EV+PV - Who Has It?

[TeCKis300]

Speaking of peak efficiency...

I just learned how much dirty panels can impact power production. Ever since installing, I've only ever seen my 4.8kW system output a peak of 4kW. Just yesterday for the first time, I was curiously seeing peaks of almost 4.5kW.

Turns out, the immediate weekend I had the panels physically put on the roof, I was doing a large landscaping job in my yard, and moving about 20 cu. yrds. of dirt with a bobcat. That put a nice layer of dirt on the panels which I did see prior, but didn't think much about. The night before seeing the large jump in production, saw some light rain fall which likely washed the panels.

I have a relatively new style AU Optronics 'AC' panel, which is microinverter based, but has the inverter integrated to the panel at the factory.

 

[TonyWilliams]

I made 1.25 MWh for March 2013.

 

[VQ EV]

I wanted to go with micro inverters, but it would have rased my cost from $2/watt to $3/watt. Now I'm glad I went with the 2 inverters in the garage. I heat the 12 aquariums in my garage with about 4 kW of electric tank heaters. Now the wast heat off the inverters almost eliminates their consumption. I hope my big exhaust fans I use for humidity control can handle the extra heat in the summer.

 

[TeCKis300]

Without shading or layout issues, string inverters still have a pricing advantage. Though if you factor in the replacement cost of the string inverter at ~10-15 years down the road, it may bring the price points closer. Sounds like your situation is ideally suited for the string inverters as you're even taking advantage of the waste heat! That aquatic setup you got there sounds pretty awesome.

I was able to get my system installed for ~$2.50 after federal rebate.

From a labor cost perspective, the AC style inverters install similar to string style inverters, and might actually be simpler yet. There is no roof assembly of separate inverters, and the associated extra connections between the panels/inverters, extra mounting of individual microinverters to the rail, and extra grounding of the inverter and panel independently. Then it's simple standard 10/12 gauge romex to the breaker panel.

Any way you do it, gotta love EV+PV.

 

[Dsinned]

I have a relatively new style AU Optronics 'AC' panel, which is microinverter based, but has the inverter integrated to the panel at the factory.

Yep, the accumulation of dust, dirt, bird dropping are definitely a detrimental factor. This time of year - early Spring - lots of pollen getting airborne. I'm seeing a light coat of "yellow-green" dust getting all over my cars every day. The rain helps to clean it off, but just encourages more plant life to pollenate all the more. I suspect there is a fair amount of that dust-like stuff covering my solar roof now as well.

Are your Optronics integrated AC models more costly than the getting separated components? Are they based on Enphase microinverters? What size (# of cells) are these 'AC' panels, and what is their power rating? I suspect these will become more popular when their cost comes down; for sure they should lower the installation cost of a solar roof system.

 

[TeCKis300]

I strongly considered an Enphase system, and was given a competitive bid using that hardware. Though my choice came down to other reasons, and I would have been equally happy with an Enphase system.

While I haven’t strictly priced them out separately, the AC panel prices are likely slightly less expensive than buying separate PV panels and microinverters. The AU Optronics panels uses a Solarbridge brand microinverter rated at 225W max output. The panels are 60 cell 240W max output, which pairs well with the inverter

 

[Dsinned]

My Enphase microinverters are the latest generation "M215" type, with an absolute max output power capability of 225W. I'm using Canadian Solar 250W (60 cell) panels and have yet to see any evidence of "clipping", although a couple days ago, my 3.5kW system reached a peak output (3150W) just below that point. Are your Solarbridge microinverters as good as Enphase microinverters in term of Efficiency (96%)? And does your system have a monitoring capability equivalent to "Enlighten"?

