Solar Panel Discussion

[Dsinned]

I don't know what "DWP" requires, but the simplest metering of a PV system is to merely use a NEMs meter from your utility co. This is nothing more than a "bidirectional" Killowatt-Hour meter with a built in transmitter that communicates with the utility co. for day to day data collection purposes. These meters usually look the same as a digital "smart" meter, and can be used for TOU electricity rates for the whole house including "credit" for the reverse power generated by a PV system. There is usually no extra charge for such a meter to be installed because the utility co. only has to "swap" meters, which only takes a few minutes. However, this will not occur until your "PTO" (Permission to Operate) is approved for your PV system. This may take up to typically 1 to 2 months.

 

[smkettner]

The beauty of TOU is selling power at 49 cents and purchasing at 9 cents. (Southern California Edison)
The 5 to 1 spread is a total rip until you turn it back on the power company.
I have used 447 kWh (net from SCE) this month and my bill is a $2 credit. There is no way to do this with normal tiered rate net metering.

 

[TonyWilliams]

The beauty of TOU is selling power at 49 cents and purchasing at 9 cents. (Southern California Edison)
The 5 to 1 spread is a total rip until you turn it back on the power company.
I have used 447 kWh (net from SCE) this month and my bill is a $2 credit. There is no way to do this with normal tiered rate net metering.

It's similar with my smart meter and solar at San Diego Gas & Electric. Since I'm at 100% home electric use provided by solar! the TOU stuff really doesn't affect me.

My EV's are on a separate meter for the cheapest utility rate between midnight and 5am.

 

[miimura]

My EV's are on a separate meter for the cheapest utility rate between midnight and 5am.

Do you have any solar on your EV meter?

I purposely did not get a second meter so my solar can offset my car. Only later did it occur to me to split the system so some solar feeds each meter. I've never heard of anyone actually doing that though.

 

[Tee2]

Sorry. DWP = Department of Water and Power. Full name is Los Angeles a Department of Water and Power. They're my utility. They have reduced rates for nighttime EV owners but they don't require the second meter anymore, at least to claim the home charge station $750 rebate though they do say you'll need it to capture the reduced electricity costs.

I guess when you consider selling them power at peak rates during the day reclaiming it back at cheap rates at night it makes sense to get the meter regardless.

 

[jspearman]

I have a 15.4kW Sunpower system. It's a lease, but I bought out the lease up front, and I can buy the whole system at year 7 for around $1,200. It ended up being way cheaper than purchasing the system outright, and it means we don't take care of the maintenance.

We have two Sunpower-branded inverters, but I think they are built by SMA. One of them had a problem after about a year, and then again about a month ago. The second occurrence they replaced the entire unit, but half my system was down for over a week, which was a bummer.

Our house was/is very inefficient, which is why we have such a big system. The vaulted ceiilings really kill us during the summer, but to fix the efficiency issues would've easily cost us $40K. The solar cost us a little less than $20K, and we overproduce about 4-5,000kWh each year, which means our bill each month is $0, even though we charge two cars (25-26Kmi per year). I don't mess with the TOU plans, which means I don't spend any mental energy on what is running when. I was like the Kim Jong Un of energy use when we were doing TOU before solar.

So I'm for leases, but only if you buy them out, otherwise the savings are pretty slim. The payback for my system, if you figure the savings in gas, is around 3 1/2 years.

 

[Tee2]

Who did your system? I just got a quote from Petersen Dean for a 7.5 kWh system for $35k, though what they spaced out for me uses micro inverters rather than single string inverters (I'll have some shade issues on a few of the panels) and they tell me that my roof type adds about $4500 to the cost as well since it's a nearly flat hot mop configuration.

After incentives and rebates it's comes down closer to $22k.

 

[TonyWilliams]

My EV's are on a separate meter for the cheapest utility rate between midnight and 5am.

Do you have any solar on your EV meter?

I purposely did not get a second meter so my solar can offset my car. Only later did it occur to me to split the system so some solar feeds each meter. I've never heard of anyone actually doing that though.

It's a net sub-meter, not a totally separate meter. So, my total production goes through the net meter, and EV use is subtracted and priced at the special rate.

 

[miimura]

My EV's are on a separate meter for the cheapest utility rate between midnight and 5am.

Do you have any solar on your EV meter?

