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Residential Solar System - PV to EV

NigelM

Recovering Member
Apr 3, 2011
13,386
560
Northern Virginia
A couple of members asked about the solar system on our house, so here goes:

We talked to 3 different companies and got conflicting advice, so choose your company carefully, the most professional and the one who volunteered to do all the paperwork was Eco Technolgies Inc here in Sarasota. They took my last 12 months utility bills and worked out a 'net zero' system for me.

We did not want battery back-up as that would have required about 35-40 marine batteries (read big! and cost about $130 a piece) which would need to be replaced every 3 years. The 'net zero' system requires a bi-directional electricity meter and in Florida the utility companies are obliged by law to provide one on request. The charge for installing the meter was $400 but the paperwork and hassle to get it done was something else - we were really happy to have a good company taking care of things for us. (The power company really didn't seem to want to be helpful - OMG!)

We produce too much electricity during daylight hours, so the bi-directional meter runs backwards giving us a 'credit' and when we stop producing power (at night) the meter runs forwards as normal using the 'credit' we built up during the day. Some months we use more power than others (we have no heating here, but we do run the AC almost all year) so the target is to 'net zero' by the end of the year; some months I will have a small electricity bill (last month $7.04) and it looks like this month (being sunnier) the utility company will owe me about $20.00.

Spec's: PhotoVoltaic Module System - Total System Size - 19 kW System includes: (100) SunTech STP190 Modules and (100) EnPhase Micro Inverters.

Note: PV systems require inverters and you can run about 13-18 panels through one of the "old-style" inverters. These inverters weigh 30-40lbs each and we would have needed 6 of them about the size of a small suitcase. They have to be wall mounted and ideally indoors or in a weather resistant cabinet outside. However, if there is a fault on one PV panel you may never know and you wouldn't know which panel was the problem. This is why we went for the micro inverters, one on each panel, and about the size and weight of a hardback book. They have a NEMA 6P rating which means they will operate even underwater and we could fit them under each panel on the roof. There is a connection to my home pc where I can see the perfomance and power output of all panels and a built in alert system should one of them not be producing properly. (For more on this sytem, see my post here)

Cost: $117,342 including taxes, installation etc. There is a 30% Federal Tax deduction so the real cost is less. Previously we were paying about $5,000 a year in electricity bills and now we are adding EV's that would have increased somewhat. I know the payback would still be about 16 years but the reality is a great sense of freedom and the house value has increased by more than $100,000. Now we also managed to finance this work through my bank for 0.75% so and the return on investment runs about 6.25% (tax free!) annually so I can argue it makes financial sense also. The truth is that you don't make this sort of investment expecting a 5 year payback but who buys a Roadster on that basis? :wink:

One last point: we were obliged here (this may well vary by State) to add $1,000,000 liability insurance to our current house policy. The cost for us was about an extra $100 per year.

Here's some pics:

Racking and inverters (tip; we set it as close to the roof as possible to prevent wind issues - this is hurricane country after all!)
racking 2.jpg
racking.jpg


Starting the install
install.jpg
install 4.jpg


Job half completed
install 2.jpg
install 3.jpg


Final look (the excess racking was trimmed off to give a more aesthetic look)
complete.jpg
 
Last edited:

vfx

Well-Known Member
Aug 18, 2006
14,790
47
CA CA
Truly awesome. Who determines the increase in home value? Seems like no one wants to commit to that.
 

Tommy

Member
Mar 3, 2010
882
3
The great OC
Really helpful information. Thank you!

I saw on another thread you were starting to look into solar and as you are in CA you should browse CA's California Solar Initiative Program site if you have not done so already. The link I've posted is the calculator for the utilities rebate, also useful for comparing the different manufacturers, equipment, solar orientation, etc. Look around the site's home page as there is a lot of info regarding solar. There is also a spreadsheet that lists every solar system installed in CA under the program and is very detailed: company that did the install, manufacturers and $ paid for the system. Very helpful to check if you are getting a fair price and who the "big" installers are.

Anyone else in CA considering solar, this is a great reference site to begin your solar research.

CSI EPBB Calculator
 

bonnie

I play a nice person on twitter.
Feb 6, 2011
16,429
9,928
Columbia River Gorge
You've inspired me, Nigel. I have two contractors coming in the next week to give me an estimate. I've pulled my kWh history for the last couple of years and believe I'll need a slight smaller system (probably around 13kWh) - but we'll see what they have to say.

Thanks!
 

