Wednesday, April 8, 2009

On-Grid or Off-grid: Which way to go

Now that it's springtime more people are thinking of adding solar power for their homes and businesses. The federal solar investment tax credit along with more local and state incentives help with these decisions. Having sold residential and commercial systems since 2002, a portion of my customers have asked about going totally off-grid. During the contrived "energy crisis" here in California in 2000-01, many wanted to go off-grid to get back at the utilities who, as it turned out, were complicit in creating the shortage.

But now let us reason together.

Only in those remote areas where the regional electrical grid has not yet reached would I recommend solar (or wind) power. Solar panels are a reliable source for power but a battery bank is required for storing electricity. Batteries degrade a lot faster than panels and most people would not want to maintain a battery bank if they didn't need to but the technology is there, if necessary. Another issue disfavoring off-grid solar is that many incentives only cover grid-tied systems. (See "Solar Incentives by State" in Related Links)

Net metering is a cool thing for ratepayers using solar power. If for instance a family uses 700 kilowatt hours in a month and the rooftop PV system produced 500 kWh, the family is only charged for the net consumption from the utility, 200kWh. It's as simple as that. In places like California, the investor-owned utilities use tiered billing systems which increase the cost per kWh as the consumer uses more. In this case, solar covers the top 500 kWh leaving the remaining 200 in the cheapest (baseline) rate. So while the 500 kWh covers 71% of demand, it could defray 80% or more of the actual charges. Better yet, grid-tied systems qualify for all rebates, feed-in tariffs and tax credits without requiring a battery bank.

Back-Up Systems: If you live in an area where weather plays havoc with the power lines consider a back-up system for your solar installation. Some inverter makers like SMA America make inverters that work with the grid but also trickle charge battery(s) for temporary back-up power. These cost a little more but can be worth it. The question one should ask is "How often does the power go out for more than four hours in a year?". If it doesn't happen but maybe once a year, don't bother with back-up. It might get you bragging rights with your neighbors that you have some power when they don't but it likely will not justify the extra cost. Just keep your refrigerator and freezer closed until the utility is back up.


No comments:

Post a Comment


web site visitor stats
DVD Rentals