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Would it make sense to draw power at night from the grid, and store it in batteries for use during the day? Answered

I was flipping through Make:18 that was talking about energy use. I realized that some people include a large battery array in connection with their solar setup to provide power for their EVs, or potentially their house... So stepping away from that, could you take a large battery array, and have it store up power during the night, to use during the day? This would offset grid consumption during the daytime hours (when it's higher), and potentially lower energy costs (as drawing power at night is sometimes cheaper... although that would probably be negated by the battery array)


I love this question. I have been thinking about this for years. Ever wonder why wind farms don't run at night? No place to store the power in a cheap way. I have been toying with mechanical energy storage... Durring the night the wind farm powers an electric motor that lifts a rather large weight. Durring the day, or peak usage time, the system reverses... the weight slowly falls turning the same motor (now generator). Issue is, it would have to be huge to have any real benifit. Figure this problem out and you solve one of the worlds problems. Recently some architects are toying with the same idea for cooling buildings. At night when the power is cheap, freeze some water. During the day let it unfreeze to cool the building. I am excited to see how the system works.

No I don't think so; because it would cost so much to buy the batteries you would probably never gain back the money you spent.

Cost of batteries is indeed the largest challenge. Inefficiencies are another -- charging and discharging batteries will always result in losing some energy. But in fact some electric companies themselves do something very much like this -- they use extra power at night to pump water into holding reservoirs, and then use that water pressure during the day to run hydroelectric turbines. And there have been some designs proposed for very large, and rather fancy, battery/fuel-cell hybrids which would be able to store large amounts of power. At home... I think when you figure the cost of the batteries you wouldn't break even. But as manufacturers keep coming up with higher-powered batteries to drive electric cars and the like, that may change.

orksecurity, I think your Answer is the best here, but I can't mark it as such because yours is a reply to another. Just wanted to let you know. To anyone who answered, thanks for the info. I greatly appreciate it.

It also depends how your electricity is metered. Most residences pay a flat rate regardless of when they use the electricity. Time-based rates are more common for large businesses, facotries, etc. Around here (Northern California) some factories switch to night shift on hot summer days to take advantage of cheap electricity. Others will store it overnight. Check your electric bill to see if they actually offer a different rate for off-peak use.

I 100% agree with everyone below: It'll never pay off money-wise, but environmentally there might be some merit to using power off-peak, when power generation facilities are running at lower capacity - that's just a guess though.

Long running storage methods include pumped storage and storage heaters
If you could charge on a lower night-rate you might save some cash, but it'd take a while to cover your costs. Offset grid consumption is something best done on a gigawatt scale (first link)