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Who has solar power at their home? Please chime in....
- Thread starter ozziegn
- Start date
We not only have net metering, but also time-of-use pricing. As I understand it in Northern California with PG&E, our solar panels pump out electricity to the grid during the day when rates are relatively high. In the evening we use electricity from the grid that is more expensive still. The Tesla charges after 11:00 pm at very low rates. Although our total consumption is greater than our production the cost of our consumption is less than the gain of production.
We installed a small 6-panel array at first to eliminate the "tier 4 pricing" before we leased a little Chevy Spark EV. Once we drank the KoolAid we knew a Tesla was in our future so we added 18 more panels. Our calculations are imprecise but suggest a 6-7 year payback. If I attempt to add the avoided price of gasoline for transportation this goes down (I think?)
We did this mostly for financial reasons - but driving up to the house with all those panels on our south facing entrance I feel so damned pius and green - that's a small immeasurable benefit too. Batteries to come? The grid is our battery until they monkey with the rates.
We installed a small 6-panel array at first to eliminate the "tier 4 pricing" before we leased a little Chevy Spark EV. Once we drank the KoolAid we knew a Tesla was in our future so we added 18 more panels. Our calculations are imprecise but suggest a 6-7 year payback. If I attempt to add the avoided price of gasoline for transportation this goes down (I think?)
We did this mostly for financial reasons - but driving up to the house with all those panels on our south facing entrance I feel so damned pius and green - that's a small immeasurable benefit too. Batteries to come? The grid is our battery until they monkey with the rates.
How'd you manage to get approval from Xcel for 300% of your annual production? Normally they limit you to a system that is only up to 125% of your previous annual usage. After several requests, we were only able to get approval for 141% (125% plus an annual kWh allowance for a new electric vehicle).
srs5694
Active Member
This may be counterproductive, at least on a broad societal scale; but whether it's beneficial to you personally depends on the contract details about how you pay for electricity and how (or if) your solar panels are connected to the grid.
Assuming your solar panels are grid-connected, they provide power to the grid (broadly defined, to include your house) no matter what you do. If you were to completely stop using electricity on a sunny day, then 100% of your production would go to your neighbors and reduce load on the local power station, compared to your not having solar panels. If you turn on every appliance in your home and charge your cars on a sunny day, then most or all of your production will go to that, thus reducing load on the local power station, compared to your not having solar panels. That is, your solar panels provide a benefit no matter what you do. Flipped around, if you charge your car when the sun is up, you'll be charging (partly or completely) from solar power, but that power will not be going to your neighbors, so the load on the local power station will increase, even though you've got solar panels on your house and the electricity they produce is going into your batteries.
In many areas, grid load rises throughout the day, peaking in the mid-to-late afternoon. At this time, utilities often bring their most expensive and most polluting power stations on-line. Because charging your car, even with a grid-connected solar array on your house, increases grid demand, this results in an increase in pollution from those most-polluting power stations.
Of course, there are a lot of caveats and exceptions to this rule, most of which are regional or site-specific:
- Is your house grid-connected? If not, you'd want to charge when your panels are producing the most electricity; the grid doesn't matter.
- What's the overall power production look like for your area? In particular, what types of peaker plants exist in your area, to provide that extra late-afternoon "kick" in production? A few areas in the US, such as parts of California, now have so much solar power installed that they over-produce around mid-day, and have to throw electricity away as a result, so charging at mid-day might be beneficial.
- What's the overall demand curve in your area, and on the day you're considering? This varies regionally, seasonally, and on a day-to-day basis.
- Do you have a battery system, like a Tesla Powerwall, to store solar power? If so, then your house's electricity demand is likely to be low throughout the day, and you should probably charge your car whenever you're producing the most power, although details will depend on your system.
- Are you on a flat-rate or time-of-use (ToU) billing system? This doesn't affect the environmental impacts of when you should charge, but it's typically designed to motivate electricity use to match the utility's costs, and indirectly the environmental impacts, so charging when rates are low is a decent proxy for when charging imposes the lowest environmental costs.
