Passive Solar Resources

bentherebenthere Solar Expert Posts: 113 ✭✭✭

We are planning to add on to our home in about two years. Our high-desert location is perhaps perfect to take advantage of passive solar energy and I am quite interested in learning more about that. I have already increased our south glazing, added a trombe wall, replaced asphalt shingles with e-star metal, etc. and am very happy with the results thus far.

My initial experiences lead me to believe that generating enough heat will be easy. It appears the tricks will be; cost-effectiveness, summer cooling, seasonal adjustments, weather adjustments, and minimizing daily fluctuations.

I would love to share my trombe wall lessons and experience with you all, but - alas - there is no passive-solar section on this forum. Should there be?

I came across this site in my quest for passive solar ideas and information. To me, it has all the hallmarks of a scam; redundancy, blinking text, BUY NOW!, "everybody else does it wrong", etc. and yet some of the information presented seems logical and agrees with my personal experiences.

Would anyone care to validate/invalidate some of this site's claims based on their own experience or knowledge?

There has got to be a better source of information on passive solar. Does anyone have a favorite?

Thanks in advance for your thoughts.



  • mike95490mike95490 Solar Expert Posts: 9,082 ✭✭✭✭✭
    Re: Passive Solar Resources

    I doubt there is much there, that you cannot get for free elsewhere, in a less fancy package.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    gen: ,

  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Passive Solar Resources

    I think it is a fine idea,,, MODs?? Wind-sun?

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Passive Solar Resources

    My favourite is BuildItSolar:
    Just too many good ideas/projects there to keep up with!

    I agree that perhaps a section for solar thermal/passive solar might be good, as it is usually quite a separate issue from the solar electric or wind power and probably more popular/practical than micro-hydro.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Passive Solar Resources

    passive has its place and can work to a degree although i don't really have much experience with it. i don't mind if there would be a passive solar section, but would it be warranted as i suspect it won't be too big? it would be windsun's decision though.
  • bentherebenthere Solar Expert Posts: 113 ✭✭✭
    Re: Passive Solar Resources

    I didn't mean to bring this up as a request - on a holiday, no less - but I would enjoy a passive solar section on this forum.

    There definitely seems to be an interest in solar hot water which might be well-combined with a passive section. Presumably we all have at least some interest/experience with passive solar since we are all trying to conserve energy?

    I have seen and enjoyed articles at Good stuff.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Passive Solar Resources

    this is true that solar hot water has been discussed a few times just as batteries should have their own section, but fit well into the others too.
    maybe the arguments for and against the new section may help make up windsun's mind. discuss it.
  • bentherebenthere Solar Expert Posts: 113 ✭✭✭
    Re: Passive Solar Resources

    Maybe we could try it out as an authorized topic in "Energy Use and Conservation"? That seems like a reasonable fit unless it turns out to be a popular topic.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Passive Solar Resources

    it could be used in general solar topics too and i might be tempted to move any on solar hot water as they all tend to need pumped. like i said the subject can often fit more than one category that is presently in place. your job would be to convince windsun that this would warrant its own spot rather than fit into the other categories. it is after all only a general subject label.
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Passive Solar Resources

    Passive solar space and water heating historically has a bit bigger bang for the buck than PV in terms of energy saved/produced. For example a simple batch hot water heater can be built for almost nothing, needs no pump, infrastructure and little maintenance and yet will yield very useable amounts of hot water. Passive solar space heating really highlights the value of energy conservation, especially insulation, and window insulation, since glazing can lose more heat than it collects in many cases.

    Problem is it isn't very "sexy" compared to PV.

  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Passive Solar Resources

    You could find some useful info on the German "Passivhaus" building standard here:

    It uses passive solar heating as one of the heating sources, but isn't solely focussed on solar heating only, the basic premise is to build the house super-insulated and airtight and then derive heating from passive solar and from the appliances already inside - even the occupants contribute to the heat.

    It's a building standard that has been used to build thousands of houses in Germany and it's quickly becoming a popular energy efficient standard in the rest of Europe. Some of the first houses are popping up in the US too:

    One of the nicer tools is the Passivhaus planning package (PHPP) available for a hundred odd pounds which is an excel spreadsheet used to model the behaviour of, and certify the building. It has been refined over 20 years by correlating the modeling with actual houses. The modeling is highly dependent on having the correct climate data in the tool.
    (Which is also fun to play with, I can quickly see that if I built this house in Spain it would require 14kWh/square meter/year to heat. The same house in Montreal would need 74kWh/sqm/year to heat).

    Here's an excerpt of the windows section for my planned house and the overall energy gains and losses on a monthly basis.
  • bentherebenthere Solar Expert Posts: 113 ✭✭✭
    Re: Passive Solar Resources

    Thanks for the Passive House info. It looks like the standard may be taking off, and possibly provides a means to know who knows what they are doing and who doesn't.

    I'm not super-excited about building our house to a standard so much as responsible energy use and not leaving any low hanging fruit unharvested. Maybe I should be? I guess much of the benefit of a standard comes from resale value? I certainly am thankful to have a resource that offers measurable results.

    Interestingly, it was the idea shown in this picture (east shade) that got me thinking about further gains. Here the west sun is a killer and I was thinking about the cooling benefits of going beyond "Orient your rectangle house correctly."
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Passive Solar Resources

    I guess I banged on about the standard too much - what I really wanted to say was that you can use the PHPP excel spreadsheet to determine the best orientation and shading for windows, etc. A few things I learnt from it for our house:
    - Shading over south facing windows was essential to prevent overheating in summer (kinda obvious :) ).
    - Triple glazed, argon filled windows in the south wall would be _less_ efficient than double glazing even though they are better insulators because they reduced the amount of solar gain. This isn't true in more northern latitudes where the extra insulation is more important than the extra sunlight in winter.

    Another really helpful and free tool is google sketchup which will let you draw a building in 3D and then watch the sun's path and shadows throughout the year. Perfect for determining exactly how big your shade area in front of windows has to be.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,547 ✭✭✭✭✭
    Re: Passive Solar Resources

    One of the reasons I never settled where you are (came damn close) is that I was concerned with getting enough water for evaporative cooling and wood to keep warm. I knew that passive was the way to go. It is a ton of work and can be expensive.

    With the modern variable speed heat pumps (air source) now available there are easier choices. Brute force solar on multiple or tracked arrays can provide 6am to 7pm power in the summer. A well insuilated structure can be heated and hold the heat till the next day. There are options now that make less than perfect homes near passive in comfort.

    I liked the link you provided. I like the concept of not needing to do anything to be comfortable. It is also very "cool" to have a 20+ seer split heat pump cooling off-grid and hardly hear if it is running. Buenas Suete!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
    E-mail [email protected]

  • System2System2 Posts: 6,290 admin
    Re: Passive Solar Resources

    There are some very efficient Passive solar panels available. Check
  • russruss Solar Expert Posts: 593 ✭✭
    Re: Passive Solar Resources

    About North Point Solar,

    The concept is fine - you need a fan to make it work which they kind of say.

    Very few details except 'call us' on their web site.

    The construction is mainly wood - not bad but not the best for a long life. Details of the whole thing are too skimpy.

    When a company puts few details like this one does and says call us I tend to worry about why they can not be more forth coming.

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