Solar Help

So I'm revisiting the solar thing now that I have my leaf and my refi (Shaved 2 years off the loan, with the better rate!) is done.

My annual usage (before leaf) is 3845 peak and 5467 off for a total of 9312.

My guess on leaf charging based on my driving is another 200 kwh (8 kwh * 20 days) off peak a month.

so that would be something like
3845 peak and 7897 off peak for a total of 11743. But I understand from a cost perspective, with solar, it's easier to replace that extra off peak usage with on peak production.

So how do I size the system? Or is it not too important and should I just get something in the 5kw range? I understand there is a point of diminishing returns if you oversize..

SolarCity has a pretty unbeatable deal right now. I think I'm going to go for thei one payment lease, as soon as I can understand how big the system should be.

Thanks!

It is all in the varying rates. Just supplying usage is not enough information to calculate. would really need to know the varying costs of those different usage rates; 38 cents during day offsets 8 cents at night in a different way than 22 cents in the day offsets 11 cents at night.

Also our utility has a different set of rates during the HOT months than during october to may.

You should take the issues to three installers and ask them to run it through their calcs.
they have software set up to do that and the software also does estimates based on your latitude, angle of panels, shading, hours of daylight. etc.

Mine was engineered to produce just about 100% in 2008, then my utility began to offer Time-of-Use (TOU) meters. I got one of the first and I am overproducing because it is not a one-for-one swap,

Trust them, and verify buy comparing their calcs.

Just dont go crazy over a few hundred dollars amortized over the more than 20-year lifetime of the system. there is some pretty heavy breathing here by some folks over $2-5 a month on a car that costs 25k.

By peak and off-peak do you mean TOU? How much does your electricity rate vary between peak and off-peak usage? How does your utility handle excess generation?

If you have tiered rates, it's usually most cost effective to put in enough PV to offset the most expensive electricity.

You can go to PVwatts to estimate output from various size and configured systems.

I just got my 5.52kW system commissioned today.

I had the system installed by Sun Valley Solar. They also did the system for LEAFfan.

I generated 30kW today, my first day of production. I would highly recommend them.

PM me, if you would like some comparative stats from my home.

LEAFfan is SRP. I am APS. I am on a discontinued TOU plan (9am - 9pm).

SilverLeaf said:

I just got my 5.52kW system commissioned today.

I had the system installed by Sun Valley Solar. They also did the system for LEAFfan.

I generated 30kW today, my first day of production. I would highly recommend them.

PM me, if you would like some comparative stats from my home.

LEAFfan is SRP. I am APS. I am on a discontinued TOU plan (9am - 9pm).

Click to expand...

You mean 30kwh.

Goto
http://mapserve3.nrel.gov/PVWatts_Viewer/index.html

Very good resource.

The best ROI would be just big enough to offset the highest tiered rate from your utility for your highest month usage (prob summer). If you don't have tiered rate, it would just be how much panels you can afford.

If you size your system to be 100% of your yearly usage, your ROI would not be as fast, but good month (prob summer) you would make more than you use to offset bad month (prob winter), for no net gain or usage.

If you size your system to be 100% of your highest month, your ROI would be the least, but you have the satisfaction of knowing you're not using any fossil fuel at all for your energy needs. In this case you would prob have excess. In California, the Gov-inator (ex governor, actually) signed into law where the utility MUST pay you back for excess. This wasn't the case a few years ago, such that it was more important to size your system just below your total yearly usage. I don't know how AZ utility works.

As far as TOU (Time-of-Use) rates, that's a bit more complicated. I personally didn't bother to go that far.

thanks for the links.

So they are saying a 5kw system will produce about 7700kwh a year. That will cover all my on peak and with the proceeds of overproducing during peak, that should cover a good portion of my off peak. I think at this point some solar is better than no solar..

I am on a discontinued TOU plan (9am - 9pm).

Click to expand...

This is the plan I'm currently on as well. I had no idea it was discontinued. Will they let me keep it if I get solar? Still waiting to know the rates for the new rate the corporate commission promised for EV owners..

turbo2ltr said:

thanks for the links.

