1 Again, it is a ratio.
2 The POCO gets paid for the extra energy generated, if there isn't any extra at least there's one less house drawing from the grid during the day.
More correctly: during some days.
3 The POCO around here in fact wants people to install DG, to in fact reduce demand and avoid new substation(s), so why would anyone disconnect their PV?
Then put the extra PV on a separate meter connected for grid sales. Put a separate PV unit just for your house load and let your house be free and clear of the grid. Go ahead. I dare you. No, I double-dog dare you!
4 The value of car battery is in its ability to deliver 1.78Wh in *four seconds*. A battery that delivers 6Wh over one day is completely useless.
His point was an illustration about how demand works and how it gets overlooked in PV financial calcs.
5 internal combustion is noisy and pretty expensive no matter where you are.
Then run something quieter. Simple isn't it?
6 Well, aren't new grids and old grids completely different things then?
In one sense, but they both have to be managed and are part of the continual planning process.
7 That's one of the main advantages of BESS with PV- it balances out the availability for grid AND consumer.
No doubt storage is one of the big hurdles for PV systems.
8 That stuff about clouds and voltage drops, etc is pretty interesting
Did I mention voltage drops?
9 so grid people must prefer these newer, fancier inverters that can actually help balance drops and such?
Certainly those that will integrate with the grid better. Not sure if that problem is solved yet though, at least to any appreciable degree.
In what world do you think 1 is the best? Actually it is not so good from a DG standpoint.
1 What I'm hearing about this ratio thing is really "less $ for the POCO coming out of the pipe". When someone produces more energy than they use, there is a little more energy in the pipe, and one less person paying a bill.
Around here there's a limit- total kw of DG on a feeder must be < 6.7% of the "peak draw" on that feeder. In my neighborhood that would be over 500kW, and there's currently <100kW.
So we could just say the ratio is around 6.7% then.
2 Yes, some days, but isn't "some months" more accurate? There are a lot of variables there. For instance, a system which doesn't quite cover usage in the winter will cover 2x usage in summer due to longer days.
3 That is actually an option, as far as I can tell. As long as the two systems <= 10kW or 25kW, depending on service. They do set you up with a meter for PV ouput and a meter for usage even for one system.
Pretty sure two "separately derived" systems are ok.
4 Ok, but he didn't really expound on how calcs should be done...so what's the "right" way then?
5 Ok, so diesel gens aren't always the best way! Glad we agree.
6 Right, the 6.7% thing could end up being even higher on a new feeder, conceivably.
7 Going from 14 cents to 2 cents is a pretty big hurdle to clear!
“Using conservative assumptions and no incentives, our model indicates that the incremental cost of storage will decrease from ~14c/kWh today to ~2c/kWh within the next five years,” the report says.
http://cleantechnica.com/2015/03/04/energy-storage-could-reach-cost-holy-grail-within-5-years/
8 You mentioned clouds moving across PV arrays affecting the grid- they do that by causing voltage drops...or is it drops and then spikes? Or...?
9 Why is a power factor of 1 not the best? From what I've read about reactive power, the closer to 1 the better.
You have total control over an engine by adjusting the fuel feed until you run out of fuel. Solar panels are like sail boats. If cloud goes over, you'll drop the load. Something HECO (Hawaii Electric Co) has been experiencing problems with. You'll need an expensive UPS system to provide ride through capacity and if the capacity doesn't return within a few minutes, you're screwed.
When solar is a small percentage, a variation is not a big deal. If a bus gets over crowded, people might experience a bit of an uncomfortable ride. But what if a bunch of people are waiting at the stop and the bus doesn't show up?
No, because solar industry arithmetic assumes 20 miles of one seat on Sunday night is worth the same as one mile of 20 seats in middle of downtown at 8AM on Monday morning.
Right off the bat, Enphase was able to prove its microinverters were accurate as sensors, by showing that they had recorded past voltage spikes that correlated to HECO’s system-wide voltage readings. “That gave them confidence that the data is accurate,” he said. Interestingly enough, Enphase's data indicated that voltage fluctuations on the circuits showed little correlation to how much solar PV was installed on each circuit.
The primary issue for solar-heavy circuits, instead, had to do with the age and quality of the power-conducting cables and transformers on each circuit, he noted. “A 50-year-old network can act very different than a brand-new network,” he said, with older equipment showing more propensity for problems caused by out-of-range voltages.
http://www.greentechmedia.com/artic...g-enphase-data-to-open-its-grid-to-more-solar
(the bus ride analogy)
To be fair, a vast number of residential rate structures assume the same thing for ratepayers without DG.
Exactly. Unfair would be the POCO paying residential customers the same amount for their personal PV generation as they pay the coal or gas plants.
Anyone who dumps a bunch of $$ into PV should be able to make it back in a timely fashion.
Utilities are a public service- so is a house with PV, just a lot smaller.
