Here in SCE territory you get wholesale buy back which is about $.03 per kw. Best to use all you produce.
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Can you buy too much Solar?
- Thread starter d21mike
- Start date
Yes, you can buy too much, IMO. But it depends on your local utility and your goals.
If your goal is to net out at a zero bill for the year you want to oversize by a few percent to account for degradation over the years.
In Nor CA PGE requires you to pay a minimum $10 per month fee to connect to the grid.
So you really want to slightly undersize since you are paying that $10 no matter what.
Over producing gets you just 2-3 cents per kwh
If your goal is to produce as much solar as possible...you should install the extra panels at your neighbors house.
If your goal is to net out at a zero bill for the year you want to oversize by a few percent to account for degradation over the years.
In Nor CA PGE requires you to pay a minimum $10 per month fee to connect to the grid.
So you really want to slightly undersize since you are paying that $10 no matter what.
Over producing gets you just 2-3 cents per kwh
If your goal is to produce as much solar as possible...you should install the extra panels at your neighbors house.
My utility’s net metering credits don’t expire thankfully.
The wholesale buyback is only for excess kWh. It is possible to have a dollar credit balance due to TOU differentials while you are still a net kWh consumer. AFAIK, all major utilities in California will wipe out that credit balance at annual true-up. If you are on a CCA (Community Choice Aggregation), most will pay out your dollar credit balance due to TOU differentials at their retail generation rates. PG&E will still wipe out your transmission and distribution credit balance.
groovidad
Living the Dream!
We "oversized" our system to 141% of estimated usage. That was the max our utility would allow by using 120% of our previous year's usage plus an allotment of 3000 kWh for a newly purchased Tesla.
Going into it, we knew it wouldn't be sufficient because at the time we only had the usage of one out of three Teslas represented on the electric bills. So while they predicted we would cover our usage 141%, we've only covered it 90% since the beginning of 2019 and only about 75% since the system was turned in September 2018. Fortunately, we've had credits (negative balance on the electric bill) almost every month since March and our credits roll over and don't expire. Unfortunately, the credits will probably only get us through November or so and we'll be drawing a lot from the grid December through February. We'll be contacting Tesla to see if we can add another 4 kW or so but we covered most of the roof with the original system and the remaining roof faces northwest. We are also considering purchasing solar from a nearby solar farm to offset the rest of our usage. While solar farm production wouldn't help us in an extended outage, it would have much better production than any panels we install on the northwest-facing roof.
Most likely your usage will increase in the future, so I would oversize your system if possible.
Going into it, we knew it wouldn't be sufficient because at the time we only had the usage of one out of three Teslas represented on the electric bills. So while they predicted we would cover our usage 141%, we've only covered it 90% since the beginning of 2019 and only about 75% since the system was turned in September 2018. Fortunately, we've had credits (negative balance on the electric bill) almost every month since March and our credits roll over and don't expire. Unfortunately, the credits will probably only get us through November or so and we'll be drawing a lot from the grid December through February. We'll be contacting Tesla to see if we can add another 4 kW or so but we covered most of the roof with the original system and the remaining roof faces northwest. We are also considering purchasing solar from a nearby solar farm to offset the rest of our usage. While solar farm production wouldn't help us in an extended outage, it would have much better production than any panels we install on the northwest-facing roof.
Most likely your usage will increase in the future, so I would oversize your system if possible.
While everyone is thinking about over sizing, I am cheap and want to undersized it a tad.
I like the smaller 3.8 kilowatt Tesla is offering. On average the small size from what I've read in the forum will product on average 15 kilowatts a day. Web site listed at 12 to 19 kilowatt a day. I need 20 to 22 kilowatt for that is my normally daily energy usages. I figured for 10k or 7.5 k after incentive or 2.63 per kilowatt. It's affordable. I am on TOU. My utilization is 20% peak at .48 per kilowatt, 30% off peak at .24 cent per kilowatt, and 50% super off peak at .13 cents.
This small system will cover my normal peak time usages. At night time, I will pull from the grid to charge my car at .13 cents.
My average monthly bill is 110 to 120 ish. Am I under-sizing it to much?
Do you mean 3 cents per kWh?
System sizes are measured in kW (kilowatts). These are the right units for that.
Do you mean kWh (kilowatt-hours) here? If something has a draw of 6 kW for 1 hour, it has used 6 kWh. Ditto for a 6 watt device for 1000 hours.
Yes - Tesla is marketing the three solar size system. I am referring to the smaller 3.8 kilowatt hr system. Most appliance don't draw 6 KW. If you are thinking about charging your car sucking in 7 kilowatt/hr that's a different story. I'll pull that from the grind at night time on super off peak rate.
I don't fulling understand the wholesell of 3 cents buy back from SCE.
How does this work?
Currently I am on TOU without solar yet.
Summer rate per kilowatt is:
peak 2 pm to 8 pm = .48 cents
off peak 8 am to 2 pm = .24 cents
super off peak 8 pm to 8 am =.13 cents
Let say the 3.8 (small tesla system) can generate 3.8 kilowatt per hour.
If you use under 3.8 during sunny day, that's all good. Assuming you are producing 3.8 kwh.
If you use over the 3.8, it pull from the grid. The different of going over reflect the time you use and based on the TOU rate as listed above.
Let say you produce more then you use and have a credits.
The credit is only a 3 cents per kilowatt that SCE give back?
What if I using over my 3.8 kilowatt hour during peak time of .48 cents per kilowatt?
The credit will offset the .48 cents by 3 cents?
