A friend was looking into solar with a Tesla wall (battery). I looked at
her APS bill - it was $120/month. They were seriously considering
spending $25K to cut down on the peak demand charge. The most they would
save was $20/month. That's an ROI that would never be achieved.
I have solar. APS invited me to buy a battery and they would pay me
$1250 if I let them manage it. The battery was quoted at $15K. Yeah, no.
So let's say I use the battery to keep my 4pm-7pm APS draw minimized,
what is my ROI? Looking at my past bills, my peak demand charge ranges
from $5 to $121 per month. Let's average that out to $65/month. So $15K
to save $65/month gives me an ROI of 230 months. It will be less due to
APS price increases, but that's still 15-20 years out, and by then the
battery would need to be replaced, nullifying any notion of an ROI.
Regards,
George Toft
On 11/26/2024 3:31 PM, Keith Smith via PLUG-discuss wrote:
Hi,
I have been curious about solar for sometime.
I am looking at my electric bill and I use less than 600k watts a
month for 1/2 the year.
My math does not seem to work out.
1) Convert 600000 watts at 120 volts * .1 = 60,000 watts at 12 volts.
2) 60,000 watts divided by 30 = 2000 watts at 12 volts per day.
3) If I can harvest solar for 4 hours a day that is 2000/4 = 500 watts
at 12 volts.
That means I only need 500 watts of solar. This does not take into
consideration loss of power in the system.
If the system losses 30% then I need around 715 watts of solar panels
to meet my needs.
I was expecting a lot more.
Any help is much appreciated!!
Keith
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