svetz
Works in theory! Practice? That's something else
Sunday morning with a cup of coffee and like many of you thinking about my bills. The power bill specifically and wondering what the price point per kWh needs to be to consider going off-grid. Let's tempt the calculator gods....
The electricity portion of my monthly power bill says the rate is $.0638/kWh.
But, the actual cost from everything else on the bill divided by the usage puts me at ~$0.15/kWh currently.
To keep the math simple, let's assume I use 50 kWh/d on average year-round and have an insolation of 5.
Over the next 20 years at 50 kWh/d, the sum of the utility bills will be $83,594 at 3% inflation or $74,731 at 2% inflation, or $66,991 at 1% inflation.
With an insolation of 5, to get 50 kWh/d I'd want a 10kW array, assuming a DIY cost of $1/W, that's $10,000. Leaving ~$64,731 for the battery at 2% inflation.
At a max of 50 kWh/d 2 days of autonomy is 100 kWh of energy storage.
So, assuming all that to be true, once battery prices fall below $64,731/100 kWh = $647/kWh the system would break even in 20 years at 2% inflation. At $323/kWh, the system would pay itself back in 10 years.
The Chins on Amazon is under $300/kWh, so are we there? Should DIYers start going off-grid?
What do you think?
Update: Thread recap in post: #190
Update: Example spreadsheet at
https://docs.google.com/spreadsheets/d/14AMvgJr2mxrx2NPxqzGxOkh3kuu4hjsc4KaJWOOP72o
The electricity portion of my monthly power bill says the rate is $.0638/kWh.
But, the actual cost from everything else on the bill divided by the usage puts me at ~$0.15/kWh currently.
To keep the math simple, let's assume I use 50 kWh/d on average year-round and have an insolation of 5.
Over the next 20 years at 50 kWh/d, the sum of the utility bills will be $83,594 at 3% inflation or $74,731 at 2% inflation, or $66,991 at 1% inflation.
With an insolation of 5, to get 50 kWh/d I'd want a 10kW array, assuming a DIY cost of $1/W, that's $10,000. Leaving ~$64,731 for the battery at 2% inflation.
At a max of 50 kWh/d 2 days of autonomy is 100 kWh of energy storage.
So, assuming all that to be true, once battery prices fall below $64,731/100 kWh = $647/kWh the system would break even in 20 years at 2% inflation. At $323/kWh, the system would pay itself back in 10 years.
The Chins on Amazon is under $300/kWh, so are we there? Should DIYers start going off-grid?
The advert for the Chins claims 2,000 cycles. 20 years of cycling is 7,300 cycles. Battleborn says 3k to 5k cycles. We know it has to do with the depth of discharge as shown to the right. Let's say the chart is correct. If we had 3d autonomy (150 kWh), the average usage would be 33% DoD which should get us to 8,000 cycles or >20 years. So $64,731 / 150 kWh = $431 kWh for a 20 year payback at 2% inflation, or $215/kWh for a 10 year payback. If you don't care about payback it seems like we might be there, the Chins has a payback under 14 years at 2% inflation. |
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Side note: If you have a good net-metering agreement, you'll probably never want to go off-grid....just increase the size of your PV to zero-out the bill...
What do you think?
Update: Thread recap in post: #190
Update: Example spreadsheet at
https://docs.google.com/spreadsheets/d/14AMvgJr2mxrx2NPxqzGxOkh3kuu4hjsc4KaJWOOP72o
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