My Nissan Leaf Forum

Was kind of surprised to see a variety of Costco solar panel systems online.
They seem to have a pretty nice 3750watt system with M215 micro inverters.
Comes with mounting hardware and price includes shipping.
15 250watt panels.
Still not sure what they mean by 3750watt maximum power per day.
And shouldn't it be more than 175kWh per month?
And is it really only sufficient for 1/2 the power needs of an average 1200sq ft house??















How does does this $11300 system stack up against some of the other systems discussed on this forum?

What kind of installation/permiting costs/etc are expected for an installation of a 15 panel system approx? I live in Southern California.

If I charge the LEAF on average 3.8kWh for 4 hrs during the night...wouldnt a 3750 watt panel system running all day cover the power used by my LEAF??

So tempting to install something like this, but I am not fond of ruining my lightweight clay roof that was installed on my house not too long ago, as it was quite a bit of $$ to install the roof.

FYI: My bill last month was 985kWh ($176.31)
My super off peak when I charge is at .17cent/kWh
My rates for the rest of the day is around .27cent/kWh
However in the summer my peak rates will be .60cents/kWh

While solar is a good idea for you, Elroy, this package from Costco is not. I'll break it down for you-

$12,203.99 cost (including tax) = $3.25 per watt. Plus you're gonna need...

$ 600 Creofix spanish tile roof stands
$ 255 Enphase trunk cables
$ 450 Enphase Envoy computer
$ 139 trunk cable stainless steel clips
$ 350 wire, junction boxes, conduit, breakers, etc
$ 300 average cost of permit
$ 168 tax on all this
$2,262 total for extras

$12,203.99 original cost
+$2,262.00 extra parts needed
$14,465.99 = $3.86 per watt for only materials

The lowest installed price in California for your size system is currently $3.69 per watt, all materials and labor included. But, that company is based in the Northern California bay area, and you live in Southern California. For 2012, in the entire state, the average installed price for a 3.75 kw system is close to $6.00 per watt (per the California Solar Initiative website). Two weeks ago in Castro Valley, I saw a bid by Solar City for a 3 kw system, and they wanted $6.67 per watt. Yikes! It's very surprising to me that the prices are still so high, because the material costs for a solar system have plummeted this year. It's sort of like when the price of a barrel of oil drops a lot, and the price of gasoline doesn't.

So you should look for a bid from a solar company for between $3.69 per watt and $6.00 per watt. For that, you should expect- 1) a complete system installed, all labor and materials 2) the installer to do all the paperwork and drawings for the building permit application, all paperwork regarding your utility rebate, and all paperwork regarding your new solar meter 3) an internationally known brand of solar panel (not Grape), made by a strong, non-Chinese based company that'll hopefully be around for the full 25 years of the panel guarantee.

If you can find a licensed contractor, with solar experience, who will do it for $4.50-5.00 a watt or so, go for it.

Good luck Elroy!

Good Info! I always thought with the good Costco Warranty I would be well protected with no hassles. However, in this case with the average PV system warranties..it shouldn't be an issue anyways. And is having only a 10yrs material and workmanship warranty the norm? Is 18% efficiency high end or just average? And yes it seems the cost of install here about equals the materials anyways.

And is having only a 10yrs material and workmanship warranty the norm? For the system as a whole? Yes.

Is 18% efficiency high end or just average? High end.

The average efficiency is between 14% to 16% for solar panels. But keep in mind, efficiency is primarily a smoke screen by solar companies so that they can charge higher prices. But a high efficiency 250 watt panel doesn't put out more power than a standard 250 watt panel, it just puts out the same amount of power with a smaller panel. It's quite unimportant if your panels cover 100 square feet less of your roof with high efficiency panels than with standard panels. Do you think anyone would ever notice or care? What you really need to know is- How much are you going to pay for each watt produced?

