We are in the design stages of a new build of 3600 sq ft, after our home was destroyed by fire.  I am very interested in building as green as possible.  We are located in central California where Summer temps are routinely over 100 degrees and the rear of our house would be facing West so I thought it would make a good solar candidate.  We visited
our local solar dealer/installer and he proceeded to tell us that with the new building technologies making homes more energy efficient and "airtight", that we really wouldn't need solar.  Not sure why he would talk himself out of a job, but this has further confused us.  How would one find out if solar is really beneficial to their situation?

Thanks for any input,

Theresa

If you are interested in solar and you are still designing, you should consider orienting the house and exposure Solar south, not west for higher performance.

I would  think solar hot water (DHW) heating would be cost efective if done properly. As far a solar PV, that depends on many factors.  I would consult a few more installers. 

Eric

Super-insulation techniques, framing with thermal breaks, and carefully controlling the siting, size, type, & orientation of glazing, and providing for sufficient thermal mass to handle daily temp swings can make a central CA house into a near-zero heating/cooling energy house. The average January temps in say Sacramento are 45F, which isn't much of a heat load if you have R30+ clear-wall values and limit the total glazed area. A modest amount of high-gain S-facing windows could supply a large fraction of the load.

Average temps in July/August in Sacramento are in the mid-70s, which isn't much of a cooling load, and it's dry enough to use high thermal mass and a nighttime ventilation scheme to handle the bulk of the cooling, provided you limit the solar gain, and have R60+ attic insulation, a decent pitch to the roof, and use cool-roofing material. A large array of west-facing windows would be a disaster from a cooling load point of view, even if it worked out well during the heating season, since the summertime gain would be huge. Operable exterior shades, plantings & awnings can work well for killing summertime solar gains. Solar hot water or PV could work just fine on a west facing roof pitch though.

The PassivHaus Institute tools were created for designing house with minimal heating & cooling loads. It's probably worth analyzing & tweaking your design with their tools. You can buy a LOT of insulation for the money it costs for sufficient solar to heat/cool an un-optimized building envelope.

Hmmm, not sure why the edit to hyper link it shows up as a double-post, (oh well...)

Air-tightness is job-1 for high-efficiency buildings, then insulation. High efficiency mechanicals or solar come well down the cost-effectiveness tree. Much of CA is amenable to Passive House techniques for achieving near-zero heating/cooling requirements without resorting to super-high R values. You might poke around passivehouseca.org (run by a group of SF bay design pros) for design ideas/help. Nahib Tahan is an architect who has pulled off at least one successful remodel in Berkeley upgrading an antique bungalow to PassiveHouse standards. (Google him. Home Energy mag did a short article detailing that project a couple of years ago.)

Oops! Make that Nabih (not Nahib) Tahan. 

His website lives here.  

The Home Energy article on his Berkeley project lives here.

Thank you for the EXCELLENT information here.

Theresa

Theresa, I would definitely try to get the opinion of more than just that one installer. As with many things in life, second opinions are generally the best way to go and get input from multiple sources. Not sure why he would talk himself out of a job either, but even with advances in energy efficient windows, doors, and other features there is still energy consumption in your new home! Agree that if you can get your home orientated South before you start building it would be best. If the design and building have already began, though, you can still work with a home facing other directions! Good luck with the construction and solar!!

If the solar company has evaluated your site, he or she may have noticed solar access problems. Find solar or true south and find see if you have unshaded access throughout the year. Any investment in solar equipment should be oriented to true south. If you must, you can be plus or minus 15 degrees from true south and lower efficiencies by 10%---but why?
Energy conservation first, correct glazing,shading and thermal mass next and then look at supplementing the balance with active solar.