I purposely did not get a second meter so my solar can offset my car. Only later did it occur to me to split the system so some solar feeds each meter. I've never heard of anyone actually doing that though.

It's a net sub-meter, not a totally separate meter. So, my total production goes through the net meter, and EV use is subtracted and priced at the special rate.

How long have you had the sub-meter? Are you in the new pilot program? I didn't think it was widely available, but then again, I'm not that familiar with SDGE policies.

 

[TonyWilliams]

How long have you had the sub-meter? Are you in the new pilot program? I didn't think it was widely available, but then again, I'm not that familiar with SDGE policies.

I don't know about "new" pilot programs, but I'm in the original EV program from early 2011.

 

[Larry_in_Seattle]

One clarification on the Enphase inverters. They're "designed" in California, but made in China.

I have 12 Enphase 215's paired with SolarWorld modules. Eight are 250's from last year, 4 are 255's from this year. (I've been in the solar industry for 12 years and have PV, Solar Pool heating, and solar thermal for domestic hot water on my home.)

 

[eschatfische]

We had 3.5kW of panels installed in May, which are on track to generate 5-6mWh each year. We have single-meter EV-A from PG&E. We use around 3mWh of power each year for our house, and around 6mWh for the RAV, with 85% of energy utilization being off-peak - so we figure that 5-6mWh of generation during partial peak or peak will either fully pay or come close to paying for all of our power utilization, and will also effectively eliminate all need to use utility power during peak periods. So far, the true-up reports from PG&E have all had substantial excess credits.

After much consideration, we decided to go with an SMA 3000TL transformerless central inverter when we had our solar installed.

There were a few things that tipped us towards the SMA, other than an acceptable price/performance ratio. First, the obvious installation strategy for us was an unshaded group of 12 panels on a flat roof - the advantage that micro-inverters have with splitting up panels just wasn't applicable to our install. Second was the secure power supply feature of the SMA, which allows us to switch the inverter from being a 3.2kW grid-tied inverter to being a 1.5kW off-grid inverter - meaning that in the event of a catastrophic grid failure, we can still have a power source during daylight hours to run the fridge and charge our phones and power supplies, or possibly even use the 120V adapter for the RAV. Third, the SMA was assembled in Denver, and was a good pairing for our Memphis-manufactured Sharp panels (and Fremont-assembled drivetrain).

Like Enphase, SMA provides a free monitoring service (as long as you buy the overpriced Ethernet module for the inverter). The inverter is dead silent, and can also support a second string of panels if we need to expand in the future. While transformerless inverters are still fairly new, I have to imagine that their lifespans will be substantially longer than conventional single-string inverters given the design; the fact that SMA now sells 20 year extended warranties lends credence to that assumption. I like what Enphase is doing, but I still think the SMA TL-series was the best match for us.

 

[Tadol]

We have a SolarCity system in Berkeley and an Enphase system up at Dillon Beach - they have both worked very well, and we've had no problems so far with either. I've started looking into adding panels to a commercial building we have, and the flexibility of sizing and potentially resizing systems as tenants and tenant needs change have me looking at the Enphase, but the issues with commercial installation have the project stalled -

 

[dstjohn99]

As the meter and main panel are located on an exterior wall near the master bedroom a large string inverter would be less desirable due the noise.

I have an SMA 4.5 kW inverter on the outside my bedroom wall. I've never heard a buzz or noise from it, unless I am outside standing right next to it and the cooling fan is on, then I can hear a slight whisper.

 

[dstjohn99]

The beauty of TOU is selling power at 49 cents and purchasing at 9 cents. (Southern California Edison)
The 5 to 1 spread is a total rip until you turn it back on the power company.
I have used 447 kWh (net from SCE) this month and my bill is a $2 credit. There is no way to do this with normal tiered rate net metering.

It's similar with my smart meter and solar at San Diego Gas & Electric. Since I'm at 100% home electric use provided by solar! the TOU stuff really doesn't affect me.

My EV's are on a separate meter for the cheapest utility rate between midnight and 5am.

I'm on SDG&E DR-SES (Domestic Rate - Solar Electric System) time of use rate. I looked at the EV options, but decided not to make a change. The EV off peak rate is only from midnight to 5am, but my TOU off peak is 10pm - 6am in the summer, and 6pm - 6am winter. Also it looks like the rate is a little less than the EV rate.