- What are the details of your solar power installation's grid connection? That is, are you on net metering, a feed-in tarriff, or something else? Is billing done monthly, or is there a time-of-day component? These will affect the economics of it, but likely not the environmental costs of charging.
Have a small 1kw system that I use to offset some of the charging of my M3 during the day. Bigger system didn't make sense as the highest bill was $88 last month. Beyond that Tesla's offer of $50 a month rental for a system can't be beat, then you could add one of their Powerwalls for nighttime use if needed.
Alto Nimbus
Member
Many smart people being very helpful on this forum. A couple of more thoughts about Solar in FL,
How much roof life is left can deter people from adding solar panels as a new FL roof can be expensive and added to a solar install can put the project out of reach or delay it years until the reroof is undertaken. Dorian was 60 miles from my house when it turned North. No one in FL can predict roof life beyond the start of hurricane season.
Adding solar and batteries, at least in my mind increased the value of my home. I hope it also makes the property more desirable if I ever decide to sell. In FL, solar and batteries, unlike most other home improvements can’t be used by the county tax appraiser to raise your property taxes.
I’ve seldom been the recipient of such tangible benefits from the tax code as the rebates on solar, batteries and the electric car.
dgpcolorado
high altitude member
My take on solar is somewhat different from the "green eyeshade" ROI calculations. I put in my first 700 watt array in 2008 as "phase 1" of a future electric car. The panels were not remotely cost-effective back then (35 year payback) but I budgeted it as part of the price of an electric car. In 2012, after driving an electric car for awhile, I knew what my actual electricity usage was so I added another 1470 watt array, putting my total at 2170 watts. As before, solar prices were much higher then than now so my new array wasn't cost-effective — I considered it part of the cost of my electric car. My view is that "people by less useful toys than solar panels, do they not?" It seems odd to me that people will calculate ROI on solar panels to the penny but then go out and buy a fancy new car, when buying a used car, or just keeping the old one, is far more cost-effective. Doesn't make sense. No, my solar arrays weren't cost-effective but I'd much rather have them than a hot tub or boat or some such thing. I like "driving on sunshine" and I seem to be something of an early adopter when it comes to doing that.
I ground mounted my panels because I didn't want to mess with my precious roof or string lines though an attic with blow-in fiberglass insulation (I hate working up in the attic). My pole-mounted panels were more expensive than roof mounted ones because of the extra hardware and racks needed. I did my own post hole and conduit trench digging (lots of rocks since I live on a glacial moraine) and did my own concrete work, but I let the local solar installer handle everything else. One advantage of my pole mounted arrays is that I can adjust the pitch of the panels with the seasons, from 15º in the months around the summer solstice to 55º around the winter solstice. I just adjusted my panels down to 35º yesterday. Besides improving solar production in winter, the steeper angle helps me with pulling the snow off — I use a window squeegee on a long painter's pole to do that after each snowfall.
My 2170 watt solar array provides all the electricity I need to run my house and fuel my car, although I do some opportunity charging at public charge stations when I can. My local electricity cooperative is very supportive of renewables and net metering because we, the member-owners of the co-op, influence the policy. My co-op even offers a solar rebate for up to 3 kW of panels and a $750 electric car rebate. When I first put in my panels the co-op had a "true-up" (to zero out any accumulated solar credits at the wholesale electricity rate) in June, a poor time for it. We net meter customers lobbied to have it changed to March. A few months later the co-op just got rid of the true-up entirely and now lets us carry the credits forward as long as we like, so long as we don't exceed 10,000 kWh. My current credit is about 1300 kWh, which is plenty to get me through the winter when solar production declines and my electricity usage increases. [No AC needed here in the mountains, of course. I use passive cooling in summer: windows open at night when it is cool outside and shut during the day when it is warm.] I haven't paid an electric bill, other than the basic $20/month service charge, since 2012.
My 2¢.
