Sure, my bad, used using caps in my subject lines. Old habit. Fixing now.Please, no yelling....Use of capitals indicates shouting....and we don't like that here.
Do you mind if I change that? I think you can change that yourself, but just in case...
I've been trying to justify solar panels and am having a hard time making the numbers work. Looked at them both with and without a BEV; same calculation for me. Solar cost seems to be in the $3/W range installed, including panels and inverter(s). (Self install is possible to reduce costs further.) Here in the Northeast, you can plan for about 5 hours a day for output. At this time i pay under $0.14 per KWH from the power company. Ascetically, I would install a 6KW array for a cost of about $18K. So, for me I would reduce energy consumption by (5 x 6KW x 30 days) about 900KW / month; about $125. It would take a long time to recover the $18K initial investment (about 12 years if everything goes right). Yes, I would have an asset at the end, but they would be old solar panels. Larger arrays just make for larger costs and larger savings, but the relative cost of the Solar power remains the same. There are, at this time, some tax incentive to reduce the installation costs, but reducing the payback period from 12 to, say, 8 years just doesn't work for me. The Green aspect is beyond calculation and, for some, may be enough.I have been researching a lot about Solar PV (rooftop) and actually reviewed some 15 or so offers from many suppliers. I have locked in on one company and expect to install a 15kw system over next few months. Idea is to be Net Zero and I just revised the sizing to include an EV. I used the i4 as my EV and assumed about 10-12k miles/yr at about 36kwh/100 miles. I think that gave me about 330kwh/month to recharge the car at home, which is where I expect 90% of the time it will be charged.
I've got two nearby neighbors that have Teslas (one actually has 3!) and they also have Solar Roofs, so I assume they are doing very similar to what I am planning.
Has anyone else actually done this exercise and if so how did you estimate and calculate the amount of Solar PV you would need?
I added solar and battery a few years ago because here on California we were having black/brown outside to fires.I've been trying to justify solar panels and am having a hard time making the numbers work. Looked at them both with and without a BEV; same calculation for me. Solar cost seems to be in the $3/W range installed, including panels and inverter(s). (Self install is possible to reduce costs further.) Here in the Northeast, you can plan for about 5 hours a day for output. At this time i pay under $0.14 per KWH from the power company. Ascetically, I would install a 6KW array for a cost of about $18K. So, for me I would reduce energy consumption by (5 x 6KW x 30 days) about 900KW / month; about $125. It would take a long time to recover the $18K initial investment (about 12 years if everything goes right). Yes, I would have an asset at the end, but they would be old solar panels. Larger arrays just make for larger costs and larger savings, but the relative cost of the Solar power remains the same. There are, at this time, some tax incentive to reduce the installation costs, but reducing the payback period from 12 to, say, 8 years just doesn't work for me. The Green aspect is beyond calculation and, for some, may be enough.
Business school taught me the payback period was passe', but that was in a period of high interest rates. Time Value of money was preferred, but I'm too out of practice to run those numbers. Still, at my age, anything over 7 years just seems to long for me. At today's exchange rate ($1.09 / Euro), 2 Euro per watt is a good price, about on par with US lower cost installs. If you installed yourself, I'm not surprised you saved 30% from professionally installed systems. I think the real benefit is in going green and I can't put a price on that.What payback period are you aiming for?
3$ for 1wp seems to be quite expensive.
I installed Sunpower 400wp panels and solar edge inverter for less then 2€ for 1wp.
Our power grid has been quite reliable for me in my ten years on this property. Were it not, the most cost effective solution for me would be a back up generator (I've got a 500 gal propane tank for cooking and backup heating). About 6KW is also what I looked at and your net $15K cost is not too far off what I'm being quoted today Finance, cash, opportunity cost, whatever, it's still capital cost. So, $15K+ in capital cost saves you about $125/month for electric. Hopefilly the system is maintenance free. I'm a little green, but not Kermit. Gee, that's often why we buy BEV's. For me, I just couldn't objectively justify a solar system at today's prices based simply on $ saved in electricity.I added solar and battery a few years ago because here on California we were having black/brown outside to fires.
A couple of times it was long enough to ruin food. So my 6kw system with a 15kwh battery was $26k and I got a 30% tax credit bringing the system cost down to about $15.5k
I didn't calculate the ROI since it didn't matter, but it's about 10 years. I financed the system at 2% and 10 years.
I was already getting an EV rate. I run off the battery most days during peak and sell energy back at the highest rate.
