New Installation - Advice Needed

New Installation - Advice Needed

Today I got the engineering plan for my new Solar City PV install as well as some documents from the local electric co-op. I have a few issues that I hope I can get some advice on.

1. The electric company wants me to sign over my environmental credits to them. This made sense in the past when PV systems were being installed "for free", but I am paying for this entire system out of pocket (loan). They are distancing themselves from any and all maintenance of the PV system. This may be a standard concession, but it feels like a load of crap. Do I have any options? Am I overlooking a cost to the electric company that these credits are intended to cover? Signing these credits over to them allows them to claim "green" improvements to their system that they have not made.

2. The original size of the system was supposed to be 7.8KW (27 panels). The electric company does not want to size the system beyond 125% of estimated usage. Sounds logical. The problem is that I added a Tesla Model S75 to my energy needs a month ago, and this is not reflected in 90% of the usage reports that made up my estimate. Solar City made the initial estimate that produced the 7.8KW size using a rough estimate of Model S charging, but the electric company's estimate has dropped this to 6.8KW (21 panels). Since I cannot grow my PV array (Solar City will not add panels at a later date, but you can buy another system...), I have to get this right the first time.

3. I'm not a big believer in feng shui, but the panel layout on the engineering plan is asymmetrical and aesthetically, I don't like it. Yes, this is kind of stupid, but it's something I have hanging on the outside of my house and I want it to look nice. Adding 3 panels or removing 3 panels would fix it.

4. Along with the panels, there is no mention on the design plan about cable routing or conduit. The roof these PV panels will be mounted on is on the opposite side of the house from where the electrical panel is located. I really do not like the thought of conduit draped over the roof, but a roof penetration is not something to be taken lightly. I have a pitched roof (5/12) with concrete shingles. They say they will paint the conduit to minimize the unsightliness, but I would love to avoid external conduit as much as possible.

So my thoughts on 1, 2 and 3: Hold the credits as a carrot over the head of the co-op to get them to add 3 panels to the system. This fixes the asymmetry and gets me up to probably 7.5KW, which is closer to the original estimate.

As to the 4th, how hard is it to get a good roof penetrating install out of Solar City?

Gwgan | 6 November 2017

Maybe you need a sit down with your grid people. The green credits are yours and your estimated usage is what you say it will be. What if this were new construction without a history, or you were adding a pool heater and a heat pump at the same time?

Tesla-David | 2 June 2018

Where do you live? What you outlined does sound out of line with our experience in Edmonds, WA. I installed a 9.84 kWh (41 240 W panels) solar system initially in 2012, but added 3.36 kWh (14 240 W panels) in 2013 to offset our anticipated electric use to charge our new MS. However, this was done before we did weatherization repairs to our 1987 built home to reduce our energy demand. Over the past six years we have managed to reduce our energy demand each year, so that now we are producing ~200 percent of our electrical energy demand to run our all electric home and charge our two Tesla's (MS and now M3). We get all the energy credits, and through net metering, our electrical provider pays us $0.54/kWh and we pay them ~$0.10/kWh for the electricity we draw from the grid, and the cut us a check for $5,000/year for our excess Net Metered electricity. Additionally, I will get two PW2's installed in about two weeks, which will enable us to further reduce our reliance on the grid. Our electric provider did not impose any limits on our solar panel design. I unintentionally overbuilt our solar system, as I did not realize how much the energy reduction efforts would have on our total energy demand reducing our annual energy demand from around 12,000 kWh/year down to ~5,000 kWh/year. Our home was certified as a Net Zero Energy home by the International Living Future Institute in 2016 ( )

Based on your outline, it seems your electricity provider is draconian and backward in its approach. Solar City did not do our install back in 2012, as they were not operating in Washington State. We have been extremely pleased with our solar system installation. Not sure what you are asking in your 4th question regarding roof penetrating install?

sashton | 3 June 2018

@Tesla-David I read the article on your house with interest. I have to say I'm impressed with what you've done there - Congratulations!

