GM Volt Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
4,405 Posts
Discussion Starter #1 (Edited)
Specs:
64 x Astroenergy 310w PV panels
32 Solar Edge Optimizers (one feeds two panels)
1 Transformerless Solar Edge SE20KUS-480v 3ph 'Smart + Rapid Shutdown' inverter.
DynoRaxx flat roof ballasted mounting system.
3,802 lbs of 2x8x16 concrete ballast blocks
0.060" heat weld TPO white roof re-surfacing with insulation layer.

Total cost (roofing alone was $38,000) was $31,000+$38,000 = $69,000 including all labor, permits, taxes, mistakes, unnecessary steps, unused material. Cost of solar specific supplies $19,500. Total after Fed incentive = $48,300

Production is theoretical at this point: Per NREL calculator - 30 MWh per year.
But due to our Demand-based TOU which can hit $17.32 per kW, the monetary savings should be close to $10,000 a year.

Would I do it again? No. Our city is extremely incompetent and difficult to deal with.

Will report back with actual December results since it fired up Dec 1, 2017. This is the lowest production month and the panels are optimized for June/July/August when the highest tariffs are in effect. These months could save $1500 each unless the tariffs change.
 

·
Registered
Joined
·
1,680 Posts
$38k for re-roofing? Was it just a good excuse to re-roof anyway? A friend of mine is a solar installer. He has written articles in the past about how municipalities in the U.S. could and should be streamlining permits and inspections to lower the cost of installs.
 

·
Registered
Joined
·
335 Posts
Assuming it is residential - that's pretty big. Congrats.
I pulled my own permit as well and that was an unpleasant experience...
 

·
Registered
Joined
·
347 Posts
Wow, that's a huge array. I think some of your numbers might not be correct. I think the total estimated electricity production should be 30 Mwh/year. It appears that you live in Corona CA, so I think your utility is Southern Calif Edison. SCE requires their solar customers to use a time-of-use rate schedule. I believe this link below is the applicable rate schedule.

https://www.sce.com/wps/portal/home...syq-hqdvTtaZJw!!/dl4/d5/L2dBISEvZ0FBIS9nQSEh/

SCE, like many other utilities are facing a crisis with profits dwindling due to increased residential solar. To combat this trend the Public Utility Commssion allowed them to require solar customers to use a TOU rate schedule. These schedules charge according to the time the power is used. In order to offset the impact of solar on their profits these TOU schedules change the traditional peak period from daylight hours to periods where the sun is just rising or falling. Note the SCE schedule shows peak rates between 2-8 PM. That's when the power you are producing is worth the most. Unfortunately, the sun is waning during that period. This has a two pronged effect, it minimizes the impact of your solar production during off-peak hours and imposes their highest rates on you when the sun is down. I think the power you produce during the 2-8 PM peak period will offset power drawn from the grid on a Kwh to Kwh basis during this period. So if you produce more power than you use during this period you are OK. If not I believe you can trade power produced during off-peak time which corresponds to the most productive time for your solar. Unfortunately, every Kwh produced during this period is worth a lot less so it will take a lot more production to offset your evening usage during the 2-8 PM peak period. Any power you produce over your total yearly usage appears to be purchased by SCE at a wholesale rate of only 9 cents/ Kwh.

If this sounds complicated, it is. The bottom line is these new TOY rates have made it really difficult to figure out the return on investment. One thing is certain ROI is worse than before. This leads me to think your ROI estimate of $10K/year may be a bit optimistic.

What I did to offset the negative impact of the new TOU rates was to include a storage battery. The battery allow me to store unused solar produced during the day and use it at night instead of drawing power from the grid when it is the most expensive. I don't know if there's any money left in the program but California was giving a very generous rebate on batterys. You solar installer should have told you about it, but if not here is a description.

https://news.energysage.com/california-energy-storage-incentives-sgip-explained/
 

·
Registered
Joined
·
4,405 Posts
Discussion Starter #5
This is a 8000 sq ft commercial flat roof building.
For businesses using SCE, as of July you are forced into a Peak Demand TOU plan.

