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Comment by hueving | Hacker News Reader

You state the following as a given, which is exactly what your parent says is wrong.

>Most net metering programs take solar from a home when the grid is facing its highest demand and energy is most expensive for the power company. They then provide a credit to your bill in watts. With a solar installation, you're drawing energy at night, when the grid basically wants to give away power to keep things balanced.

Do you have a source that states production from solar meets peak demand?

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In Hawaii, solar meets peak demand during the summer, as in the summer they have a higher midday peak than evening peak. In winter the evening peak is slightly higher, however if you look at area under the graph rather than just at the peaks, it is obvious that solar correlates pretty well with usage in general in Hawaii.

http://www.hawaiianelectric.com/portal/site/heco/menuitem.50...

We can take it as given that solar panels produce the most power during the day, particularly when the sun is directly overhead. The assumption is that air conditioning and refrigeration is a major electricity use that consumes the most power when the sun is shining. Presumably that is the case for residential, office, retail, and most service industry use. There are industries whose electricity use is not correlated with time of day, but they're not based in Hawai'i. If you want evidence that the damnedpowercompany would like to give away power at night, take a look at their awful "security light" programs.

I've seen a couple of things recently that said that peak consumption (in California, at least) is in late afternoon and early evening, as people return home from work and turn on their air conditioners and other appliances. It's not right in the middle of the day, as you might think.

Probably depends on where in California. If you look at google maps in SoCal, it seems like almost every house has a pool. Pool pumps take a lot of power, and you're supposed to run it during daytime. Those 4-6 hours its running is our highest power usage.

Pool heaters take a lot of power. Pumps not so much. You can defer heating until a couple hours before you want to use it.

I can literally look up my hourly power usage online. The 4-6 hours my pool pump is on is almost 2x higher power usage than any other time. I consider that a lot of power.

Edit: we had our house unoccupied for 2 months with everything unplugged and off, but our pool pump and sprinkler system. Based upon that, and looking at our historical usage, I would say our pool pump accounts for about 65% of our monthly kwh.

Wow, it surprises me that it's that high, but you clearly know your numbers. Presumably the rest of your house is quite energy efficient?

If it something that interests you, you could probably reduce the power usage considerably by switching to a smaller pump that runs for more hours. All else equal, the power required for pumps increases much more than linearly (proportional to the cube of the flow), so a pump with half the flow rate that is run for twice as long would use less than half the total energy per day for the same amount of water circulation.

Martin Holladay is a trustworthy source with a good writeup: http://www.greenbuildingadvisor.com/blogs/dept/musings/your-...

That's not the case for residential, office, an industry use. The hottest time of the day is when electricity tends to peak in hot climates, which is not when the sun is directly overhead. It's usually later in the afternoon.

Example data from Australia (peak at 6-8pm, clear power mismatch to solar): http://www.aph.gov.au/About_Parliament/Parliamentary_Departm...

That's not at all what that report says. The graph in the report is talking about the energy usage and production of one household, not global demand. Peak global demand of energy in Australia is very much in the middle of the day as offices and other workplaces run aircon / lighting / computers / industrial processes.

For the most part that's just not true, the peak is in the afternoon evening nearly everywhere. Here's lots of other examples: https://www.google.com/search?q=power+consumption+by+hour+of...

http://www.poplarnetwork.com/sites/default/files/peak-shavin... http://static.squarespace.com/static/545e40d0e4b054a6f8622bc... http://1.bp.blogspot.com/_nLHRC8dC8wI/S8tjxUq6cxI/AAAAAAAAAD... http://www.northcoastjournal.com/110305/chart.jpg

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