At that rate of consumption, I assume you do not have an EV. Whether now or sometime in the future, you will be looking at getting one.
Consider roughly adding 4000 Kwh to annual consumption for approx 12000 miles in EV.
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Is my solar panel system too big?
- Thread starter Carbonfiber
- Start date
At that rate of consumption, I assume you do not have an EV. Whether now or sometime in the future, you will be looking at getting one.
Consider roughly adding 4000 Kwh to annual consumption for approx 12000 miles in EV.
i do have an EV, but I charge at work. The 6800 kwh was based on my past 12 months during the pandemic and with wife working from home since March. Energy usage was definitely higher than 2019.
if my annual usage was 6800 kwh and my solar panel system should generate 9600 kwh, shouldn’t I be coming out on top at the end of the year (besides the by passable charges)?
How is your power metered? Do you Time Of Use rates? Do you have full net metering?
Your system may be a bit too big but it is already installed, so try to make best use of it. For example you could use space heaters rather than central gas and consider heat pump when you upgrade hvac. Can also consider heat pump water heater if you can install those somewhere where the noise is not a problem.
After reading these comments, I am even more confuse!
As a new person investing in to solar panels for my home, I would think this system should cover all my energy usage for the year base on my past 12 months of energy usage. According to Tesla, this system should generate more than enough, but yet I still have to pay for electricity?
My system is oversized, shouldn't this make up for my energy usage and some?
Even if I downsize to the 4.08 kw system, I would save about $4k and the system would generate just enough to cover my usage. It’s probably to late now to do it, but I am just trying to educate myself and learn more about solar panels.
As a new person investing in to solar panels for my home, I would think this system should cover all my energy usage for the year base on my past 12 months of energy usage. According to Tesla, this system should generate more than enough, but yet I still have to pay for electricity?
My system is oversized, shouldn't this make up for my energy usage and some?
Even if I downsize to the 4.08 kw system, I would save about $4k and the system would generate just enough to cover my usage. It’s probably to late now to do it, but I am just trying to educate myself and learn more about solar panels.
It is not as simple as that because net metering is using $ amount at the time of generation and usage instead of kWh.
For example, using your numbers, averaging in a day, you generate 26 kWh and you used 18 kWh. Outside of non-bypassable charges, are you ahead that day? It depends on when you use the energy.
Scenario 1: 80% of usage outside of 4pm to 9pm during Summer
Generation = 26 * $0.27 = -$7.02
Usage = (80% * 18 * $0.27) + (20% * 18 * $0.43) = $5.44
In this case, you are ahead = 5.44 - 6.75 = -$1.31
Scenario 2: 30% of usage outside of 4pm to 9pm during Summer
Generation = -$7.02 (same)
Usage = (30% * 18 * $0.27) + (70% * 18 * $0.43) = $6.88
In this case, you are still ahead but barely = 6.88 - 7.02 = -$0.14
If you want to see the lowest bill possible, try to keep you 4pm-9pm usage under 70%. Definitely do not charge your car during that time if you can help it. Now you are thinking, it is really easy to keep evening usage under 70% of total usage. Yeah, because you oversized your system.
What happened if you sized it at exactly18kWh generation per day?
Scenario 1: 80% of usage outside of 4pm to 9pm during Summer
Generation = 18 * $0.27 = -$4.86
Usage = $5.44
In this case, you are behind = 5.44 -4.86 = $0.58
So even if you could keep your evening usage under 20%, you will still end up with a monthly bill of $17 + non-bypassable about $16 = $33.
Need, thanks for that explanation. In scenario 1, should the credit be $7.02 and not $6.75?
1. You are not going to be able to stay on a tiered system, SCE will move you to a time of use system 1-2 months after PTO
2. On TOU plans, WHEN you use and generate electricity matters, not just how much you use.
3. Peak time on TOU plans varies on plan, but is in general from 4-9pm or 5-8 pm with various differences in tarrifs.
The above means that, most of your PV will be generated during OFF PEAK rates, which credit you at a lower rate than you will be pulling from the grid during ON PEAK rates when you get switched to the time of use plan (mandatory for your PTO).
That means you NEED to generate more energy (solar) during the off peak time to offset the on peak usage. THAT means that, if you had bought the small system you would not be generating enough energy. You likely have the exact right size you need, as long as your energy profile doesnt change much. You have to overproduce on an Time of Use plan with solar, to offset the higher peak charges.
TL ; DR, no, your system is not too big, its likely the correct size to offset your current usage and have a near zero YEARLY bill. You will over produce during spring and summer like everyone with solar, and likely have to pull that banked energy back during fall and winter, like all PV owners. You need the size you got to get as close to zero as you likely want to.
EDIT: I think I was posting the same time as @Need.
