AP Climate Solutions


Solar Equipment and Installation Basics - Scroll Down for My 2 Year Update

Just put your phone number into a Internet Solar Inquiry and "they" descend on you like yellow jackets at a picnic.

After being held captive in the living room through three presentations, waiting 4 months to be refunded the $500 "upfront, refundable starter, assessment" fee, I called an electrician we knew who had given us prior sterling service.  I asked him for a price to install solar panels with battery storage.  He said he couldn't beat the price Tesla Energy charged, and I should go with them.  

Tesla Energy had never called us during the yellow jacket swarm, so I called them.  After paying a $500 refundable assessment fee, they made one site visit to evaluate the roof.  Everything else was done over the phone, engineering, docu-signing the contract, and payment.  Upper management seemed somewhat disorganized and busy having a fire-drill, but the individual workers were superb.   The sales person was flexible.  I told her how much I wanted to spend and she designed a system that accommodated my budget.  It was OK to own, not lease, and to pay in cash.  Amazingly, other companies pushed back on these simple requests. 

Unfortunately, it did take 6 months to get the solar system in service, because they messed up on the re-roofing, which Tesla paid most of and my partner the rest.  Because of this delay I split my 2 principle payments between 2 tax years.  But that should be fine with the new Section 48 on Form 3468 allowing the deduction to begin in the year when the construction starts.  


During my research I determined 4 comparisons to make when evaluating the panels.

Efficiency The higher the percentage the better.

Energy Temperature Co-efficient / degrees F   The closer to zero the better.

Warranty: 10 year for material is normal, but 12, 15, and even 25 is available.  

Cost:  As of 2019 Mid-range was $3.30-3.67/watt

I found Tesla compared better on all these elements.  They were not the ones who told me to look for these comparisons.


How to determined the number of panels

First, I told Tesla the amount of money I had to spend and they designed a system with the number of panels plus 1 PowerWall for that amount.  The other 3 solar installers I interviewed argued immediately about the amount and would not consider designing a system for less than what they wanted to sell.  To me this was heavy handed and an immediate red-flag.

On my friend's current PGE bill, heating is with gas, and electric includes charging for an EV [electric vehicle].  His monthly average is 818 kWh for electricity.  The system Tesla suggested with the amount of money I gave them to spend would only produce 42% or 345 kWh per month with their panels which produced 325 w/hr.  They told me the roof could accommodate more panels though, and they could optimize our system to give 66% of the amount of electricity currently being used.  This was a more cooperative sales approach for me, and I authorized another 8.5K to allow more solar power be produced.  (vary the w/hr in the equation according to your chosen panel)

To figure out how many panels you should consider:     ((1 panel @ 325 watt / hour) X (6 hours sunshine / day X 30.5 days / month)) = 59.4 kWh / panel 

The final system installed contains:                                  (13  panels X 59.4 kWh / panel) = 773,173 kWh / month

or 94% possible net metering under perfect conditions.   Tesla factored in shade and weather/seasons lowering their output guarantee to 66%.  

Net Metering

The first home owners who installed solar were just as grid dependent as people without any.  The only benefit solar owners got was net metering.  The value of net metering depended on whether or not you were able to use all your energy credit before your utility company zeroed out your account each year.  Net metering returns were also dependent on the retail verses the wholesale price of a kWh, because solar arrays owners had to sell their kWh to their only customer, their utility company, and buy kWh from their only supplier, their utility company.  Yes, the electric company ruled.

That all changed with...

 The Battery.

Now solar array owners are not mercilessly tethered to their utility company, and most importantly enjoyed continued power when their neighbors are in the dark. 

I bought the Tesla Powerwall because it was guaranteed to withstand loading and discharging everyday in order to send its full load (or what we determine) of electric charge to the grid thereby maximizing net metering benefits.  Alkaloid and golf cart batteries may not be capable or guaranteed for this use and should be evaluated carefully.  I also bought the Tesla Powerwall because it was simply more aesthetically pleasing to look at than a stack of alkaloid or golf cart batteries.  Finally a Tesla app to download onto a cell phone allows grid discharge scheduling changes when necessary, and can be done even away from the house.

In California, where we live, if you have an EV, the utility company PG&E has different kWh rates dependent on the demand for electricity.  This arrangement allows us to maximize net metering benefits by sending electricity during peak time, 2-9 PM, when we earn .47 per kWh in the Summer, and use grid power not battery power during the night, when it cost only .13 per kWh.   During our now regular fire season when outages were more likely we can change this schedule so the battery would always be fully charged and available for an mandatory outage . 


