IRAN, HARRISBURG and gas lines - these have impelled some fast movement in thinking about energy. Rhetoric aside, conservation and solar are being propelled forward by a logic - a logic of necessity. The pieces of the energy puzzle look to end up arranged quite differently from what most anybody expected after the 1973 embargo.

Now, more or less at the right time, a powerful new case is made for solar energy by Barry Commoner. The book has a great deal of merit and will advance the energy dialogue - in so far as solar is concerned. Unhappily, the merit, like oil-bearing structures in the earth's crust, is not evenly distributed throughout the book.

The great strength of The Politics of Energy is its effort to lay out a solar future - and a reasonable future it is. Commoner knows that projecting is a risky business, but he does it in a very useful way.

"There is," he writes, "no solar panacea. No one solar process can efficiently produce energy in all parts of the country. A national solar-energy gathering system needs to be as varied as the country itself, reflecting its uneven climate, terrain, and vegetation. " Indeed, the term "solar" can be misleading, for what are really involved are a number of renewable resources.

Commoner provides a very sensible analysis of the potential of various of them - solar heating, photovoltaics, wind. He gives special emphasis - and a decidedly valuable Midwestern perspective - to the possibilities of heating, as well as manufacturing gas and liquid fuels, from biomass, primarily from wood and agricultural products. This subject, though potentially of great importance, is only beginning to come into national focus.

The Washington University scientist emphasizes, as have others, the importance of trying to match energy to its final need. That is, to fit the quality of energy to the service desired: "We have failed to integrate efficiently the production of energy with its use: that the links between the auto factory and the gasoline pump, between the power plant and the home, between the farm and the sun, are loose and enormously wasteful."

He also offers a mind-stretching idea of using natural gas and methane as the "bridging fuels over the transition.

Unfortunately, as Commoner gets away from solar energy, his arguments get murky. He allows himself to get caught up in the demonology that affects so much discussion on energy. He finds evidence of a great Carter administration conspiracy to perpetrate a major econometric energy model called PIES (Project Independence Energy System), developed by the Federal Energy Administration. His reconstruction of energy policymaking in the Carter administration is muddled. It is also quite mistaken in attributing a Ten Commandments-like authority to earlier versions of a mathematical experiment. He expects much too much of models. When he discusses the natural gas compromise, he again suggests demons were at work, totally ignoring the pernicious consequences of the old division between interstate and intrastate natural gas makers.

His view of the source of the energy crisis is so sweeping as to lose explanatory power. "The basic reason for the energy crisis is that the energy sources on which we rely - oil, natural gas, coal, and uranium - are nonrenewable." If that is the reason, we could have had the energy crisis in 1963 or 1953 - or 9123. What has changed? The first reasons - among many - for our present predicament are the heavy reliance on oil and the increasing asymmetry between who consumes and who produces. In other words, we are in trouble because the United States and the other industrial countries have become increasingly dependent on a handful of OPEC nations.

In arguing at the only two choices are between the breeder reactor and solar energy. Commoner does his own important case a disservice. For he is comparing something that is medium term - widespread diffusion of solar energies - with the breeder, something that technologically, at the very best, is decades away.

One of the most curious elements in this book is Commoner's dismissing of conservation energy as "peripheral." This is a serious mistake, for conservation itself is the real "bridging" fuel. It is America's best short-term energy source, outdistancing all conventional fuels combined. Indeed, Commoner is quite inconsistent, for on at least two occasions - discussing cogeneration and liquid fuels - he assigns conservation a significant role. But he is still against it. After all, conservation is one of the main reasons he does not like the Carter National Energy Plan, even though there was a lot more conservation in the Carter rhetoric than in the policies. He feels that conservation would deflect attention from solar energy. In fact, solar makes much better economic sense if it is first preceded by conservation. The two are complementary.

Commoner also dismisses prices as a "peripheral" matter. This is very puzzling, for actually in an economic system, just about any kind of economic system, prices are a rather handy tool for allocating resources and transmitting information. Even, one might say, necessary. Surely, Commoner does not want prices that "tell" us to use more and more of conventional energy sources and thereby reduce the incentive to move to solar. He plans to get around prices with what he calls "social governance."

But there is quite a bit of emotionalism in this part of the book, which really does get out of hand when Commoner compares the energy crisis to slavery. Not exactly an apt comparison, or one that does much to reduce the scapegoat-seeking that gets in the way of properly focusing the energy debate. Indeed, many generally sympathetic readers may find that comparison not only misconstrued but offensive.

Much as gasoline can be combined with gasohol, Commoner clearly means to spike his argument with polemic. Only when he gets beyond his cogent discussion of solar energy, the polemic becomes the base fuel. While that impairs the credibility performance, it considerably raises the volatility rating and thus is bound to make the book far more influential and popular than a more dispassionate examination. CAPTION: Illustration, no caption, by Jean-Francois Allaux