For an architect who is supposed to be helping people build solar-heated houses, Malcolm Wells asks an awful lot of personal questions - such as:

"Do you own an electric can opener?

"What do you do with your old newspapers?

"When was the last time you defrosted your refrigerator?"

It's not that Wells considers everyone who owns an electric can opener to be an ecological outlaw, but he belives people's lifestyles reveal something. Someone who insists on an energy-consuming appliance to open every tin can, or who isn't into conservation enough to recycle newspapers, probably isn't ready for solar heating. Ditto for dilettantes who don't recognize that frost-choked freezers waste electricity. Wells practices the kind of earnest energy-awareness that places moral value on taking fewer baths or cold showers to save water and energy.

For anybody that concerned about conservation, or at least anyone concerned enough to contemplate solar heating, Wells has written a book, aided by Irwin Spetgang, his partner, engineer and business manager.

How to Buy Solar Heating . . . Without Getting Burn! (Rodale Press, 262 pages) may be one of the best $6.95 investments in solar heating a homeowner can make.

Wells and Spetgang have written a primer on solar systems that is an advanced text on the dollars and details of being the first on the block with a solar-heated home.

In Washington recently to promote How to Buy, Wells must have given his agent fits when he told people his book isn't the first one a solar neophyte should get.

Start with The Solar Home Book, by Bruce Anderson (Cheshire BOoks, $7.50), he suggests, to learn the basics. Then when you're serious, get mine. For the types who want to engineer their own solar heating system, Wells earlier wrote Your Home's Solar Potential (Edmund Scientific, $4.95), a pencil-and-paper workbook for percisely calculating the solar suitability of a house.

That's probably too technical for many homeowners, acknowledged Wells, who repeats the advice of one satisfied solar pioneer, "It's terribly important that we not be overwhelmed by the look of what is basically a very straightforward technology."

As a solar architect, Wells is best know for the house called Solaria that he designed for Bob and Nancy Homan of Indian Mills, N.J. Solaria is in all the solar house books and uses collectors designed by Harry Thomason, Washington's solar pioneer. Water trickles down the corrugated panels, is warmed by the sun, then stored in a big tank and used to warm the house.

It's a simple - some say unsophisticated - design, and Wells says that's why it works. With objectivity rare among solar advocates, the book quotes the owner of a similiar system as warning however, that "trickle systems are notorious leakers."

Though they might have asked for more detailed diagnosises, Wells and Spetgang questioned every solar homeowner they could find about the problems of sun power. The result is an atlas of roadblocks:

Not enough sun - due to climate or lack of southern exposure - and not enough insulation - leaking away heat faster than its collected - are the biggest problems predicted by the authors, but the solar homeowners were most troubled by costs.

"Our $10,000 solar system ended up costing $16,000" lamented one solar pioneer. "The contractor was learning at our expense, paying high-priced plumbers." Our cost doubled, and we couldn't do anything about it."

Then there are delays - solar projects are never finished on time - and leaks. The kind of solar heating systems that use water are more prone to leak than those that use air, but even passive solar houses, with no moving parts, can leak, the homeowners warned.

Add to the list design flaws, overly complicated controls, faulty equipment and materials, improper installation, and inexperienced contractors and you understand why Wells and Spetgang put their solar homeowners poll in the back half of the book. The people who live in glass-walled house also warn that solar homes draw gawkers, as well as goats, which one homeowner found tried to eat his collectors. And falling off the roof of a solar heated house is as easy as, Well . . .

Drawing on their experince as architects and builders, Wells and Spetgang provide model contracts specially tailered for solar projects and speel out in more detail than contractors will appreciate how to handle the contingencies that arise when an uneducated homeowner hires an untrained builder to do an unfamiliar job.

There's also a good introduction to sun rights and solar law. If you build a solar house, and your neighbor decides to pur on an addition that blocks the sun, there's not much you can do, the book admits. And if the glare off your collector shines in your neighbor's dinning room? Remember that justice is not blinded by the sun in her eyes.