SByer

'08 #383
Oct 23, 2007
1,068
5
Cupertino, CA
Yes, and up here in northern CA, you'll find that getting PG&E to hook you up is a relative breeze. At least it was a couple of years ago when we had our system put in. Note that going with the higher efficiency panels is more expensive up front, but usually ends up paying off faster.
 

NigelM

Recovering Member
Apr 3, 2011
13,386
560
Northern Virginia
Bonnie, depending on the elevation of your roof you may need to over-spec the system slightly. In our location we needed to be a perfect south west but the roof just didn't allow it; given that the cost of rotating the house even a few degrees was prohibitive we just added an extra panel or two more than we would otherwise have needed. If your contractors are good they will come with compass and engineer...in any case they should tell you that an engineer will come to take accurate measurements, angles etc.

If you have any questions, feel free to PM me.
 

dsm363

Roadster + Sig Model S
May 17, 2009
18,279
160
Nevada
My parents are looking to get a 2.4kW system installed (10 panels), 2 solar attic vents and a solar water heater. I realize this is a small system and their house is around 4,000 square feet. What do you look at on your utility bill to figure out how much of your home's power this will cover (simply the kWh used per month)?
 
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DrComputer

TeslaClubLA President
Jan 29, 2009
1,169
469
Sherman Oaks, CA
It all depends on how your parents pay for power. If you are in an area with tiered rates, than many people want a system just to keep them out of the top (most expensive) tiers. If you are in a flat rate area, then it is a cost/benefit calculation. How much the initial outlay versus the estimated payback time.
 

dsm363

Roadster + Sig Model S
May 17, 2009
18,279
160
Nevada
Thanks. They're in Indiana so I believe that's a flat rate area with Duke Energy. I'll try and find out. They're doing it more for the environmental aspect and to reduce their bill a little bit.
 

marco2228

Roadster Signature #34
Nov 19, 2010
211
55
Cologne/Bremen , Germany
Nice article...
so in the US, you pay or get paid the difference of the amount you put into the grid and the amount you take out of it? You don't get a bonus because you generate electrical power out of regenerative energies or did i read over anything?

I'm from Germany and we installed a PV System in 2009.
We are charged 0.18 - 0.2 Euro per kWh we use and get 0.43 Euro per kWh for the first 30 Kilowatt peak of the plant, 0.4091 Euro for the part from 30 to 100 kW peak and 0.3958 Euro for that what is generated above the 100kWp.
So we get much more, than we have to pay, because it's a "green" energy.
That thing runs really well, at the moment we are almost 10% above calculations.
 

NigelM

Recovering Member
Apr 3, 2011
13,386
560
Northern Virginia
Nice article...so in the US, you pay or get paid the difference of the amount you put into the grid and the amount you take out of it?

In principle yes, but I can only confirm that for our power company here in my area. Many laws in the U.S. vary from state to state.

You don't get a bonus because you generate electrical power out of regenerative energies or did i read over anything?

No we don't; at least not in Florida (the Sunshine State!!) although there may be local incentives in other states. We get a 30% tax credit on a Federal level and the admiration of our friends.... :wink:
 

SByer

'08 #383
Oct 23, 2007
1,068
5
Cupertino, CA
Nice article...
so in the US, you pay or get paid the difference of the amount you put into the grid and the amount you take out of it? You don't get a bonus because you generate electrical power out of regenerative energies or did i read over anything?

Oh, in most places in the US it's far worse than that - in a lot of places there is an extreme dis-incentive to generate anything beyond that which gets you to a zero bill during your 'true up' period (a year, here). If, at the end of the true-up period, the electric utility owes you money, well, too bad, shine on (they don't have to pay you anything). Here in northern California, with time-of-use pricing, it's easy to get to that $0 mark at the end of a year with a system that generates only about %70 of your power.

It's incredibly stupid, really, because it means there are lots of solar installations which could easily have been bigger or used higher efficiency panels to put more into the grid, but that didn't make financial sense to put in that way.
 

marco2228

Roadster Signature #34
Nov 19, 2010
211
55
Cologne/Bremen , Germany
Oh, in most places in the US it's far worse than that - in a lot of places there is an extreme dis-incentive to generate anything beyond that which gets you to a zero bill during your 'true up' period (a year, here). If, at the end of the true-up period, the electric utility owes you money, well, too bad, shine on (they don't have to pay you anything). Here in northern California, with time-of-use pricing, it's easy to get to that $0 mark at the end of a year with a system that generates only about %70 of your power.

Wow, i didn't expect that.
But on the other hand Nigel sais, he will have saved the investment costs in 16 years, thats not too bad.
 

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