Hi all,
This is my first post on SolarPanelTalk. Just registered today. I'm an ex-mechanical engineer (20 years). Been teaching HS math for the last 14 years. Been interested in solar panels for about 10 years, had several quotes done, but never pulled the trigger. Had an idea a few months ago which I've been mulling over. Now it's summer, I'm getting more serious about it.
Here's the idea:
Here in California, we have tiered residential pricing. In Long Beach, where I live, the pricing from Southern California Edison is:
Tier Tier1 Tier2 Tier3 Tier4
Cents per kWh 13¢ 16¢ 27¢ 31¢
In a nutshell, the idea is to build a PV system just large enough to offset power usage that exceeds Tier 2 and is priced at Tier 3. Then, I buy cheap power from SCE in Tier 1 and 2, and I credit myself for the power from my small PV system at 27-31 cents per kWh Tier 3 and 4.
OK, I know it's not as simple as that, and I didn't expect it would be. I suspected that SCE would not re-imburse me at 27 cents. Rather, I suspected they would re-imburse at the lowest rate first, then at higher rates as a grid-tied system feeds more power into the grid, only re-imbursing at the highest rate as the point of zero net power usage is approached. So, I called SCE to ask about reimbursement rates and was completely brushed off. "We don't determine that. The CPUC determines that. It depends on your installation. Call this number for the California Solar Initiative. Solar is our competition. We are not answering any questions about solar, period. Go the frack away. Are you still asking questions? GO THE FRACK AWAY!" So I called the number they gave me for the CSI, and it referred me to the information on SCE's Website, which does not explain the reimbursement rate. Niiiice. Now, I am here.
Here's my very rough analysis, so far. My March 2013 bill from SCE was a typical bill for me:
Tier Tier1 Tier2 Tier3 Tier4 Tier5
Cents per kWh 13¢ 16¢ 29¢ 33¢ 36¢
My usage: Tier1 Tier2 Tier3 Tier4 Tier5
kWh 307 92 44 0 0
Yes, I know this is five tiers, but I think the pricing just recently changed to four tiers for residential usage. So, the four tiers given above are the current tiers, but since this bill was a March bill, it was still five tiers then. Using the March bill, the charges were $67.39 total, and the Tier 3 usage accounted for 9.9% of my power, but 17.6% of my bill. The total power usage for the month was 443 kWh, and I figure a 600W system could supply about 10% of that. That's just two or three panels, depending on the size. Basically, I just want to cap my rate at 16 cents per KWh. Actually, I might go a bit higher on the Watts in case I use more power in the future, or SCE's pricing structure changes. But, you get the idea.
The problem seems to be, how to get reimbursed at the higher rate. I was thinking, the only way to get reimbursed at the higher rate would be to do a non-grid-tied, battery type system, but that would mean wiring some parts of my house for the battery system and some parts to remain powered by SCE. Not very appealing for such a small system. On the other hand, I do have a freezer and a freezer/refrigerator in the garage (I home brew), which could provide a very predictable load for an off-grid system. The problem here is, I don't have any experience estimating the economics of a battery based system.
[Edit, July 2, 1:21 PM: OK. Done some reading on this site about battery systems. Now I know the off-grid, battery approach would make no economic sense. That leaves the grid-tied approach.]
Then, my son found a thread on this site containing comments by "Stomp" about a 7.5 kW system, that seems to achieve an equitable billing rate by using a smart meter and a TOU billing plan.
At this point, I'm looking at this two ways:
1) If Stomp's analysis was correct, a viable approach could be a grid-tied system, using a smart meter, and TOU billing.
2) If the only way to obtain the 27 cent per kWh offset is with an off-grid, battery type system, the approach looks less attractive because of the extra expense of the batteries.
I suppose a third way to look at it would be as a modified No. 1, by adding batteries; then, it's also a backup system in case of a power outage.
Well, any general feedback on the economics of the idea, any of these tacks, or a different tack, or a project they have tried like this, would be welcome.