Yes sorry, I thought I changed everywhere! Originally I used 25 kWh as daily generation so it came out at $6.75. Then I upped it to 26 kWh and thought I had modified all the equation but I guess I missed one! Good eyes!
BTW, just wanted to say, very nice, easy to follow explanation. Thanks for sharing.
Electrph
Member
@jjrandorin seems you are on sce ..
not sure if simple short answer to this but if i anticipate using zero from grid (based on my pre-PTO extensive off grid "testing" i am using zero from grid) if this continues thru summer would the tou 5-9 because of credits etc be much better vs the tou-D prime ? .. looking for lowest monthly non bypassable charges ..again assuming i use zero from grid each month
sorry for derailing thread a bit
not sure if simple short answer to this but if i anticipate using zero from grid (based on my pre-PTO extensive off grid "testing" i am using zero from grid) if this continues thru summer would the tou 5-9 because of credits etc be much better vs the tou-D prime ? .. looking for lowest monthly non bypassable charges ..again assuming i use zero from grid each month
sorry for derailing thread a bit
Yeah I am on SCE but dont have the answer to that question.... I have never sat down and attempted to calculate stuff out for myself because I am grandfathered in on NEM 1, and because of when I signed up for solar (2015) am also still on a regular ole tiered plan, not TOU.
The tiered plan, which just charges you for what you use, not caring about when you use it, works really well if you can keep your monthly usage in tier 1. In my specific case, I am a net producer generate more than I use) from Basically mid feb through late october. My yearly true up is in march, and I usually have close to zero true up charge.
I may be forced onto some TOU plan or other at some point in the future, but as long as I dont add any more solar I have another 14 years grandfathered on NEM1, provided some executive decision or other doesnt attempt to break those contracts.
Electrph
Member
sce actually still lists tiered plan as one of my options .. i assume that will not be avail once i have pto / on nem
Sorry for the derail for the OP (its somewhat related though, since it relates to SCE, which OP has) but yeah its my understanding that for the california utilities, PTO after a certain date requires being on a TOU plan. They dont dictate which TOU plan, but that you have to be on one of them.
Every time I have looked to see if I should switch (because I have an option, and I have powerwalls), because of my tiered rate having no real NBCs, it works out better for me to keep it. If I switch off of it, they will never let me get it back. I know SCE thinks the tiered rate is better for me as well, because 3 times over the past 2 years they have sent me emails like:
"We have randomly selected your account to move to a TOU rate, if you do nothing this will take effect on XX/XX/XXXX, you are a part of a pilot program that.....XXXX. If you would like to opt out of this pilot, contact us here".
I always rush to contact them and tell them "no, not interested, is this mandatory" and they tell me, no, not for you, we are just trying to move people to TOU rates and you were randomly selected as an account that could move, even though you dont have to". I sent letters in writing, emails, phone calls, telling them "I dont want this". I know they want to "helpfully" move me to a TOU rate that, by their own calculations, will cost me almost $1000 more a year than I pay now.
Thats how I know tiered is better for me.. they keep trying to get me off of it. I share others disdain for our CA utilities.. heh. Its one reason I got powerwalls, so I use as little power as possible from the utility. Its a personal thing.
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Just replace $0.27 and $0.43 with the ev2-a rate. That's PG&E right? OMG, just looking up that rate on the internet and it looks horrible for solar panel folks... $0.17 at peak solar generation period and $0.38 to $0.49 from 3pm to 12am. You only want to have that rate plan if you DO NOT have solar panel but you have an EV that needs charging. It looks similar to SCE's TOU-D-Prime rate.
The Prime rate is great for people with EV but no Solar. During the day when you need A/C, you get the super low rate. So you do all the heavy electric activities during the day before 3pm (running the pool pump, washing clothes, dish washer, A/C, watch daytime soap opera on you plasma TV LOL). And you charge your car after midnight or in the morning provided it finished before 3pm.
Yep, plan is terrible but am forced to be on. And makes it worse in winter when cannot charge batteries so for heat would have to maybe run heat pumps during the 4 to 12 super expensive time. Yep to pge.
brucet999
Active Member
Are Tesla panels that crappy? Panasonic HIT and SunPower/Maxeon guarantee more than 90% productivity at 25 years.
I think SCE will follow PGE closely. I am still grandfathered on SCE TOU-D-A plan which is amazing for me, but it is going away soon. When it does, I will have a $70 per month bill instead of just $17 even though I generate slightly more than I used. As more and more people get solar, they are just going to keep lower and lower the day time rate. In 10 years, day time rate is going to be like $0.10 per kWh and evening rate would be $0.65 and there is nothing we could do. It is still okay for me because my system will pay itself off in another 3 years.