 

[the2bobs]

Dsinned - I'm very relieved to hear about your great experience with PetersenDean. I'm putting on a 3.68 kW array hopefully in May through Paramount Solar with PetersenDean as the subcontractor. The pricing ended up being $400 over the PowerSaver series and then I upgraded to the M215 units as well for the same reasons as you. I've been planning on moving from my Prius to an EV at some point but had only really looked at the Leaf until I heard about the great deals on the Rav4 EV. Hearing everyone's success stories definitely reassures me that I'm making the right choice. PetersenDean's pricing is ridiculously cheap compared to the other vendors I got quotes from which made me nervous about their quality but you've given me the warm fuzzies I was looking for. I only wish I had found this forum earlier so I could have given you the referral

 

[TeCKis300]

My Enphase microinverters are the latest generation "M215" type, with an absolute max output power capability of 225W. I'm using Canadian Solar 250W (60 cell) panels and have yet to see any evidence of "clipping", although a couple days ago, my 3.5kW system reached a peak output (3150W) just below that point. Are your Solarbridge microinverters as good as Enphase microinverters in term of Efficiency (96%)? And does your system have a monitoring capability equivalent to "Enlighten"?

The SolarBridge microinverters are very similar to the Enphase units and likewise comes from a company within Silicone valley. With similar efficiency and similar per panel monitoring. I did look into the web link for your system, and I would give the edge to the Enphase units for their web monitoring portal. It’s very cool to pull up their geo-map of installed systems and be able to check out the other installed systems. While I opted to ‘share’ mine, I can’t seem to find a public link to share with you at the moment.

In terms of clipping, my research found that even if it did clip at peak production, the opportunity lost is almost insignificant, since the system spends very little time at peak output. It’s not until you pair a 290W+ panel with a 215W inverter, that you’ll begin losing any significant production. The bigger factors by far are at the physical level of having the panel at optimal facing and alignment.

 

[Dsinned]

the2bobs, thanks for reading my posts about all things "green". In some ways, PD does seem like they may not be a top notch company, but I have no complaints, except their responsiveness leaves something to be desired, and some of the paperwork/recordkeeping they do is kind of error prone. I do agree about their pricing. Seems quite good! The only other thing I'm not wild about with them is their PowerSaver Series purchase contract gives them the rebate from CA CSI. In my case, that turned out to be $592, so they can "afford" to be generous in other areas.

I am currently working with them again right now to add 3 more 250W PV panels and M215 microinverters, to upgrade to a 4.25kW system, but they are saying I have to buy them in sets of six as normally would be sold in their PowerSaver series. I also heard recently, they are not doing any more Enphase based systems. I have also discovered they are not too keen on doing anything "extra" like installing an Enphase RGM, so monitoring my system will be much more precise (+/-0.2% accuracy, while recording and reporting system output power measurements).
.
.
.

TeCKis300, if you go to your "setting" page and scroll down, there is a URL string provided that you can cut and paste to allow visitors to see your system. Also, there is a free PC app called, "Generaytor", that allows "sharing" (and comparing) fellow subscribers' solar systems via their website. It is quite nice but lacking enough subscribers to make as good as it can be. In the N. CA area there is only a handful of users there, so it is tough to find and compare systems equivalent to my own, although they have a simple "normalization" scheme for doing comparisons to make it more of an apples to apples kind of thing.

As far as "clipping", I think we are saying the same things. From what I've read, its really the "area under the curve" that can matter most, not the clipped (lost) amount of production above the peak(s). Obviously, there is a point of diminishing returns. However, within reasonable limits, the larger the PV panel's power rating as relates to DC coupling to a microinverter, so long as its within allowable DC input voltage limits, i.e. presumably 60 cell modules, in theory the more aggregate solar power that can be harvested over time.

Also, as you have noted, because the vast majority of time the system is not operating at peak power levels, so in some sense, the greater the area under the curve even if clipping is fairly frequent. However, there is a tradeoff with respect to paying more for higher priced panels vs. how much lost overpowering is sacrificed due to "clipping".

