I keep hearing how the (US) grid needs updated to handle the influx of renewable plants, but wouldn’t rooftop grid-tied solar help with this in the short run?
I had a small 1.5 KW proof-of-concept grid tie PV system at my old house, and the way it was described (and appeared to operate) was that it offsets any local usage, reducing the amount drawn from the utility/grid, and if there’s any excess, it’s fed back out.
Assuming small setups, wouldn’t that help keep demand lower and put less stress on the grid? I mean, if you’re exporting tens of KW from a large PV setup, it still has to go through the transformer (which is what the article is focusing on), but small/medium setups that don’t quite meet/exceed your usage would presumably reduce that grid stress.
Or am I missing something?
What you’re missing is that rooftop solar in the US is insanely expensive — about 4x what it costs per watt on average in the rest of the world.
This makes it more cost-effective to do other things instead.
True. I lived out in the boonies at that time, had plenty of space, so my setup was ground-mounted. Made the costs much more bearable.
I think you are correct. I think it is mostly FUD by large generators. Not that the grid doesn’t need updating but it’s not due to distributed generation yet.
If I were going to do solar today I would do grid isolated with automatic transfer switches. The panels are much cheaper, you get power when the grid is down, and you have more granular control over how you use power.
Yeah, I’ve always assumed those arguments were at least partially FUD, but our grid is aging and struggling already, so I know there is some truth to it.
Grid-isolated + ATS would be the way to go, assuming batteries aren’t a (cost) barrier. It also avoids the pitfalls and artificial BS you have to deal with from (some) power companies if you want to setup net-metering with a grid-tie system.
The setup I had was small enough to fly under the radar, but when I talked to them about setting up net metering for a larger setup, it was such a sham:
- They install a second meter that your PV system ties into. Only your PV can hook into this. It’s configured to meter the power flowing out at wholesale rates. There is a monthly “meter fee” for this (same as your meter fee for your regular hookup - approx $12/mo)
- All your local usage has to go through your regular meter at retail rates.
- The PV goes out the wholesale meter and back into your retail meter; excess goes to grid
- You’re billed normally on your regular meter
- Power company credits you at whoesale rate for the amount fed through the PV meter.
So, in effect, you generate power, ship it out at wholesale rate, and then buy it back from yourself at retail with the power company pocketing the difference.
Talk about a racket.
Edit: I didn’t realize exactly how much of a racket it was, but here’s some napkin math:
Assumptions:
- Monthly power consumption is 1,000 KW/h
- 5 KW PV system that, unrealistically, produces full power 8 hours a day, 30 days a month
- Retail rate of $0.25 per KW/h (my current rate)
- Wholesale rate of $0.16/KWh (guessing on this, but it’s proportionate to the wholesale rate I was quoted when my retail rate was $0.14/KWh)
5 KW * 8 hours/day * 30 days/mo = 1200 KW/h PV at $0.16/KWh = $192 - $12 meter fee = $180 bill credit
1000 KWh usage * $0.25/KWh = $250 + $12 meter fee = $262 bill
$262 - $180 = $82 bill even though you produced 200 more KW/h than you used.
I would be very selective on where I used battery power, if at all. At the moment I think I would use grid power instead. For air conditioning I would get the house as cold as I could while the sun was shining then coast throughout the night. Same for the refrigerator. I would run the table saw on dc directly from the solar panels.
Much of the existing grid’s issues could be fixed with reconductorting. Changing the design of renewable interconnect for half-cycle ride-through and power-factor compensation would have been interesting but now there is so much capacity this is practically inconsequential.
As DC interconnects becomes more common the grid becomes more resilient and flexible. Most of these are paid for with private investor money.
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