Solar array at summer solstice pitch of 15º:
Solar array before pulling off snow in winter:
I ground mounted my panels because I didn't want to mess with my precious roof or string lines though an attic with blow-in fiberglass insulation (I hate working up in the attic). My pole-mounted panels were more expensive than roof mounted ones because of the extra hardware and racks needed. I did my own post hole and conduit trench digging (lots of rocks since I live on a glacial moraine) and did my own concrete work, but I let the local solar installer handle everything else. One advantage of my pole mounted arrays is that I can adjust the pitch of the panels with the seasons, from 15º in the months around the summer solstice to 55º around the winter solstice. I just adjusted my panels down to 35º yesterday. Besides improving solar production in winter, the steeper angle helps me with pulling the snow off — I use a window squeegee on a long painter's pole to do that after each snowfall.
My 2170 watt solar array provides all the electricity I need to run my house and fuel my car, although I do some opportunity charging at public charge stations when I can. My local electricity cooperative is very supportive of renewables and net metering because we, the member-owners of the co-op, influence the policy. My co-op even offers a solar rebate for up to 3 kW of panels and a $750 electric car rebate. When I first put in my panels the co-op had a "true-up" (to zero out any accumulated solar credits at the wholesale electricity rate) in June, a poor time for it. We net meter customers lobbied to have it changed to March. A few months later the co-op just got rid of the true-up entirely and now lets us carry the credits forward as long as we like, so long as we don't exceed 10,000 kWh. My current credit is about 1300 kWh, which is plenty to get me through the winter when solar production declines and my electricity usage increases. [No AC needed here in the mountains, of course. I use passive cooling in summer: windows open at night when it is cool outside and shut during the day when it is warm.] I haven't paid an electric bill, other than the basic $20/month service charge, since 2012.
My 2¢.
Solar array at summer solstice pitch of 15º:
Solar array before pulling off snow in winter:
Code:
Electricity production from my solar arrays:
2008 232 kWh
2009 1165 kWh
2010 1132 kWh
2011 1203 kWh
2012 1409 kWh
2013 3327 kWh
2014 3217 kWh
2015 3159 kWh
2016 3227 kWh
2017 3277 kWh
2018 3306 kWh
2019 2143 kWh
Total = 26,797 kWh
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The installers quoted us an 80% system when they installed it. They took care of the deal with Excel, and I never heard of any kind of 'approval' needed. We didn't have the roof real estate for 100% coverage. Which based on our previous average usage - that was correct.
Excel (assumedly) loves the fact that they are buying up our power for grid usage, and they basically told us we aren't getting that good of a deal using solar power (talking us down from some magical cloud perhaps) - but then again, that's only for 10 yrs. (after that they get it for free - even better for them right?) Boulder wanted to get most people producing on the grid providing for the county once upon a time. I think they were trying to get Boulder running it's own power company, away from Excel - but I may be off there.
I could care less actually, to me it's all about moving in the right direction with renewable energy. And I do think buying is the right choice. Going off grid would be even better. My other thought were the panels you see outside of town that they sell to people, or offer to people to use solar power. Sounds good on the surface, but when you think about that - how do I know they aren't selling power created from 'my solar panels' to more then just me? - in other words, they can just keep selling the same panel outputs over and over making a killing on that service right? Seems like having your own, on your own roof is the way to go. (mojonovich is my other login)
In San Diego we have net metering and time of use plans available. We charge our teslas at super off peak midnight to 6am and are on a TOU plan that only charges us $0.09/kWh during those hours.
Peak rates in summer 4p-9p are over 4x that cost and winter peak and off peak times are about 3x the cost. We realized literally ** 87% ** of our electricity use is during those super off peak times. Most of that's the cars but some is AC and pool pumps. And with net metering since our solar output is mostly during off peak and peak hours we found that a solar system that covers only about 50% of our use would actually nearly zero out our bill.
We're planning to try to fill our west facing roof with panels to produce some during the peak hours and planning on spending a bit more for 360w panelsto really max it out.
Unfortunately Tesla would only do a 13 or 26 panel system and our sweet spot seems to be around 15-18 panels so we probably won't end up going with them although i'd love to. They also weren't flexible with higher efficiency panel options.
We got another quote at around $1.88 to $1.95/W (after 30% fed) pretty close to Tesla's price.
Planning a few more panels anyway to crank the AC a little more liberally (happy wife) and be ready for rate increases, panel degradation, etc.