So they are saying a 5kw system will produce about 7700kwh a year. That will cover all my on peak and with the proceeds of overproducing during peak, that should cover a good portion of my off peak. I think at this point some solar is better than no solar..

I am on a discontinued TOU plan (9am - 9pm).

Click to expand...

This is the plan I'm currently on as well. I had no idea it was discontinued. Will they let me keep it if I get solar? Still waiting to know the rates for the new rate the corporate commission promised for EV owners..

Click to expand...

Yes, they will let you remain on your existing plan.

We installed a 5.0 kw system last year. we have 24 panels on 3 strings. The only mod I would have done would have been to have a larger inverter installed (SunnyBoy 5kw now) so that in the future we could add panels without a lot of hassle.

Last year before the Leaf we overproduced a lot, but we sized our system for two 24kwh electric cars charging every other night plus all our regular electricity. (We don't have AC)

We oversized because it seems to us that electricity is cheap compared to other utilities and in 5 or 7 years that may not be the case.

-u

occ said:

. . . . . . . . . snip The best ROI would be just big enough to offset the highest tiered rate from your utility for your highest month usage (prob summer). If you don't have tiered rate, it would just be how much panels you can afford.

If you size your system to be 100% of your yearly usage, your ROI would not be as fast, but good month (prob summer) you would make more than you use to offset bad month (prob winter), for no net gain or usage. If you size your system to be 100% of your highest month, your ROI would be the least, . . . . . . . . . . . snip

As far as TOU (Time-of-Use) rates, that's a bit more complicated. I personally didn't bother to go that far.

Click to expand...

As with most things in life, nothing is absolute. We've run both TOU, as well as standard tier'ing for our 1st 2 PV production years. Being paid for surplus (on a 100% sized system or even slightly larger) means that if you become more & more efficient, the utility will write you a larger and larger check for your surplus. Just as you the customer will pay more for higher tier electricity ... PV over-production works the same way. So if your over production goes into the top tiers, your pay back (ROI) comes quicker.

Similarly with TOU. Your more costly electricity (here, it's from 10AM to 6PM Monday through Friday) yields a bigger/quicker payback ... and when you're using cheaper power at night (when typically more folks are home), you end up eating away at less of your day time surplus. A smaller system would thus not benefit from daytime surplus pay backs.

turbo2ltr said:

So how do I size the system? Or is it not too important and should I just get something in the 5kw range? I understand there is a point of diminishing returns if you oversize..

Click to expand...

I believe the "diminishing returns" argument applies mostly to three cases:

1. If you have a tiered rate schedule, like everyone in California. You don't have that in Arizona, do you? (Tiered means the more you use the more it costs per kWh.)
2. If your utility charges one rate for electricity you use, but pays you a lower rate for electricity you feed back into their system in a given TOU period. Some, but not all, utilities do that.
3. If the utility has a "true-up" period, typically once a year, and you lose any excess money you had earned at that time.(i.e. If you owe them, you pay. If they owe you, forget it.)

Ray

But, consider these points to size larger:
1. all electricity is likely to get more expensive
2. inflation
3. increased usage for perhaps hotter summers
4. spending more time at home as you retire
5. wanting more A/C to be more comfortable
6. EV driving increases, needs more charging
7. more bad weather could reduce total generation
8. if you do not do it now, will you ever have more money later?
9. Some rebates are slowly being phased out.
10. very good PU tariffs could diasppear
11. would it be more difficult to add-on later

Hopefully these are worth some consideration.
Cheers

As of 23 March, this article was just posted on the following website; it speaks to this topic, at least somewhat:

http://solarchargeddriving.com/news/people/647-theyre-plugging-a-volt-and-a-leaf-into-solar.html

In my computations, I concluded that I needed an extra 1.4 kW production for the cars, but that was with TOU credit considered and drawing charge power on discounted special midnight to 7am TOU rate...

