How can the mounting hardware cost as much as the panels? How do you work around it?

GmonroeGmonroe Registered Users Posts: 8
I've been trying to come up with the ultimate, optimal design for an energy efficient house. While location, climate, and desired architecture are all factors some designs are probably optimal if you simply focus on efficiency.

First, insulation :
These concrete geodesic domes with R-36 foam all around are probably close to the most efficient choice for structure available. Underground houses and ones built in dirt might be more efficient, but those are site-specific. (so are these, I suppose - got to get the locals to sign off on one). I'm thinking a house built from a single dome (a separate one for the garage) with a few sealed skylights. Most windows would be non-operable, conservative in size with careful placement, with double or triple paned glass. Built right, this place would be insulated significantly better than most freezers.

Well, if you start with one of these I'm wondering how to mount the PV array. None of the faces point precisely the same way. A second factor is that you need occasional access to the surface of the dome to repaint it, an every 5-7 year project. (one of the few maintainence tasks this type of structure needs, they are supposed to be maintainence free in most other respects).

Poles would work, but they are rather pricy. A 3000 square foot home would need at least 3 of these systems : http://sunelec.com/index.php?main_page=pv_systems&id=1050&type=GT

To mount all those panels on poles (the base of each pole would fit into a mount that would be either bolted to the dome or to the ground) would cost about $13,000. That's half the price of the rest of the system! It might actually be a better idea to buy more expensive and more efficient panels just to get the same output using fewer panels and/or expensive mountings.

At these prices, are sun trackers even worth bothering with? If the bare panels cost this much, I shudder to think of the cost (and maintainence requirements) of a big electric motor/sensor system to move the array every day.


Another thing I wonder about is how multiple systems fit in. For this "ultimate efficiency structure" it would use an indirect solar hot water system, fed by both a rooftop box with the piping AND a desuperheater off of a geothermal system. And what the heck, might as well add in a drain heat recovery system and use a gas fired on demand heater as the last stage of the heater. That's 4 different systems just to heat up water. The cost of each additional system might not be worth the dimishing payoff. Just a gas fired on demand heater boosts efficiency by ~19% compared to a tank system. Drain heat recovery supposedly recovers about 50% of the heat. At that point it's probably not worth the cost to add a solar system and the desuperheater.

Similar arguments apply as to whether it's worth it to use geothermal heat and A/C for a dome when heating and A/C demands are so low anyway. You'd need a smaller geothermal system for a dome than a conventional structure but there's fixed costs in drilling the wells for a system. (though the kind that use trenches are probably not too unreasonable in cost. A DIY kit is about 5 grand)

My thinking is unclear, here. Now that I look at these words, I realize that I'm not trying to envision the most energy efficient structure possible - I'm trying to factor in economics as well. Alas, if I think about it too much, I realize that the most energy efficient and economical structure is an apartment in a beehive. Shared walls, ceilings, floors - can't beat that reclaimed energy with fancy tech.

Comments

  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    Couple of points.

    You might consider a ground mount.

    Second, IMHO the concept of domes is pretty good, I have know several people who have lived in them, and they were very difficult houses to live in in any conventional ways. A well designed passive solar house of more conventional style might be easier to facilitate both PV and hot water.

    Remember, my opinions on subjects such as this are worth exactly what you pay for them. good luck and keep. In touch. And welcome to the forum.

    Tony
  • GmonroeGmonroe Registered Users Posts: 8
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    What are some of the things that go wrong with domes?
  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    its not so much as what goes wrong with domes its a lot about nothing fits.. you have a lot of wasted space.even a tall refrigerator takes up about 1/3 more floor space. its things like that that create bad use of space, things just naturally fit better into rectangles or squares..
    I have a friend that had one . he sold it , it seemed like a good idea at the time he built it(it was mostly concrete) but it was hard to use the space in it.
  • GmonroeGmonroe Registered Users Posts: 8
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    To me that sounds like a solvable problem. The type of dome I linked doesn't have that height problem on the first floor (it has these walls that elevate the base a few feet vertically), and storage and utility stuff and cleverly made rooms can be put on the second floor around the edges.
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    What John P says X 2. Way more volume, hard to manage interior and exterior wall space and they are a pain to do finsih work, in due to off angle ever where.

    If the dome you linked "doesn't have the problem on the first floor, my guess is that you have a ton of heated volume that is potentially wasted.

    Two of the dome owners that I have know hav torn the down.

    T
  • BB.BB. Super Moderators, Administrators Posts: 32,019 admin
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    I don't know about dome specifically, but many "unusual homes" also end up with unusual problems...

    As above, many round/spherical homes end up with problems of efficient use of space.

    Another one is sealing against rain water. There is a local home known as "The Flintstone House" made from gunite (sprayed concrete). It had terrible water leak problems until they coated it inside and out with urethane resins.

    The neighbors also have hated the home for better than 3 decades now. :roll:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    as others have said just ground mount it.
    easternmetal.com will wholesale alluminum to you
    it is much cheaper to use prefab aluminum then by expensive name brand extrusions.
    8020.net on ebay is also good.
  • PhotowhitPhotowhit Solar Expert Posts: 5,658 ✭✭✭✭✭
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    I will add mine to the masses, about reconsidering a dome, lived in one a short while, really an octaganal with pie shaped rooms, made for wasted space corners and rooms that seamed tiny since the corners didn't get used other than storing dust bunnies, or a round wasted bin or leaners, bows, brooms, cue cases,...

    Can't imagine the roof closing in on me too! I'll have nightmares....
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • SCharlesSCharles Solar Expert Posts: 123 ✭✭
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    The house I built has two octagonal rooms. These are two of the main rooms: kitchen and living room. I was inspired, back then, by yurts and domes. So, they are roundish. They are very pleasant to sit in. However, as others have said, furniture and appliances, for one, are designed for squared-off walls. Some of that is practical, of course [not much use for some odd-shaped 'fridge].

    We have to carefully consider the item when we decide we need a new couch, for example. Our living room is 175 sq. ft or so. That isn't tiny. But each interior wall is a bit less than six feet across. This greatly limits the size of couch. Plus, arranging the items in the room is wasteful of floor space: one easy chair along one wall and there is room for a reading lamp but that's it.

    I really like my home. However, were I to do it again, I would either forgo the cool roundish shape of those two rooms or make them larger to begin with.

    As for mounting pv panels on a dome or other unusual roof, it will be a big-time hassle. There is no way to orient them efficiently or to work on the roof easily. My array is built for ground-mount and the racks are made of 1.5" angle iron. Relatively inexpensive [I say again, relatively], easy to weld up. I paint them with good paint and predrill holes for the bolts I use to secure the panels.

    My first rack of panels was on the roof of the house. I came to needing new roofing, the rack had to come down. Of course, this meant disassembling everything, no way to carry a rack full of panels and wires down a ladder or whatever. I opted at that point to set them up on the ground and I am very glad I did. I mounted them on the roof initially to keep wire runs shorter and security [theft] higher. It was well worth springing for some larger ga. wire to have them on the ground, simple for me to clean and sweep off snow and check now and then.
  • SolarLurkerSolarLurker Solar Expert Posts: 122 ✭✭
    Re: How can the mounting hardware cost as much as the panels? How do you work around

    I Have been in a few dome homes, the insides are always awkward.

    Build a more conventional house with ICf's,
Sign In or Register to comment.