I plan to take advantage of the free charging for the i4 as much as possible.
Waiting on my Tanzanite M50!
No real maintenance. I rinse the panels to keep dust and dirt off.Hopefilly the system is maintenance free. I'm a little green, but not Kermit. Gee, that's often why we buy BEV's. For me, I just couldn't objectively justify a solar system at today's prices based simply on $ saved in electricity.
Strongly agree on the reduced long term cost of BEV vs. ICE. For solar panels, the results certainly differ on the environment in which they're installed. Arizona (and South Florida) is going to get more sun than a wooded lot in Pennsylvania and electric rates also vary. A quick check shows South Florida around $0.11/kWh total. Solar use offsets that directly but the price for selling back to the grid is probably their generation cost, not including distribution, so, less. The clearly lower payment to the Utility is offset by the payments (or lost opportunity costs) on the capital invested. It would be a nice thing to show a low utility bill to a potential buyer, but you did prepay that bill with your invested capital.OK, so I see a number of you have done some homework on this. I put together a spreadsheet with some (12) or so offers from multiple providers and then of course I used "realistic" long term costs which none of the installers tell you about. Such as in Florida, if you exceed 10kw you need to provide a $1.0m Liability Policy. In my case it is quite cheap via USAA, I had $500k and increasing to $1.0m only cost me about $36/year. Others have reported several $100's per year. Then your home value has to be increased in your home insurance policy so that goes up as well but only on a prorata basis for the added value, another $347/yr. They didn't care if it was Solar or a Garage, it was just additional value. Then you have to figure some amount for maintenance and repair. Installers claim maintenance free but we all know the reality of that. Kid hits a panel with a rock, baseball, etc... who is paying for that? They will have to be cleaned periodically (annually?). So I figured about $200/yr for that. In my case I was looking at a 12kw system so about $36k before applying the 26% tax incentive. My payback or ROI was coming in right around 10 years so not that impressive, but as soon as I added in an EV, I had to increase my system to 15kw which brought my cost to $39.3k, about $2.65/w, but now my ROI is about 6.4 years. Our electricity rates have gone up after recent approval and I fully expect they will continue to increase further, you have to make some basic assumptions. And I assumed I needed about 300kw/month to charge the i4 driving 10k/year. I offset my estimate to purchase gas at some $5.0/gal, and when will that go back down? My end result is to be Net Zero so I get full advantage that our utility has to buy back my excess at same rate as they charge (something that was recently changed by law but was grandfathered for 20 years). I already added additional attic insulation and LED lights throughout, and new A/C and Pool Pump, and Hybrid Water Heater which is a major plus. My consumption is about 1,600kwh/month in a 2700sqft home in South Florida. I'll try to share my spreadsheet if I figure how to get it uploaded. I feel that 6-7 years is a reasonable return and of course you still have residual and resale value, but that is very much market driven when it comes time to sell. I really think EVs will be the car of the future and home buyers will appreciate having a solar system already there so they don't have to go through the hassles of approvals, etc... And when you show your electric bill is some $10-$12/month! And no Gasoline. Real quick my calculations show about a $175/month savings just by switching to an EV vs gas.
I hear you. When power goes out, I lose my well pump and only have a couple dozen gallons of water in my pressure tank. An extended outage could also cost me some food. Good thing it's rare here. To offset with solar,I would need not just the solar panels but a battery (thinking "Solar Wall") backup, increasing the system cost. (Funny how power can go out at night or in storms.) Not as green, but a propane powered generator is a more cost effective solution for me. Haven't even bothered, as I'm fortunate to live in an area with reliable electricity.Pure savings wasn't the justification. Having power in a blackout was my justification. It has come in handy a few times.
We had someone run into a pole and power for the neighborhood was out for about 16 hours. My neighbor and I had power and lights.
I've been going on about the cost effectiveness of solar without directly addressing your question - sorry.I used the i4 as my EV and assumed about 10-12k miles/yr at about 36kwh/100 miles. I think that gave me about 330kwh/month to recharge the car at home, which is where I expect 90% of the time it will be charged.
Has anyone else actually done this exercise and if so how did you estimate and calculate the amount of Solar PV you would need?