Not directly driving on sunshine but that nightime energy is cheap because they have abundant power churning out and basically need to get rid of it...ive heard CA power companies even pay AZ to take some excess power sometimes (???). We're also producing for them when everyone's cranking their AC and whatnot and energy is expensive...flattening the demand curve as they say.
Peak rates in summer 4p-9p are over 4x that cost and winter peak and off peak times are about 3x the cost. We realized literally ** 87% ** of our electricity use is during those super off peak times. Most of that's the cars but some is AC and pool pumps. And with net metering since our solar output is mostly during off peak and peak hours we found that a solar system that covers only about 50% of our use would actually nearly zero out our bill.
We're planning to try to fill our west facing roof with panels to produce some during the peak hours and planning on spending a bit more for 360w panelsto really max it out.
Unfortunately Tesla would only do a 13 or 26 panel system and our sweet spot seems to be around 15-18 panels so we probably won't end up going with them although i'd love to. They also weren't flexible with higher efficiency panel options.
We got another quote at around $1.88 to $1.95/W (after 30% fed) pretty close to Tesla's price.
Planning a few more panels anyway to crank the AC a little more liberally (happy wife) and be ready for rate increases, panel degradation, etc.
Not directly driving on sunshine but that nightime energy is cheap because they have abundant power churning out and basically need to get rid of it...ive heard CA power companies even pay AZ to take some excess power sometimes (???). We're also producing for them when everyone's cranking their AC and whatnot and energy is expensive...flattening the demand curve as they say.
Thanks to Obama, I got a great addition to phase 1 Solyandra panels, with two pallets of Phase II-2 solyandra panels. Unfortunately these self ballasting, glass tube based thin film systems, that positioned north south and retain equal amounts of light from morning to sunset, without repositioning and work from summer to winter equally converting sunlight to electricity, were discontinued. The Chinese have the wisdom to subsidize their solar industry, as Obama did that facilitated the production of the phase II solyandras, but without continued subsidies this company went bankrupt. The rare earth materials and costs of manufacturing exceeded the cost of flat panels.
That said they are great and produce and have produced for the last 10 years, when i installed phase 1 and since 2012 when I installed phase II to create a combined array of 7500 watts, that actually rarely produced more than 6200 watts. I have trees and dust in New Mexico that knocks down the efficiency, but what is left is just fine and during the spring and fall I get a check from the power company for my grid-tie system. Now I use it to cool the house in the summer and charge the Tesla during the day and my electric bill has not changed from last year. The trick is to charge when the solar array is peaking, but the collective or aggregate of every day's power generation is metered and measured against what I consume. I charge every time the Tesla returns to the garage when the sun is out or it isn't cloudy. The car is named Solar*Car ! Cause it is!
Need to put SOLYANDRA type panels back into production ! Especially with a highly reflective PVC white roof.
That said they are great and produce and have produced for the last 10 years, when i installed phase 1 and since 2012 when I installed phase II to create a combined array of 7500 watts, that actually rarely produced more than 6200 watts. I have trees and dust in New Mexico that knocks down the efficiency, but what is left is just fine and during the spring and fall I get a check from the power company for my grid-tie system. Now I use it to cool the house in the summer and charge the Tesla during the day and my electric bill has not changed from last year. The trick is to charge when the solar array is peaking, but the collective or aggregate of every day's power generation is metered and measured against what I consume. I charge every time the Tesla returns to the garage when the sun is out or it isn't cloudy. The car is named Solar*Car ! Cause it is!
I don’t know if ur local power company XCel has strict rules about that or not, but here in SoCal, Ladwp has the same restriction. But I was able to go 200% size than their limitation. I convinced them that Im going to add 2 more electric cars to my house. Gave them the kW calculation for one car. They did their math and came up to me with a number and asked me to show the confirmation for ordering new cars.
yes I showed them that I have 2 model 3 reservations at that time then they approved my solar system. After that, I cancelled my m3 reservations :|
nwdiver
Well-Known Member
Xcel has a similar method. Not sure if a reservation would work but you can add ~3MWh/yr to your consumption if you've recently purchased an EV...
I don't follow your numbers. To whom is or was the $280 a month payment and why is your bill $-156? Others seem to understand, and I see similar postings, but better if you can break it down.