Ever since I switched from the "tier" based rate system, I have enjoyed very high "credits" for my on-peak & semi-peak excess production. The credits offset any power use at lower rates. So, for each excess kW produced during the day, I can buy abot 5kW at night. Then at the end of the year I get a check at about $.04 per kW for remaining excess.

For those considering TOU rates, you'll need to evaluate your usage carefully before making the switch. If you do not produce excess power during summer peak or winter semi-peak times, your bill may go up.

 

[dstjohn99]

Trying to decipher SDG&E current rates - a futile endeavor. For those interested, here is a link to their residential rates: http://www.sdge.com/rates-regulations/current-and-effective-tariffs/electric-tariff-book-residential-rates

The DR-SES and EV-TOU and EV-TOU-2 are the most relevant to this discussion. There are numerous tables and additional charges, but it appears EECC Rate + DWR Credit provides the most insight, as the additional charges per kW are constants. The dates below are basic guides, but they are modified by extended daylight savings time winter peak periods (I won't include that detail here, but here is a link to the various calendars: http://www.sdge.com/residential/daylight-saving-time-update

DR-SES EV-TOU EV-TOU-2
Summer (May 1 - Oct. 31)
On-Peak (11am - 6pm) .37916 (12pm - 8pm) .37129 (12pm - 6pm) .37224
Semi-Peak (all other times) .10856 N/A N/A
Off-Peak (10pm - 6am) .08323 (all other times) .09705 (all other times) .10036
(incl weekends and holidays for DR-SES)
Super off-peak N/A (12am - 5am) .04787 (12am - 5am) .04784

Winter (Nov. 1 - April 30)
Semi-Peak (6am - 6pm) .09277 (12pm - 8pm) .09536 (12pm - 6pm) .09150
Off-Peak (6pm - 6am) .07741 (all other times) .08375 (all other times) .08702
Super off-peak N/A (12am - 5am) .06095 (12am - 5am) .06057

The standard domestic rate (DR) is an overly complex tier system with a baseline rate determined by your climate zone, winter / summer and other modifiers (medical equipment...). A typical baseline might be 11kWh per day with rate increases when you exceed your baseline allowance, then additional increases at 131% and 200%.

I hope this "COMPARISON ONLY" information is useful to some. I hesitate to contact SDG&E about how an EV will impact my rates because I might not like the answer. I'm going to stick with the DR-SES due to the higher credits during on-peak and semi-peak, even though there is no super off-peak.

Maybe when I have an extra 30 hours or so I can decipher my solar production times vs rate schedules and usage times. I think some calculus will be involved. It makes my head hurt just thinking about it. I just want to drive my awesome RAV4 EV on free electricity!

 

[miimura]

I'm going to stick with the DR-SES due to the higher credits during on-peak and semi-peak, even though there is no super off-peak.

I have done extensive rate analysis on PG&E rates. The normal solar TOU rate schedule is structured the same way as yours but it is always more expensive than the EV rates that have lower Super-Off-Peak rates when you do a significant amount of EV charging. So, you should seriously consider the EV rates and using timers to take advantage of the Super-Off-Peak rates.

I've never tried to adapt my spreadsheet to SDGE rates but it should be straight forward because I've arranged all the time binning of SmartMeter data in a parametric way. My XLSX spreadsheet is available on Google Drive. If you're going to give yourself a headache, this is a good start.

 

[JasonA]

One clarification on the Enphase inverters. They're "designed" in California, but made in China.

This has been talked about countless times and also on the Leaf forum..

Some have inverters from Canada..or Mexico, it depends on where your vendor or supplier got the units from. I think most volume places were getting them from China and not directly from Enphase them self.

I know the IT dir in Petaluma and while we were setting up our system,we were getting all lined up for Suniva panels, etc..

Well.. Suniva ain't doing too well anymore so we got a fresh shipment of SolarWorld Mono's instead.. Oregon baby!

P.S. I think the Mexico inverters have a higher failure rate... just saying :roll:

 

[dipper]

Anyone has great service/installing experience in the SF South Bay Area?

I am thinking of installing one (to own) since this summer's EV-A peak rates are killing me.

 

[Dsinned]

I won't say the work was perfect, but my South Bay (SJ) PV was professionally installed by PetersenDean. Overall, they did a good job and I am a satisfied customer.

http://petersendean1.tru-m.com/powersaver-solar-cost-estimator/