Cheap Solar: No Batteries

Published on April 27, 2009 by Tor a.k.a. "Solar Fred".
Categories: Affordable Solar, Buying Solar, Solar Components.

Dear Solar Fred,

What’s the cost difference between having a system with batteries and a system without batteries? Is being off the grid worth it?

Sincerely,

Sam in Los Angeles

Dear Sam,

Great question. Short answer is that battery tied systems are NOT worth the extra cost for many reasons. Let me count the ways.

1. Most if not all State cash rebates require your solar panels to be connected to the utility. So you if you’ve got power going to your house already and you want free money from your State, then I would stay on the grid. (Go to the DSIRE site for summaries of state incentives.)
2. Grid tied only systems are relatively easy to install, requiring less time and money for installation costs.
3. Similarly, without batteries, you have to buy fewer pieces of electrical and safety components.
4. Being tied to the grid, you can take advantage of net metering and time of use rates.
5. Grid tied systems are very low maintenance. Battery systems, even those that are just backup systems, are less efficient, require more space and maintenance, not to mention frequent battery replacement costs.
6. For the 25 to 30 years of your solar panel life, the grid will almost always back you up at night and on cloudy days. It is extremely rare in America when the electricity goes down. Power is generally restored within hours or within a few days at the very worst.
7. If you consider that you’re not eligible for state rebates, you could be losing $20,000 or more between the rebate cash that a State like California would have given you, plus the extra equipment and labor costs.

To be balanced, battery tied people have some non-financial advantages:

• You can have it both ways. That is, you can be on the grid and have a battery backup system in case of a black out. (Consider how often this happens, however. In most of grid-tied of America, a black out may happen once a year or less. Is that worth 20 grand? If you’re in a rural community with no utility wires for miles, then it could be worth it.)
• Grid tied systems with a battery backup are still eligible for most State cash rebates and the 30% Federal Tax Credit. (However, neither of these discounts will apply to any batteries or battery components.)
• Grid tied systems with a battery backup need fewer batteries, less maintenance, and less space than a system that has batteries only. (But you still have higher install labor costs, extra equipment, and you’ll eventually have to replace the batteries.)
• With a battery system that is not tied to the grid, you can proudly say that you are completely independent of coal burning utility companies, that you use 100% renewable energy from the sun, and that your lights and refrigerator will be on after an earthquake or problem with the grid. (However, as noted earlier, you are also responsible for a separate, well ventilated space to house the batteries, maintenance of the batteries, and the inevitable replacement costs every 5-10 years–depending on how well you maintain your batteries.)

So it’s up to you, but if you really want the most affordable system that is 95-99% reliable and less expensive, I would go with a solar system that is only tied to the grid without backup.

Michigan Solar Incentives Updated »« Cheap Solar: Buy Half a System