanks for the link on state info.

    My area offers net metering. That is a plus. So, maybe that makes solar a better option?

  8. Expert Member
    Zephyr7 | | #8

    Net metering effectively eliminates the need for storage batteries on a solar setup. The battery setup is probably the second biggest cost after the PV panels themselves, and the batteries are the biggest maintenance item in the system too. With net metering, you sell your excess solar energy production to the utility during the day, and you buy power from the utility at night and on cloudy days or anytime your electric demand exceeds the capacity of your solar system. The utility essentially acts as your battery.

    This isn’t always a great deal for the utility, but it is a VERY good deal for people with grid-connected solar systems.

    Bill

  9. thrifttrust | | #9

    Before you consider any of these options you should put your energy and treasure into insulation and air sealing your new home. Your next decision will be how to ventilate. The result will affect how much cooling you will need, the size of your wood stove and how you will provide combustion air to it. If the house is in the planning stage and you are thinking of rooftop solar you should make sure to have enough unshaded south facing roof. The ideal pitch for Michigan is 10" in 12", about 40°

    If you go with solar there are reasons for urgency. After 2019 the federal solar tax credit is reduced and will be eliminated a few years later, but more importantly the Michigan electric utilities have filed with the state regulators to eliminate their net metering programs. They haven't said how much they will cut their payments for excess solar power, but they did say they will grandfather existing solar installations, allowing them to keep their net metering deals for ten years. They plan to begin the new regime sometime in 2019. Regardless, you have to get permission from the electric utility. They want a detailed description of your planned installation, They want to know the brands of panels and inverters you will use and their UL certifications. They want to know how much electricity your system will produce and proof that you can use it. The process can take a couple months. The online application has a handy-dandy calculator that uses manufacturer published specifications, (selected from dropdown lists of hundreds of panels and inverters), array orientation, shading and climate to determine annual solar production. For point of reference, my 10KW system in Detroit, with near ideal situation, (south facing, 40° tilt, 12% shading) came out to about 10,000 KWH annually according to the calculator.

    Douglas Higden

  10. Walter Ahlgrim | | #10

    How many day a year do you have over 90°, I am guessing 8 can you tuff it out? That would be the greenest option.

    Solar wind and geothermal are not DIY friendly and craze money.

    Walta

  11. Expert Member
    Dana Dorsett | | #11

    >"I just see a lot of people installing the geothermal heat pumps by themselves to substantially lower the cost. Does this make it a more viable option. My house is also going to be built off a canal. Does that help or no?"

    If you are allowed to draw from and discharge water to that canal, or install a huge slinky of plastic pipe in the canal it can be a lot cheaper than drilling wells, so yes, it can help.

    But is the water-to-water heat pump or water to air heat pump with a big pond/canal loop more cost effective than a cold climate air source heat pump plus a few more solar panels to make up the difference in energy use? Sometimes, but not usually.

    It's still a better investment to go quite a bit better than code on insulation and windows than spending it on ever higher efficiency heat pumps. Cold climate mini-splits are pretty efficient and low maintenance for the money, and easier to design around.

    >"Also, I see some wind turbines on ebay that dont seem that high of a cost. Seems I can get a 10kw wind turbine for around $5,000."

    A 10kw wind turbine that doesn't have access to sufficient wind is just a $5000 house ornament. Doing a wind survey and siting for a small turbine takes time, and unless you're on a favorable lakefront bluff or cliff you probably don't have sufficient wind resource to make it a better investment than $5000 of solar panel. A 10kw wind turbine that averages 100-500 watts of output in your location isn't worth five grand. Solar surveys are much simpler and more predictable.

  12. GBA Editor
    Martin Holladay | | #13

    Ryan,
    At the risk of repeating what others have said, here's some advice: Take a step back.

    You're probably asking the wrong question. You don't really need to invest in expensive equipment to make your own energy. That approach is rarely environmentally sound.

    What you really want to do is find ways to use less energy in the first place. The means building a small, energy-efficient house. It's OK to buy your electricity from the local utility. Just use as little electricity as possible.

    Paying attention to transportation also makes sense. If you care about the environment, it might make sense to live in town, near a bus stop or withing bicycling distance to stores.

  13. Stephen Sheehy | | #14

    Ryan - small wind turbines are almost never cost effective. You can't attach it to your house, because the vibration will be awful. So you need a very tall tower, attached to the ground with a lot of very sturdy anchoring points. Picture a big sailboat mast, with shrouds attached from the top of the mast and at intermediate points, all running through the deck and attached to robust chain plates bolted to the hull.
    Then consider that you'll need to hire a crane to do any repairs or maintenance, since the generator is on the top. ( a lift won't get tall enough.) After all that, you'll never get 10 kw unless it's really tall, there are no trees anywhere nearby and you live in an extremely windy location.

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