JBee
Well-known member
- First Name
- JB
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A couple of things that might be interesting:This.
All grid usage/generation is time-based. Most solar generation is in the afternoon, but peak usage is in the evening, for instance.
If the utilities switch to demand-based rates, then consumers will change their habits to get the better rates, and the market will adjust accordingly.
Solar can produce just as much in the morning as in the afternoon, but can only produce as much as the grid has load, meaning that most solar in the morning has restricted output leading to less exports. This is not because of the sun varies it's output between the two times of the day though. In a lot of cases it is also dependent on how well the local time zone meridian overlaps with local solar time. For example: In Nashville the sun rose today at 6:43 AM and in the same time zone (GMT -5) it rose in Fort Stockton TX at 7:46 AM. This obviously changes when the solar midday is, and how human activity is scheduled in comparison.
In regards to ToU pricing the main problem is actually ToU itself. If you follow the graph above you will see that depending on the time of year the peak load in a household varies considerably, but peak household use remains dominate in the late afternoon and evening. This is because a lot of households follow a similar regimen, being; wake up, have breakfast, leave house, return to house in the afternoon (with kids) where household activities start, incl. dinner etc using power until late evening and finally sleep.
So even if ToU pricing would incentivize more even consumption, how do you go about changing these typical use profiles without disrupting how people go about their lives? Even if you would half the price I doubt you would see a 10-15% change in the usage profile. It's just not practical enough.
Another interesting element of the profiles above is also just how much cooling overlaps with potential household solar production, and how much of this load until 4-6PM could come from solar instead f the grid. In fact nearly half of the consumption in summer is cooling load that also follows the household occupancy pattern. Another option here would be use cheap and cost effective thermal storage (Insulated water tanks using thermal mass) to offset the evening peak into the solar production times, and with solar together essentially halving household demand in the summer. This load does not have to be electrical, and does not need it's own battery storage, which reduces the cost for running battery storage for the rest of consumption in the house.
Obviously, it's also evident from the graph that household EV charging overnight will increase the peak period until the morning. But here it is important to realise that the load of a EV charger when operational, typically exceeds normal household consumption some 2-3x. And as previously posted, only can use non-solar utility provided power to charge at those times.
"If" you had enough space on your house roof with correct orientation, you could actually take a large bite out of the middle of the daytime household consumption, which would give networks some more capacity during the day. But sadly as soon as the sun goes to low angles in the afternoon, that nasty evening peak will remain, and possibly even get worse as more households are built. But... if the EV's had V2G, or at least V2H, then those peaks could also be "buffered" out with battery storage.
In an ideal fashion, as is also proposed by the report, the EV's would charge at work, from solar during the day, and bring renewable energy home for use in the peak evening period when the sun goes down and everyone is at home.
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