George Parrott

GeorgeParrott said:

As of 23 March, this article was just posted on the following website; it speaks to this topic, at least somewhat:

http://solarchargeddriving.com/news/people/647-theyre-plugging-a-volt-and-a-leaf-into-solar.html

In my computations, I concluded that I needed an extra 1.4 kW production for the cars, but that was with TOU credit considered and drawing charge power on discounted special midnight to 7am TOU rate...

George Parrott

Click to expand...

WOW !!
Check out the DC to AC conversion numbers. You plug in your DC number, and it spits out an AC result WAY lower than what many solar companies are promising you get. I'd read on a few PV solar sites that often, over promised AC conversion results happens, but never found it in a calculater. Interesting. It gave a sense of relief that our solar company (though I wouldn't recommend them anyway) built our system based on an AC rating.

Here is another article from Consumer Reports reviewing our home use:

http://news.consumerreports.org/cars/2011/04/a-tale-of-two-evs-california-man-shows-how-chevrolet-volt-nissan-leaf-can-pay-off-1.html

This just came up on this week in April.

George

turbo2ltr said:

thanks for the links.

So they are saying a 5kw system will produce about 7700kwh a year. That will cover all my on peak and with the proceeds of overproducing during peak, that should cover a good portion of my off peak. I think at this point some solar is better than no solar..

I am on a discontinued TOU plan (9am - 9pm).

Click to expand...

This is the plan I'm currently on as well. I had no idea it was discontinued. Will they let me keep it if I get solar? Still waiting to know the rates for the new rate the corporate commission promised for EV owners..

Click to expand...

Turbo,
APS will let you keep the 9-9 plan but you may want to look at a noon-7pm peak, plan.
On the noon-7pm plan they eliminate the "Demand Charge" fee you now see on your itemized billing.
Call APS customer service and ask for the "Green Team". When you go solar the green team will be your CS contact going forward. They can explain and run some numbers for you to show if this rate plan would benefit your usage.
It worked for me to switch plans.

I have my 5.52 kW system installed and operational.
I have retained my 9 - 9 (discontinued) plan.
My 9 - 9 is WITHOUT a demand charge.
The original 9-9 had options for both with and without demand.

The Net Metering is also PEAK/Off-PEAK, so the peak offsets peak, and the off-peak offsets off-peak.

BTW - My LEAF is at RAIRDON's awaiting paperwork exchange, and then ON TO AZ!

:mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen:

SilverLeaf said:

I have my 5.52 kW system installed and operational.
I have retained my 9 - 9 (discontinued) plan.
My 9 - 9 is WITHOUT a demand charge.
The original 9-9 had options for both with and without demand.

The Net Metering is also PEAK/Off-PEAK, so the peak offsets peak, and the off-peak offsets off-peak.

Click to expand...

I guess my point was that if someone has solar and is an APS service customer, they may want to check their billing summary to establish if they have in fact either a Combined Advantage plan or the Time Advantage plan covering the hours of 9am to 9pm.

One plan does have a demand charge fee and one does not. I don't believe they are explicitly titled to indicate the extra fee but the itemized summary of usage will have the demand fee listed if you are paying that fee.
If I had the 9-9 rate WITHOUT the demand fee I most likely would not have changed plans.
Just a courtesy FYI for APS service area solar folks.

Reviving this thread..

So after SolarCity did a site audit a few months ago, they finally sent me the engineering details for my approval. The problem is "due to structural reasons" they could not do the reverse tilt for one of the planes. They adjusted the guaranteed production down 800kWh/year. Overall it was 11.3% less than the original estimate.

The thing is they didn't adjust the price at all nor did they do anything to make up for the lost production. The size of the system was picked specifically based on my usage plus (at the time) an estimate of how much power I'd use to charge the leaf with the assumption that they could do the reverse tilt. And what's even odder (at least right now since I didn't really look into why) is that the claimed estimated average price per kWh over the lease term went from 6.4 cents to 5 cents. How do they come up with that if you didn't change the price of the system and you produce 11% less? I dunno.

So I said something and they are "working on options".