No, the ITC doesn't "expire" on 1 January, it just drops from 30% to 26%.
Details:
Solar Investment Tax Credit (ITC) | SEIA
Our situation has been optimal, but we're in Texas and have deregulated power with 100% buy back--the grid is our battery. Our pay back time was 1 year and 4 months; from that point forward we save about $6k per year which certainly helps pay for our Tesla addiction
We installed an 8 kW system, but should have gone larger as we left some south-facing roof uncovered. Dumb move. If you have a great roof orientation, USE IT.
Doing so "future proofs" your home as eventually, nearly all cars will be EV's, so why not be ready for that eventuality?
Also, while you're there, in all cases there will be electrical work being done. Be sure to specify, "Two NEMA 14-50 outlets will be installed in the garage for convenient Tesla charging." (Or three if you have a 3-car garage, etc.)
It's the time to do it, not after-the-fact.
You need another Tesla or three--what a waste of have all that excess power that can't be stored or used!
Perhaps more Powerwalls in your future?
RFernatt
Solar/EV Owner/Enthusiast
I have an 11.34kW system in WV with full retail net metering. With an all electric house and two EVs, the power bill is always the minimum $5 grid connection charge. Payback should be 8-10 years. System cost was about $2.83/watt installed on the roof. Panasonic panels and SolarEdge inverter. No battery at this time, but something I'd like to do.
I have around 1000 kWhs per year left over after going through the winter months, but wanted to make sure I could offset 100%.
I have around 1000 kWhs per year left over after going through the winter months, but wanted to make sure I could offset 100%.
As to the original post, at the moment, home batteries still seem to be relatively high hanging fruit, mostly due to initial capital/install cost.
Better environmental and economic returns on investment are more likely to be had taking a home completely net zero+ with conversion to total electric for home cooling, air and water heating heat pumps, induction cooking, etc. and going to full BEV for all personal transportation.
If it is about saving money, with net metering, adding more solar PV almost always makes more sense than going with home batteries. With generation beyond net zero metering, a homeowner is lucky to get paltry wholesale rates for excess electricity.
Utilities will always be able to do battery storage for substantially cheaper than a home resident with economies of scale, though may not pass that savings on to the customer.
There are still some significant outlier cases with potential value to being able to decouple from the grid, such as during natural disasters when power could be out for hours to days and rarely weeks. Right now, all of our Solar PV is useless in a power outage as it has auto shut-off to protect line workers on the grid. Fortunately we live in a low risk zone where outages are rare and very short lived.
There could also be a bit of TOU arbitrage fun in the future if/when advanced TOU plans and metering sufficiently advance to allow electricity to be bought and sold on the market by the second, making home batteries more economically viable.
Better environmental and economic returns on investment are more likely to be had taking a home completely net zero+ with conversion to total electric for home cooling, air and water heating heat pumps, induction cooking, etc. and going to full BEV for all personal transportation.
If it is about saving money, with net metering, adding more solar PV almost always makes more sense than going with home batteries. With generation beyond net zero metering, a homeowner is lucky to get paltry wholesale rates for excess electricity.
Utilities will always be able to do battery storage for substantially cheaper than a home resident with economies of scale, though may not pass that savings on to the customer.
There are still some significant outlier cases with potential value to being able to decouple from the grid, such as during natural disasters when power could be out for hours to days and rarely weeks. Right now, all of our Solar PV is useless in a power outage as it has auto shut-off to protect line workers on the grid. Fortunately we live in a low risk zone where outages are rare and very short lived.
There could also be a bit of TOU arbitrage fun in the future if/when advanced TOU plans and metering sufficiently advance to allow electricity to be bought and sold on the market by the second, making home batteries more economically viable.
TheTalkingMule
Distributed Energy Enthusiast
Interesting, hadn't seen a solyndra setup. These would be great for a canopy/pergola rooftop setup. In Philadelphia we have tons and tons of new construction rowhomes with roofdecks. I'm working on a solar canopy rooftop product based on bifacial glass panels, but a streamlined version of this would be even better IMO. Thanks for sharing.
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