I thought it's reversing your meter (net metering). Your smart meter has two program ID 082 and program ID 071.
082 is the lifetime meter usages.
071 meter reading is giving back to the grid from solar panels.
If net metering is use to off setting the usage than the TOU rate cost is non factor. Right?
I am waiting for my install so I am basing this on my conversation with the SCE Customer Support Person.
I am the TOU-D-B. See rates below. I requested to keep the plan that I am grandfather until I think 2022. New plans are like 2 rates with peak either 4-9 or 5-8.
My understanding is that I accumulate credits based on when I add them.
Example:
Solar is mostly 10-2pm which is 16 cents. So I would be "banking" credits at 16 cents per kWh. However, whatever credits I add between 2-4pm or maybe 2-5pm I would be producing credits at 48 cents per kWh. Then when I use the credits they would be used at the rate at that time. Say I use them at super off-peak 10 cents per kWh then I would get a lot more kWh at my off-peak rate since I am using them at a lower cost than I created credits for them. I.E. The credits are based on the cost when you use the credits.
NOW.... Annually there is a true up. Meaning that if I accumulated more kWh credits then I used they would be purchased from me at the wholesale rate of 3 cents per kWh. This is a bit confusing because it is no longer based on when I added them but that is what I was told.
You should call your provider to check if what I am saying can be confirmed by a different person. But I am on SCE so they may also be different if you are not with SCE.
========================
SCE TOU-D-B:
Highest Rates: Weekdays 2-8 p.m.
Daily Basic Charge: $0.50 per day
Minimum Daily Charge: None
Baseline Credit: None
Summer Rates
Summer rates apply June through September. Rates are per kWh.
Weekday Summer Rates
Off-Peak: 16 cents from 8 a.m. to 2 p.m., and 8 p.m. to 10 p.m.
Super Off-Peak: 10 cents from 10 p.m. to 8 a.m.
On-Peak: 48 cents from 2 p.m. to 8 p.m.
Weekend Summer Rates
Off-Peak: 16 cents from 8 a.m. to 10 p.m.
Super Off-Peak: 10 cents from 10 p.m. to 8 a.m.
Winter Rates
Winter rates apply October through May. Rates are per kWh.
Weekday Winter Rates
Off-Peak: 15 cents from 8 a.m. to 2 p.m., and 8 p.m. to 10 p.m.
Super Off-Peak: 11 cents from 10 p.m. to 8 a.m.
On-Peak: 24 cents from 2 p.m. to 8 p.m.
Weekend Winter Rates
Weekend Off-Peak: 15 cents from 8 a.m. to 10 p.m.
Super Off-Peak: 11 cents from 10 p.m. to 8 a.m.
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Akikiki
A'-Lo-HA ! y'all
Quickstart, you said, "
If net metering is use to off setting the usage than the TOU rate cost is non factor. Right?"
That's to general a statement to make. a person/home can have/use net metering and still be on ToU.
And ToU is like saying, I own a truck. Different sizes and different flavors. Time of Use does not define what its actual rates are, they are not always the same. I looked at moving to ToU here a couple of years ago, when they offered it. As I recall, the peak was about 40-45 cents a kWh, and off peak was 22-25 cents. Was no bargain or practical.
If net metering is use to off setting the usage than the TOU rate cost is non factor. Right?"
That's to general a statement to make. a person/home can have/use net metering and still be on ToU.
And ToU is like saying, I own a truck. Different sizes and different flavors. Time of Use does not define what its actual rates are, they are not always the same. I looked at moving to ToU here a couple of years ago, when they offered it. As I recall, the peak was about 40-45 cents a kWh, and off peak was 22-25 cents. Was no bargain or practical.
"3.8 kilowatt hr system" makes no sense. You mean a 3.8 kW system?
"7 kilowatt/hr" also makes no sense. Watts are already joules per second, so joules per second per hour makes no sense. Are you talking about a 7 kW load?
Let's not get too hung up on this. Tesla offer small/medium/large system rent or own.
Small is 3.8 kW system basically it's a 12 panels at 300 ish watt panel and within an hour it can generate 300 watt hr per panel.
If you really want to be technical it's 315 watt hr panel.
Take 12 panels 300 watts hr multiple that by 12 you get a ~3.8 kW system. Hence the small system.
Same for the mid and larger systems.
Yes, I understand the location of your panel position and sun exposure etc.. Let's not get too technical on that as well.
Sorry if I am coming across negatively. I been doing a lot of researching. Lots of decision to make.
Akikiki
A'-Lo-HA ! y'all
Let me clarify this statement having just got my first true up bill a few months ago and watching a $900 kWh credit get wiped to $0 with no payout (I am SCE, but I think all the CA utilities work the same minus the small co-ops/CCA)
You have to generate more KWH than you used in the year. Not kWh credits. So if I generated 10,000kWh for the year, but say I used 12,000kWh I am not eligible for any $$ back because I am not a net generator. I still had $900 in kWh credits at true up due to net metering and using most of my energy at night rates to charge the car when the solar was mostly dumping to the grid at the peak rates during the day.
So I paid about $20 to $25/month in NBCs (non bypassable charges) had $900 in credit at the end of the year, and that credit was wiped to zero. Seemed a bit like a kick in the gut, honestly.
I could have turned my system off for 2 months and burned down that credit, and I might consider it next year if my credits get that high again. As it is, we added a hot tub which will burn more energy.
So I feel like you can oversize your system in CA with the current rules if $$ is the only factor (not being greener, etc).
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