At some point the cost outweighs the benefits of overpowering the microinverters (i.e. the increased area under the curve) is less than the potential would-be area "above" the curve. How the system is sized and cost optimized, for a particular location and azimuth, tilt angle, and a whole bunch of other relevant "efficiency" factors is also equally important.

 

[TeCKis300]

Ah, found a link to share my system - here

I got asked who my installer was and I forgot to share: Milholland Electric Inc. Contact Harry at 858.541.1097 and tell him Paul with the RAV4 EV sent you.

I researched and narrowed it down to 3 companies that gave me bids. Harry was by far the most knowledgeable and didn't try to play the smoke and mirrors game that I got through the other shops. He came out of the gate with a solid bid, and gave me options with equipment to tailor for my needs. Turns out, they are also the subcontractors to some other major 'solar marketing' companies so it's nice to work directly with the source. Harry was always prompt with every communication which I greatly appreciated and the install came out great.

Dsinned, I likewise am considering expanding my system because of how much we use the RAV compared to planned. We love the RAV so much, that we put every mile possible on it, between my wife and I. This is even with our daughter and inlaws in tow. All the while, our previously designated LX470 family hauler, sits quietly snoozing in the garage. This speaks volumes for how good of a well rounded car the RAV turned out to be.

 

[Dsinned]

Without shading or layout issues, string inverters still have a pricing advantage. Though if you factor in the replacement cost of the string inverter at ~10-15 years down the road, it may bring the price points closer. Sounds like your situation is ideally suited for the string inverters as you're even taking advantage of the waste heat! That aquatic setup you got there sounds pretty awesome.

I was able to get my system installed for ~$2.50 after federal rebate.

From a labor cost perspective, the AC style inverters install similar to string style inverters, and might actually be simpler yet. There is no roof assembly of separate inverters, and the associated extra connections between the panels/inverters, extra mounting of individual microinverters to the rail, and extra grounding of the inverter and panel independently. Then it's simple standard 10/12 gauge romex to the breaker panel.

Any way you do it, gotta love EV+PV.

TeCKis300, nice system. I like the way your monitoring display allows you to point the mouse at a particular panel to see all the electrical data for just that one panel.

Btw, one possible advantage of Enphase microinverters, still mounted beneath the PV panels (like yours), which provides a "shaded", cooler operating environment, is that they also can benefit by mounting to the roof rails. This is because they are mounted to very large metal mass (the rails), which in effect, act like an aluminum heatsink to conduct heat dissipation away from inside the electronic modules. This is better for long term reliability.

Did you install a solar production meter in your system? I am thinking about doing this using an Enphase "RGM", which greatly improves the accuracy of the measured power output from the array, but still uses the same ENLIGHTEN monitoring system. Does you system (or installer) provide your monitoring software services free of charge or is there some sort of subscription fee?

 

[TeCKis300]

TeCKis300, nice system. I like the way your monitoring display allows you to point the mouse at a particular panel to see all the electrical data for just that one panel.

Btw, one possible advantage of Enphase microinverters, still mounted beneath the PV panels (like yours), which provides a "shaded", cooler operating environment, is that they also can benefit by mounting to the roof rails. This is because they are mounted to very large metal mass (the rails), which in effect, act like an aluminum heatsink to conduct heat dissipation away from inside the electronic modules. This is better for long term reliability.

Did you install a solar production meter in your system? I am thinking about doing this using an Enphase "RGM", which greatly improves the accuracy of the measured power output from the array, but still uses the same ENLIGHTEN monitoring system. Does you system (or installer) provide your monitoring software services free of charge or is there some sort of subscription fee?

The per panel data is an interesting perspective. It is only available live and is not recorded for review.

To your point about heat sinking and dissipation...from the per panel data, I can tell that the corner located panels do run slightly cooler by 2-4 degrees. In turn, this allows them to run more efficiently and produce ever slightly more power. I don't disagree it may be a slight advantage to heat sink through the rails, but my locale has rather mild summers. Another potential factor to weigh for reliability is that an integrated inverter has less overall connections, and hence, less opportunity for connection corrosion and failures. I would weigh this more heavily if I were in a coastal property though. Don't get me wrong, I do like the Enphase system and considered that as the stronger choice.