A 4 kw system with standard 250 watt panels is no different than a 4 kw system with high efficiency 250 watt panels. The standard system has 16 panels, the high efficiency system has 16 panels. The high efficiency panels will take about 25% less roof area, therefore they put out more power per square foot; but, they still only produce 4 kws, just like the standard panels. The important differences are- 1) a standard 4 kw system is much cheaper 2) a standard 4 kw system coupled with Enphase M215 inverters will actually outproduce a 4 kw system of high efficiency panels coupled with a DC inverter 3) you pay much more per watt produced for high efficiency panels than with standard panels.

With standard panels, you'll pay anywhere from $3.69 to $6.00 per watt installed, and with the high efficiency panels you'll be lucky to be below $6.00 a watt, and often the price will be higher.

The only time to consider high efficiency panels is when you have a small amount of roof area available for your solar system (remember, a high efficiency 250 watt panel is smaller than a standard 250 watt panel). Therefore, you can fit more panels into a limited roof area.

If you have enough roof area, as most people do, the high efficiency panels NEVER pay off better than the standard panels.

These Costco panels appear to be about 3.25ft x 5.3 ft.
Are those high efficiency panel dimensions?
If so, how do stock efficiency panel dimensions compare?
Also, with my 985kWh consumption for the month, what size system is needed?

I was looking at the data from a forum member's system:


It appears that even with a 6kw system, you will fall short especially at this time of year

These Costco panels appear to be about 3.25ft x 5.3 ft.
Are those high efficiency panel dimensions? No, that's the standard size

If so, how do stock efficiency panel dimensions compare? 2.5ft x 5ft

Also, with my 985kWh consumption for the month, what size system is needed? With south-facing panels, a 6.75kw system will cover all your consumption. But you would actually need a smaller system, from 5.5kw to 6kw, to reduce your bill to zero since you'll receive the solar benefits of time-of-use billing.

It appears that even with a 6kw system, you will fall short especially at this time of year. You stock up your excess solar credits during the summer with time-of-use billing, and use them during the winter.

Here is the forum member's system output for today...12/29/2012:
Today's total output: 8.97 kWh
Past 7 days: 47.3 kWh
Month to date: 244kWh

https://enlighten.enphaseenergy.com/pub ... /QDVT52503

So this is around a 7kW system with 31 panels I believe.
And yet I am consuming on average 26-30kWh per day....and this huge system would have only covered 1/3 of my energy needs today?

And for the past 7 days, you can see the average was under 7kWh per day.

Is this because of the time of year? And if so, it would seem it would be hard to go too big, considering this is 31 panels.
And out of 7kWh generated, That wouldn't even power the LEAF L2 charging for 2 hrs. I would need more than double that to charge my LEAF battery daily.

So this is around a 7kW system with 31 panels I believe.
And yet I am consuming on average 26-30kWh per day....and this huge system would have only covered 1/3 of my energy needs today?

Elroy, the numbers are down because it's been cloudy and raining in Roseville all month. Solar panels don't run on clouds or rain. Even without clouds or rain, panels have less production in the winter cause the sun is low, and more in the summer cause the sun is high.

If Con Edison has cheap baseline charges like PGE, and if they're 4,800 kwh per year like PGE, a good size system for you would be 4.25kws. It would produce 7,437 kwh's per year (facing due south), and therefore would reduce your electric bill comfortably into the cheap baseline electric charges.

I just noticed that his house is now producing electricity on the other side of the roof which was pretty much dormant earlier today. So perhaps he doesn't have a south facing roof? If so, how much difference would that have made in total output?
Still not bad, he will probably just about hit 16kWh for the day. That would have covered my 30 miles of driving/testing today.
As far as my whole household usage, I used 47.4kWh total yesterday. I am currenty in tier 2 of the TOU EV rate.

So perhaps he doesn't have a south facing roof? If so, how much difference would that have made in total output? Approx half of his panels face due east, and the other half face due west. He loses 11% of what he would have otherwise produced with due south facing panels.

Still not bad, he will probably just about hit 16kWh for the day. That would have covered my 30 miles of driving/testing today. The general benchmark is 4 miles driven per 1 hour of charging. So, your 30 miles driven was powered by 7 1/2 kwhs, not 16.