This is my first post on SolarPanelTalk. Just registered today. I'm an ex-mechanical engineer (20 years). Been teaching HS math for the last 14 years. Been interested in solar panels for about 10 years, had several quotes done, but never pulled the trigger. Had an idea a few months ago which I've been mulling over. Now it's summer, I'm getting more serious about it.
Here's the idea:
Here in California, we have tiered residential pricing. In Long Beach, where I live, the pricing from Southern California Edison is:
Tier Tier1 Tier2 Tier3 Tier4
Cents per kWh 13¢ 16¢ 27¢ 31¢
In a nutshell, the idea is to build a PV system just large enough to offset power usage that exceeds Tier 2 and is priced at Tier 3. Then, I buy cheap power from SCE in Tier 1 and 2, and I credit myself for the power from my small PV system at 27-31 cents per kWh Tier 3 and 4.
OK, I know it's not as simple as that, and I didn't expect it would be. I suspected that SCE would not re-imburse me at 27 cents. Rather, I suspected they would re-imburse at the lowest rate first, then at higher rates as a grid-tied system feeds more power into the grid, only re-imbursing at the highest rate as the point of zero net power usage is approached. So, I called SCE to ask about reimbursement rates and was completely brushed off. "We don't determine that. The CPUC determines that. It depends on your installation. Call this number for the California Solar Initiative. Solar is our competition. We are not answering any questions about solar, period. Go the frack away. Are you still asking questions? GO THE FRACK AWAY!" So I called the number they gave me for the CSI, and it referred me to the information on SCE's Website, which does not explain the reimbursement rate. Niiiice. Now, I am here.
Here's my very rough analysis, so far. My March 2013 bill from SCE was a typical bill for me:
Tier Tier1 Tier2 Tier3 Tier4 Tier5
Cents per kWh 13¢ 16¢ 29¢ 33¢ 36¢
My usage: Tier1 Tier2 Tier3 Tier4 Tier5
kWh 307 92 44 0 0
Yes, I know this is five tiers, but I think the pricing just recently changed to four tiers for residential usage. So, the four tiers given above are the current tiers, but since this bill was a March bill, it was still five tiers then. Using the March bill, the charges were $67.39 total, and the Tier 3 usage accounted for 9.9% of my power, but 17.6% of my bill. The total power usage for the month was 443 kWh, and I figure a 600W system could supply about 10% of that. That's just two or three panels, depending on the size. Basically, I just want to cap my rate at 16 cents per KWh. Actually, I might go a bit higher on the Watts in case I use more power in the future, or SCE's pricing structure changes. But, you get the idea.
The problem seems to be, how to get reimbursed at the higher rate. I was thinking, the only way to get reimbursed at the higher rate would be to do a non-grid-tied, battery type system, but that would mean wiring some parts of my house for the battery system and some parts to remain powered by SCE. Not very appealing for such a small system. On the other hand, I do have a freezer and a freezer/refrigerator in the garage (I home brew), which could provide a very predictable load for an off-grid system. The problem here is, I don't have any experience estimating the economics of a battery based system.
[Edit, July 2, 1:21 PM: OK. Done some reading on this site about battery systems. Now I know the off-grid, battery approach would make no economic sense. That leaves the grid-tied approach.]
Then, my son found a thread on this site containing comments by "Stomp" about a 7.5 kW system, that seems to achieve an equitable billing rate by using a smart meter and a TOU billing plan.
At this point, I'm looking at this two ways:
1) If Stomp's analysis was correct, a viable approach could be a grid-tied system, using a smart meter, and TOU billing.
2) If the only way to obtain the 27 cent per kWh offset is with an off-grid, battery type system, the approach looks less attractive because of the extra expense of the batteries.
I suppose a third way to look at it would be as a modified No. 1, by adding batteries; then, it's also a backup system in case of a power outage.
Well, any general feedback on the economics of the idea, any of these tacks, or a different tack, or a project they have tried like this, would be welcome.
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