My installation does include monitoring and a production meter, that is free of service fee. I may be wrong but it was mentioned to me that monitoring was a requirement for systems over 4kW to be eligible for the CA rebate. I think the ENLIGHTEN system had switched to a free monitoring service in recent years due to competition? Having a service fee in my mind would be very counter productive to a PV system ROI.

 

[jspearman]

Reading about the dirty panels got me on the roof with a power washer to clean off the generous coating of pollen that's been collecting these past few weeks. I usually just wait for a rain, but I wanted to see how much difference it would make. To my surprise, production dropped slightly, from around 94kWh to 91kWh. Probably a few more clouds today, but it was sad after all the hard work!!

 

[Dsinned]

I think the "RGM" (Residential Grade Meter) requirement applies in CA for larger (generally non-residential) systems over "30kW".

Enlighten solar output monitoring w/o an RGM meter, and therefore less accurate, is certainly adequate for most system owners to qualify for the CSI rebate. The accuracy of the output measurements internal to the microinverters is still fairly accurate; perhaps <5%. The CA CSI rebate has decreased significantly in recent years to only $200/kW (or $0.20/watt). I don't believe there is any monitoring "required" at all for small size residential systems. For the "PBI" rebate generally applicable to larger, commercialized systems, I think the meter's accuracy requirement is <2%. However, I think basic monitoring is essential for ANY system, and with Enphase inverters it is a total no-brainer.

I would like to upgrade my system to include an RGM to improve the accuracy, but this is entirely optional and voluntary on my part. It is also somewhat costly as I am finding out right now. The meter itself is several hundred dollars, then you need a way to mount it, in a waterproof enclosure for outdoor applications, which generally means PV homerun wiring modifications. Fortunately, this meter communicates with an existing Enlighten monitoring system via a Zigbee radio transmitter/receiver that generally cost under $100.

Btw, I just found out that my Mains AC service panel is inadequately rated to expand my system beyond a 17 panel/inverter array. I have a 100A panel, so the biggest circuit breaker I can add for the PV grid tied connection is 20A. This CB has to be no more than 80% of the PV system's maximum output amperage rating. Enphase specifies 17 inverters is the maximum quantity that can be strung together on the same AC branch circuit, which corresponds to a maximum output current of 15.3A.

Nevertheless, with a 17 panel system (4.25kW-dc) I should be able to generate more than enough power to zero out my electric bill, charge both EVs at home whenever I want, plus operate my central heating and A/C system as necessary to live comfortably throughout the year, ALL FOR FREE! :mrgreen:

 

[waidy]

[...important stuffs deleted...]Btw, I just found out that my Mains AC service panel is inadequately rated to expand my system beyond a 17 panel/inverter array. I have a 100A panel, so the biggest circuit breaker I can add for the PV grid tied connection is 20A, which has to be no more than 80% of the PV system's maximum output amperage rating. Enphase specifies that 17 inverters is the maximum quantity that can be strung together on the same AC branch circuit, which corresponds to a maximum output current of 15.3A.[...more important stuffs deleted...]

Just a note, that PG&E has program in which PG&E will cover service upgrades to PG&E lines and transformers caused by the purchase of an EV for a maximum of $2000. This is anything from anywhere from PG&E all the way up to your meter. You will have to pay for the upgrade from the meter to your panel (hopefully a short distance).

 

[miimura]

I think the "RGM" (Residential Grade Meter) requirement applies in CA for larger (generally non-residential) systems over "30kW".

