The image is courtesy of ABCsolar.com, a commercial vendor, and it explains at a glance the appeal of solar electricity as it is practiced in many states with tax credits and rebate programs. Panels on the roof feed the grid, slowing the spin of that electrical cash register and sometimes even spinning it backward, selling power back to the grid at regionally mandated rates, sometimes identical to retail.
We’ve weighed in on the topic before, but the discussion, globally and blogospherically (is that a word?), is heating up (intentional pun, not funny but vitally important). Why are the systems set up this way? Here are five points, in descending order of priority, to explain the issues.
One. The grid needs help. Our electrical infrastructure is aging and stretched, and panels on America’s rooftops spell R-E-L-I-E-F for the power stations and the distribution network during peak usage hours, which happen to coincide with peak solar production hours.
Two. The math is simple this way. Since home-generated solar electricity can be used by the grid, the simplest calculation is to use the meter in two directions, in and out, and let lower power bills be the immediate reward for an investment in renewable energy for homeowners. Different utilities reward solar power sold to the grid at different rates, and some are capped as to yearly total power contributed from a single system. My local utility, Connecticut Light and Power, uses the Net Metering System, in which the meter simply registers resold power at retail rates. Even I can do that math.
Three. Grid tied systems are less costly. At quoted rates a nominal 5000 watt grid tie system costs the homeowner about $18,000 with all rebates calculated, and some quoted prices are higher. Similar systems involving storage batteries and charging and regulating equipment would cost considerably more, and payback formulas would be even longer than they are now (12-20 years, depending on who’s doing the math). The benefit of being able to use stored power at night and in bad weather is dearly bought on those terms. And remember, when the grid goes down, the panels are cut off, even in sunny weather, for safety reasons.
Four. The good news is the bad news. Most of us have very reliable local utilities who keep us well supplied with power, reducing our need for backup systems except in unusual circumstances (storms, blackouts, local line failure). Other countries have much less reliable utilities, and rolling blackouts are a part of life even in other developed countries. The incentive for grid independence, except among those in remote locations and cantankerous old hippies with long memories, is not compelling .
Five. Living with backup systems is a pain. Most Americans worship at the Church of Convenience, so to speak, and planning power usage to coincide with daylight hours while reserving battery power for small loads at night is too much thinking. Battery systems capable of running central air and electric ranges would be huge and expensive, and Americans who spend their days out of the house aren’t able to easily plan activities like clothes drying, cooking and water heating.
So—- for now, this is what’s possible. Solar power with storage backup is too expensive for modest budgets, too slow on payback to be an attractive short-term investment, and too short on equipment life cycle to be an attractive long-term investment. But the numbers do work: solar power pays, eventually, modestly, reliably, efficiently, philosophically, politically. For those able, in these straitened economic times, to take advantage of it, it affords a chance to be in on the ground floor of something that all of us will eventually join. For now, you might need that home equity as a safety net for your family. There are so many other energy measures that are very much within our reach. Let’s do those first things first.