The Electric Quantity Guarantee

I do not know if all solar companies give the solar generation quantity guarantee for their installation.  But during our evaluation phase Tesla determined 66% of our usage would be met by the number of panels, their arrangement on the roof, and amount of sunshine expected to shine on them.  If we do not realize their estimate they write an annual check to compensate.


July 14, 2021 - How'd It Go

Now 2 years later the San Francisco East Bay area has had several planned PG&E fire prevention power outages, but my partner was only without power once.  We resolved that by adjusting our battery usage on our cell phone app so more charge was saved for such events.  No more participation than that adjustment was required.   Oh, and he asked his neighbor to cut his tree a bit.  It had grown higher than both house roofs and was not a aesthetic problem to trim.

The details of our new PG&E plan, NEM2MT B, arrives in a separate mailing from the bill.  It's impressive!  Multiple pages (13+) dissect, analysis, scrutinize, and justify our contribution and extraction of power from the grid.  I don't read it.

Only when I decided to do this update, did I, with the help of a PG&E Solar Department rep., go for the deep dive into the numbers.  1(877)-743-4112.   The house is on the EVA/NEMPS schedule, because of both solar panels and electric vehicles.  The cost of kWh depends on the time of day/night power from the grid is used.  In California the most expensive power $0.562 cents is in the Summer time during the high usage period, and the cheapest power $0.144 cents is between 11 pm and 7 am.  

Cut to the chase the DETAILS of the BILL The only page you need is the one with Usage and Generation Summary with the True-up History Summary.  Divide the total “E84 BL Charges” by the total “Billed Usage.” This is your net usage and cost for that time period without taxes. The result is your cost of electricity per kWh. 

By dividing the E84 BL CHG by the Billed Usage you get kWh average cost.  You might be interested here in taking a detour to the Electric Vehicle page and put that average cost of electricity into the gasoline to electricity equation.  I changed variable "C" from .12, the grid nightly rate when EV charging is most likely, to .08 the real cost of the kWh at the house. Our cars are now getting 172 miles to the "virtual" gallon of gasoline.

Also on page 2 of the PG&E Bill Details the “Grid Electricity Usage” column shows how much you have to rely on the grid. In our case while we had to use 6,908 grid kWh in one year.  Those kW were mainly used during the night when the rates were lowest.  During the day we were able to sell back 2,751 kWh, shown in the next column "Exported to the Grid."  If we value these kWh by the average cost of "time of day" electricity from the grid, $0.29 kWh, in our case the solar panels generated $798 for the year.  BUT the rate set by the California Public Utilities Commission allows them to pay only $0.02 -.04 cents for a kWh.  A fair price for the electricity would have paid all the interest I charged my partner for the cost of the panels, unfortunately life, when corporations run Public enterprises, is not fair for the public.  So I called Tesla and after several false starts talked to Anna, a longtime Tesla employee and non-assuming multimillionaire working for fun.  Anna clued me in on an evidently too obscure webpage for other employees or me to know about on Tesla's site.  Mobile-app describes a configuration called Self-Powered that first powers our needs before sending any power to the grid.  Already we're seeing improvement in solar to grid use.   Anna also shared the real phone number for Solar+Powerwall help  1(877)961-7652 #2

Regarding our Tesla contract and the solar panels performance.  On July 9th, we passed our 2nd year anniversary and could evaluate if the system was preforming as promised.  Our Tesla contract guarantees our solar panels would supply 10,757 kWh by the second anniversary. Looking at the Tesla App under Lifetime Energy the solar panels produced 12,236 kWh.  Unfortunately, I didn't catch that the final installed system was guaranteed to produce only 10,757 kWh basically 50% of my partner's usage.  BEWARE:  The contract was written with a particular kWh not the 66% expectation that the sales department alluded to.  While the solar panels exceeded their contract they did not give us what we thought we would be getting.  Regardless we are happy.  We have reliable energy during power outages, no maintenance energy production, and for me interest and rolling forward my tax credit a third year.  Most of all we were happy we've eliminated a considerable portion of our carbon footprint.


I see only one adjustment that I think would be fair so I wrote to a letter to PG&E Customer Service.  Hey! He really exists.  His name is Mike Barnett  I've asked PG&E to create a rate option for people who own both solar generating and electric vehicles.  Currently the only rate available, and it was automatically assigned to my partner, benefits those who charge their EVs at night.  But with solar we try to do all electrically demanding activities when the sun is shining.