Enlighten solar output monitoring w/o an RGM meter, and therefore less accurate, is certainly adequate for most system owners to qualify for the CSI rebate. The accuracy of the output measurements internal to the microinverters is still fairly accurate; perhaps <5%. The CA CSI rebate has decreased significantly in recent years to only $200/kW (or $0.20/watt). I don't believe there is any monitoring "required" at all for small size residential systems. For the "PBI" rebate generally applicable to larger, commercialized systems, I think the meter's accuracy requirement is <2%. However, I think basic monitoring is essential for ANY system, and with Enphase inverters it is a total no-brainer.

I would like to upgrade my system to include an RGM to improve the accuracy, but this is entirely optional and voluntary on my part. It is also somewhat costly as I am finding out right now. The meter itself is several hundred dollars, then you need a way to mount it, in a waterproof enclosure for outdoor applications, which generally means PV homerun wiring modifications. Fortunately, this meter communicates with an existing Enlighten monitoring system via a Zigbee radio transmitter/receiver that generally cost under $100.

Btw, I just found out that my Mains AC service panel is inadequately rated to expand my system beyond a 17 panel/inverter array. I have a 100A panel, so the biggest circuit breaker I can add for the PV grid tied connection is 20A. This CB has to be no more than 80% of the PV system's maximum output amperage rating. Enphase specifies 17 inverters is the maximum quantity that can be strung together on the same AC branch circuit, which corresponds to a maximum output current of 15.3A.

Nevertheless, with a 17 panel system (4.25kW-dc) I should be able to generate more than enough power to zero out my electric bill, charge both EVs at home whenever I want, plus operate my central heating and A/C system as necessary to live comfortably throughout the year, ALL FOR FREE! :mrgreen:

The Enphase RGM is a "Revenue Grade Meter" which means it's accurate enough for billing purposes. It uses a conventional meter socket, just like your PG&E meter does. The installation for this is equivalent to installing another meter to get E-9B (separately metered EV/CNG compressor) service from PG&E except it is metering power going out, not separately metering power going into your EV. IMHO, this is overkill for a residential and non-PPA solar system. You would be better served by putting that money into upgrading your panel and service to 200A. As Waidy pointed out, PG&E may pay for upgrading the service line up to your meter.

Actually, I'm surprised that you could get an EVSE and solar into your 100A panel at all. When I built my house last year, I had the electrician put in a 400A panel to accommodate two future EVSEs (currently wired as NEMA 14-50 sockets, one on each side wall of the garage), two solar branch circuits (240V 20A each) and a 240V 50A circuit for the oven. Almost every other circuit in the house runs off a 100A sub-panel.

 

[TonyWilliams]

Here's the Enphase link to my system:

http://enlighten.enphaseenergy.com/public/systems/Ukwf22392

 

[jspearman]

I was proud to read this morning that we in Arizona have finally passed New Jersey to have the second-largest amount of PV installed. Still way behind California, though. Most of the PV installed last year was individuals, ringing up 83MW of installs! We finally have some more utility-sized installs coming, but I love to see the distributed generation.

 

[Dsinned]

I know some ppl here on interested in getting a solar system now that a RAV4 EV is parked in their garage. Just wanted them to know that my solar installer, Petersen Dean Roofing and Solar Energy, is having a "warehouse" sale, while supplies last, this Saturday, April 13th. Any of their systems that usually sell for between $3.50 to $4.00 per watt, will be sold, fully installed, for $2.99 per watt. For example, a minimum size system, 1500 watts (sufficient to charge a RAV4 EV at least a couple times per week), will sell for $4485. Such a system, aka: PowerSaver Series 1500, regularly sells for $5999. That's more than a $1500 discount! Plus, if you purchase, you'll get a 30% tax credit (on your next tax return (2013). That means the net cost would be ONLY $3139.50.

It don't get any better than that!!! :mrgreen:

Here's the link for more information: http://powersaverseries.com/warehousesale.php

P.S. If you take advantage of this incredible sale, please tell them I (my real name is Dennis) referred you, and ask for Paul Beckman in Sales. Thanks!