Example.

Let's say your charge for summer kWh averages .17 and you consume 7500 kWh a month. That's $1,275 for actual TOU power.

But your bill is $1900. Where is the rest of the money? They charge up to $17.32 per kW of your peak demand. This is not kWh, it's peak draw during the month. So if you plug in an EV, and it's a super hot day, and your air compressor turns on the same time the EV + AC + compressor + normal power use for lighting and computers = 36 kW for 15 minutes, on 1 day of the month. That adds $625 on top of your power usage. Luckily, solar power produces the most kW during this 'perfect storm', or about 17.5 kW peak reduction. So you instantly get a $300+ kickback against the Demand Fee, and then you also reduce the kWh's you consume also.

When you look at the Demand Graphs, you see they are of short duration. So you aim you panels for the summer afternoon.
 

·
Registered
Joined
·
4,405 Posts
Discussion Starter #7 (Edited)
I'll try to get some pics today. Yesterday it peaked at 10.x kW about noon. But the panels are set for summer operation, and there were light clouds.
 

·
Registered
Joined
·
4,405 Posts
Discussion Starter #10
You've got to be kidding.
Nope. I dropped my electric use from July 2016 to July 2017 by 22% but my bill went up 8%?

I had to look carefully to figure out why. There is an extra line item for "Demand" which added $554 to kWh's used. That was because one day in July, we peaked at 32 kW draw for 15 minutes, and it's $17.32 each.

Let's say you have coffee shop that has 2 employees and is 400 sq ft.
You put in a 32 amp 240v EVSE for your customers.

The first time somebody plugs it in during a new month, it adds $133 to your monthly bill even if it's only one time, and only 15 minutes. This does NOT include the power you use, only the peak draw. You must also pay for the power.

California is not a 'green' state in reality, just image. $1000 tax on solar installations, extra registration fees for EVs, most the ZEV budget is Hydrogen and Overhead.
 

·
Registered
Joined
·
11,416 Posts
Nope. I dropped my electric use from July 2016 to July 2017 by 22% but my bill went up 8%?

I had to look carefully to figure out why. There is an extra line item for "Demand" which added $554 to kWh's used. That was because one day in July, we peaked at 32 kW draw for 15 minutes, and it's $17.32 each.

Let's say you have coffee shop that has 2 employees and is 400 sq ft.
You put in a 32 amp 240v EVSE for your customers.

The first time somebody plugs it in during a new month, it adds $133 to your monthly bill even if it's only one time, and only 15 minutes. This does NOT include the power you use, only the peak draw. You must also pay for the power.

California is not a 'green' state in reality, just image. $1000 tax on solar installations, extra registration fees for EVs, most the ZEV budget is Hydrogen and Overhead.
Words fail me right now. :(
 

·
Registered
Joined
·
4,153 Posts
The first time somebody plugs it in during a new month, it adds $133 to your monthly bill even if it's only one time, and only 15 minutes. This does NOT include the power you use, only the peak draw. You must also pay for the power.
If you haven't contracted for that demand, yeah. Switch to a plan without a Demand Charge. Also switch to a plan without a Peak Day option. You'll pay a couple pennies more for each KWh, but there are ways to not be surprised if that's what's more valuable to you. Don't just look at the off-peak price and say "yay! I'm paying $0.203 per kwh instead of $0.218!"
 

·
Registered
Joined
·
4,405 Posts
Discussion Starter #13 (Edited)
If you haven't contracted for that demand, yeah. Switch to a plan without a Demand Charge. Also switch to a plan without a Peak Day option. You'll pay a couple pennies more for each KWh, but there are ways to not be surprised if that's what's more valuable to you. Don't just look at the off-peak price and say "yay! I'm paying $0.203 per kwh instead of $0.218!"
It's mandatory to have a TOU Demand plan since July 2017 when you are a business with Net Metering (solar) in California, or if your peak use ever hits 20kW.
 
1 - 13 of 13 Posts
Top