I wish we could say our installation was as well planned as yours but the growth in our setup has been constrained by what we could afford each year.
We started with a 1000 year of watermill with every intention of using the wheel to power everything and never got round to setting up a micro-hydro system.
1) Installed a 2000L thermal store. This is heated by 18m2 of solar tubes. In retrospect I should have started down the PV route earlier and not installed thermal hot water/heating but we live and learn. It has reduced our heating oil consumption by 80% and has been in for 12 years with no issues yet.
2) We started with 4kWp PV 11 years ago. I was so glad I paid extra for the Sanyo (now Panasonic) HIT panels. They have outperformed all the subsequent ones we have used, especially in early morning and late evening. This was then expanded to 8 and then 11kW as we added the PHEV cars.
3) Bought a Chevy Volt. I know this isn't really the best forum for singing its praises but five years and 90,000 miles later it is still hasn't missed a beat. All short trips so less than 300 gallons over its lifetime is just insanely good. I wish I could say the same for the second one - VW Golf GTE but I can't. It has been the most unreliable car I have ever owned.
4) PW II. Now had it for 11 months. Loads of problems. WiFi connection to sensors failed regularly; It didn't like our original router (connection to tesla died regularly - so the app stops). Every time the FW was upgraded it introduced novel problems. We're now on 1.17.2 for a trial period and I have my fingers crossed. We were horribly misled by Tesla on the backup gateway with its release in the UK now over a year late and counting. Still, I have another PW II arriving this month and we'll see if the latest estimate for the UK backup Gateway (August 2018) is just another empty promise from Tesla.
5) Would love to buy a Model 3 and have had a reservation o/s for what seems like ages and last weeks announcement puts us just behind the second coming of Jesus.(RHD - UK). will probably have to settle for a Hyundai Kona EV or the Kia Nero EV, both of which will be here this year. I would have bought a Bolt but GM withdrew from RHD markets - doh! Now Trump has declared a trade war on Europe the Model 3 will probably be hit by a +25% retaliatory levy which also makes waiting more risky.
6) Bought a car charger that (in theory) can be set to charge the cars when the PW is full and we have excess power. Well, like the PW II, it has had quite a few teething problems. it works perfectly with the Volt but causes more issues with the VW.
...and I still haven't got round to restoring the mill wheel.

Tesla-David | 4 June 2018

@sashton, reading your narrative of your journey to sustainability I am most impressed, you have done a lot. Sorry to hear about your problems with the PW2, and hope we have smoother sailing, but am fully committed to integrate our two PW2's into our PV system. No problem singing the praises of the Chevy Volt, and happy to hear this car has really been reliable for you over past five years. I have friends who own Volts, and like them as well. I will see how well the PW2 work to charge our two Tesla's and will report back after we go operational. Sorry about Drumpf's stupid trade war, what an idiot. Hope you get a chance to pick up an M3 someday. We have been incredibly impressed with our M3, and believe it is indeed a game changer, especially its efficiency, and are averaging greater than 100 percent relative to rated range (310 mile).

BTW, I like your idea about setting up watermill and wish we had that capability here, but no stream access on our property. In Northwest Washington, our solar works incredibly well 9 months of the year, but underperforms from November through January, so having a mill wheel to provide that additional electricity to make everything work out would be great.

sashton | 4 June 2018

@Tesla-David If my geography serves me right we are even further north (UK) and the poor winter sunlight really kills us too. e.g. This January we only made 300kWh while May yielded 1.5mWh. Given that the Fronius inverters can be relatively safely overdriven I plan to extend the strings by 50% just for the November - February period next year. Our base load excluding cars about 600kWh/mo so we'll still be short so the next project may be a small wind turbine as we averaged 5.5m/s at 20m when I put up a trial anemometer last winter.
Like you we are migrating to our own water supply. There is a spring that used to supply the house. It is now pumped to a 10,000L holding tank but my wife will not let me connect it up until it has been tested for a year. So now, every month, I submit a sample to be tested for coliforms; heavy metals; pesticides etc. So far so good.

Tesla-David | 5 June 2018

@sashton. Your solar numbers are similar to mine, but we only produced 262 kWh in January of this year (averaging 325 kWh/ over last 6 years) and 1.839 mWh in May (new record high averaging 1.732 mWh over last 6 years). With the energy retrofits we have been doing our electricity demand keeps going down, and we only needed 254 kWh total for May, with only 87 kWh of that total to run our home last month (new record low), so most was for charging the two Tesla's. I have enough room on our roof to add another 3 kWh of solar, but that still would not be enough to cover our needs during Winter. Comparing our use to yours we are also similar, as we are averaging around 457 kWh/month excluding the EV charging (ranging from 245 to 880 kWh/month).

I also like your small wind turbine option, but understand that is prohibited here right now. We are trying to be a sustainable as possible. My wife wants to live in Hawaii during the Winter, but we haven't pursued that option yet. If so, going solar with PW2 with Cisterns, and M3 would give us what we need to easily cover our energy needs sustainably. Good luck hooking up your own water supply. It feels good living with a small footprint. Thanks for sharing your story. Very interesting.