Our Electricity rate went from around $0.11 to almost $0.15 this last month, they got a 20% increase or something like that. With Net Metering it is a kwh for a kwh, averaged out over the year. There is no peak time, etc... If I consume 1,600kwh in a month, and produce 1,600kwh that same month, I pay zero for my energy, only a small monthly admin fee of like $12.0. They actually average it out over a year with Net Zero as the design basis. If you send back more than 15% of your actual consumption, they can disconnect you. Any positive is rolled over to next year and of course any negative you pay at going rate. I think all of that is about to change, as they will now be able to recover their fixed costs as you mention, but it is grandfathered for anyone that has installed or will install until next year, then it starts to get reduced. Those grandfathered will get Net Zero for 20 years. Basically we are using the grid as one big battery, free of charge so to speak. Adding a battery would destroy the ROI. So yes, other than the "Green" badge, going solar would not be cost effective without the tax incentives, etc...Strongly agree on the reduced long term cost of BEV vs. ICE. For solar panels, the results certainly differ on the environment in which they're installed. Arizona (and South Florida) is going to get more sun than a wooded lot in Pennsylvania and electric rates also vary. A quick check shows South Florida around $0.11/kWh total. Solar use offsets that directly but the price for selling back to the grid is probably their generation cost, not including distribution, so, less. The clearly lower payment to the Utility is offset by the payments (or lost opportunity costs) on the capital invested. It would be a nice thing to show a low utility bill to a potential buyer, but you did prepay that bill with your invested capital.
We designed our home with a lot of energy efficiencies, including passive solar, about ten years ago. There were some increased costs, but we liked the look and the efficiencies. Utilities are low. I did skip the Ground Source heat pump, as installation costs exceeded any real savings in my lifetime. I have no doubt that BEV 's and solar are a green solution. I just can't make the active solar work as a cost effective solution (in my location) to my energy needs. YMMV.
Todd, adding battery would be like $10-$13k and under current Zero Net Metering rules would make no sense unless I was concerned about blackouts. We really only see those when a bad hurricane strikes the area, which happens but is quite infrequent. If the rules change and they start to apply time of use, etc... maybe a battery would make sense, but easy enough to add later.I've been going on about the cost effectiveness of solar without directly addressing your question - sorry.
I think your estimates are correct for the power required and kind of provide their own answer. To zero out the charging cost, you'd need to generate 330kwh per month. Figure 5 hours a day of solar energy, depending on your location. Looks like an additional 2-3KW in the array is sufficient to "zero out" the car (plus whatever you need for the residence). Your solution could be to simply "wash" the power using the grid as the sink. Battery storage is also possible and can be used to take advantage of time/demand related electricity rates, but adds to the cost.
xT, that same 15kw in South Florida would generator about 20,000kwh in a year, 20MWh. It will power my home plus one EV based on my estimate. My cost is $29,150 so just under $2.00/w after 26% tax incentive, which is being reduced in the future. It was 30% last year. I seriously think there is a conspiracy to make fossil fuel so expensive that Solar becomes much more attractive and they pull away the incentives. Basically force people to change, one way or the other.I installed a 15 kW system two years ago and paid 15kUSD after 5k subsidy (12kW inverter). Price was a bargain and has increased since.
ROI 8 years then - with todays electricity prices shorter.
Here in Stockholm is spring and March was a good month:
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Last years production was above 13,5 MWh. I live in a northern location. The closer to the equator you get, the more equally spread are the sun hours during the year, and you getter better production figures in total.
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Buying a battery is not profitable yet. Especially when you can sell surplus to the grid at a high unit price.
Yesterday, an electrician installed a Zappi v2 that with a hub and smartmeters (measure grid and solar production) can adapt charging your car according to your needs, ie only charge if there is a solar surplus or just charge at maximum level (up to 22kW) - always prioritizing the households consumption first and avoiding fuses to break.
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20MWh compensates for your higher investment.xT, that same 15kw in South Florida would generator about 20,000kwh in a year, 20MWh. It will power my home plus one EV based on my estimate. My cost is $29,150 so just under $2.00/w after 26% tax incentive, which is being reduced in the future. It was 30% last year. I seriously think there is a conspiracy to make fossil fuel so expensive that Solar becomes much more attractive and they pull away the incentives. Basically force people to change, one way or the other.
That looks really cool, very simple graphical representation. Even I can figure it out!20MWh compensates for your higher investment.
Here it is the taxes that usually rise the prices - lastly of course the uncertainty of oil supply. Don’t believe in conspiracy on market prices. Solar panels prices rise also.
Today is a miserable day when it comes to solar supply, but I like the graphics in the app where you can remotely control charging options (charging my bmw 225xe right now):
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