Getting off the grid even partially is an obstacle course, but surprisingly, the biggest obstacle is not technology, it is financial decision-making at all levels. From the top down, with various federal programs, down to the level of the individual homeowner, there are some severe misunderstandings and pervasive analytical blunders that generally lead to inferior projects getting priority and the best projects often never being discovered. The combined result is often an unintended subsidy to the fossil fuel industry, and unintended decreases in long-term real estate values because owners fail to uncover the financially optimal decisions for their properties. Renewable energy is generally better financially because it comes with lower operating and maintenance costs, mostly negligibly low fuel costs, for backup mostly, and usually nearly little or no maintenance.
By comparison, investments in energy efficiency, as long as you're on the grid primarily, are really not investments at all, they are about operational savings. There are many other traps, and often times they are made worse by various government programs however well intended. Not only do many programs that purport to support renewable energy barely do so, their results are often antithetical to what they claim, and the postponement of the low-carbon future is the effect. To get largely off the grid these choices need to be made very carefully.
Solar PV: green energy for the postcards to send to mom
Look ma, we've gone solar!
- The Solar PV Model
It makes a nice postcard, but does it make financial sense? Getting Off the Grid is slowed down by solar PV compared to the alternatives, but solar PV is generally easier (read: cheaper) to install. However, Solar PV efficiency, remarkable as it is, is in the range of 15-16%, while solar thermal is up to 98% efficient, in other words, you are gaining more energy per square foot by a factor of 5 from solar thermal, and the overwhelming energy demand in residential living is thermal: Domestic Hot Water (DHW), Heating/Cooling.
The main reason solar PV gets so much press is because it is easy to deploy and because there have been a lot of tax-incentives. It may not necessarily be the most sensible investment. But everything differs from property to property based on implementation details. The principal driver for PV is that because it produces electricity, transportation is easier, but that argument may not hold water if it is installed locally for local production. Also PV has been the beneficiary of a lot of tax incentives, but for residential use, it is at best a second choice, rarely the first. In short, if you own a piece of desert in Arizona, and you need to transport the energy long distance, solar PV is a great choice. For your house, maybe not so much.
Off the grid: the secrets of Solar Thermal versus Solar PV
With solar thermal, you will find conversion efficiency as high as 98%, or easily 5 times higher than with PV, but integration costs may be higher, however in most cases thermal should win out if it is properly evaluated.
The most important thing is that with solar thermal the sun's energy is captured as heat, which is directly usable for DHW (Domestic Hot Water), as well as for heating and cooling. Perhaps even more importantly, that thermal heat can be captured and stored in the cheapest battery of them all, a hot water tank. Storing energy is the single biggest (read: most expensive) problem, and with solar thermal that problem is solved. We're talking seriously green energy here, and a major step towards getting off the grid. You are now building an energy system. If you think about the cost of real estate, and the frequent limits on available space, that higher energy efficiency per square foot should not be underestimated.
Tankless water heaters: throwing out the batteries with the bath water
As a home owner, your mission is not to burn gas most efficiently, it is to increase your living comfort, as well as the value of your home. As I've pointed out in the previous post in this series, tankless water heaters, with or without Energy Star labels, seldom make any sense if you evaluate the energy infrastructure of your home properly. The example of solar thermal here makes it clear how important Domestic Hot Water can be as an energy store. Too often there are incentives, such as low-cost financing, and or tax benefits, which seduce home owners to make the wrong decisions. Domestic Hot Water as a free energy store is very valuable in the energy household of your property. Other forms of batteries tend to be expensive.
Conclusion
As noted elsewhere, when visiting salesmen come to your door, and try to sell you equipment based on tax incentives, and other programs, and showing you a fantastic payback period based on reducing your energy bills, it's katy, bar the door, and go do your financial homework first. They are interested in their commission, not the value of your property, unfortunately many counter productive government and state programs seem to reward the wrong decisions, and unwittingly favor the incumbent energy providers, to the detriment of long-term real estate values.
Only by doing a proper long-term energy plan, and evaluating the alternatives, do you have a chance of making the best decision. A 30 year model is usually adequate, given the lie spans of a lot of energy equipment, not to mention the length of a typical mortgage. Start thinking of your property as (potentially) your own private energy plant. Don't be seduced by all the incentives in the world. Remember this: advantageous financing can never make a bad project good, but it can only make a good project better.
Hopefully we will also see modifications of various program, including financing packages, which often turn on specifying Energy Star rated equipment, and very often force property owners to over-invest in the wrong parts of the plan, or make the wrong choices altogether.
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