I have a 400 amp service, 2 200 amp sub panels. Designing with 2 gateways, one per subpanel. Having to split solar, so one 11400 inverter per gateway. Minimum 5 batteries, 3 on one, 2 on another. Shall see, got to get the plans approved at county first. And then this all is with my 22k generator with 2 ATS switches, one per sub panel. Sure lots of complexity to make all this stuff work correctly together.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Residential Wind Power and Powerwall 2 integration
- Thread starter Jason Bloomberg
- Start date
This is really interesting. I hope you post about it once you get it up and running. It bothered me that we had to limit renewable panel "solar" and batteries to 100 AMPS each, when with 10 Powerwalls we theoretically could draw 292 peak AMPS at 240 VAC and continuous 208 AMPS from our 10 Powerwalls. In reality, as much as I rather have a 400 AMP service and Gateway, we likely will do fine. It means if we need to charge our Tesla during peak house load, we probably shouldn't do it at 18 kW (dual chargers), but dial it back to 7-10 kW, which is what we do most of the time anyways. If it was within our budget, and if it were available, we might have gone with a Tesla Powerpack instead, but for both reasons, it was not an option. I think we will do fine with what we have. I'm really curious how much impact it will have on how much power we will continue to draw from the grid. My hope is to zero that out, but I'm skeptical. At least we are doing all that is within our reach to minimize purchasing electricity made from fossil fuels.
One cannot have a 400 amp service and a gateway. Gateway is only good for 200 amps.
Luckily my 400 amp main service goes into 2 200 amp breakers. These will each feed a gateway. The batteries and solar sets will each be put into 200 amp generation panels. Each of these will drive into each gateway. I want to wire up for max possibility, even though I did not ask the engineer the limits, even in this config. If I had 10 PW's, still well under 200 amps. So I have no idea if in my setup what the limits are. Is it max of PW and solar, or is that a percentage increase also. Maybe Vines can comment. Chances of me every expanding is very low, but never know which is why I am trying to wire for max expansion, with zero infrastructure changes, wiring and panels.
I love it Jason! Very inspiring. As you’ve said, each situation is different and it appears you have optimized your setup for your location.
It’s not breezy often enough in LA to justify adding a turbine as much as I’d like to out of principle (doubtful the city would even allow it), but I get plenty of sunshine year-round to expand my PV system and likewise, minimize purchasing fossil fuel-sourced electricity to effectively go zero/negative on an annual basis.
It’s not breezy often enough in LA to justify adding a turbine as much as I’d like to out of principle (doubtful the city would even allow it), but I get plenty of sunshine year-round to expand my PV system and likewise, minimize purchasing fossil fuel-sourced electricity to effectively go zero/negative on an annual basis.
Here is an video without narration which gives an overall view of our system as it is installed on our property.
A math question. From upthread it looks like your PV and Wind are roughly equal at 16k kwh each per year. 32k divided by 360 is around 85kwh per day.
Ten PW's, as you say, hold 135kwh. You must be using them as true, true back up, because even with wind and sun blasting away you would not probably produce more than 135kwh in a day.
I say this because the math for me, and some other posters, is using solar to (a) power the house and (b) charge up the PWs during the day, then use the PW's at night.
Your system seems to be in a different league.
Ten PW's, as you say, hold 135kwh. You must be using them as true, true back up, because even with wind and sun blasting away you would not probably produce more than 135kwh in a day.
I say this because the math for me, and some other posters, is using solar to (a) power the house and (b) charge up the PWs during the day, then use the PW's at night.
Your system seems to be in a different league.
Here's a Sense (R) screenshot of our combined wind and solar PV production (in orange) and usage (in green) for 2020. The batteries were installed in the end of 2020 and really didn't become functional until January due to a Gateway which got "bricked" during a critical initial update from Tesla during a loss of connectivity. It's a rare thing to happen, but apparently it did, so they sent us a replacement. Also it wasn't until February that Tesla remotely changed settings so that charging could occur with 100% of the available charging from the renewable panel instead of being limited to 5kW (as if it was a single Powerwall). It's working as it should now, and will also function when off grid, to permit charging.
Each turbine produces ~ 4,000 kWh annually, there are 4 of them. Although they are rated at 2.4 each, they may peak at up to 3.3 kW and often in winds over 27 mph sustain production at close to 3kW each. The rest of the production comes from the ~ 8 kw of installed solar PV on trackers.
We use the system as in "Self Powered" mode. This lets us store all of the power we generate before sending any excess out to the grid, and then during low production times of day, draw power from the battery to power our home and cars. Frequently, that results in a mixture of power from the renewable and the batteries at the same time. Example: if the house is drawing 6 kW and the renewable are drawing producing 2 kW, the remaining 4 kW the house needs will draw from the batteries rather than from the grid. When the load from the house drops, or the production increases, then any power in excess of what the house needs will go to the batteries until they are full, then to the grid. If we have a long period of low or no gain, and deplete the batteries, then we draw back from the grid. Will this system permit us to be be potentially fully grid independent? Doubtful, as during the recent arctic blast weather we had for more than a week, we needed to draw back power we banked with the grid. I think people don't realize how much energy it takes to heat a home in extreme cold weather, even when well insulated and using a very high efficiency ground source heat pump. Add on to that multiple electric vehicles. We will know more about our system over the course of the year. For now, it demonstrates that some small scale wind turbines do work with the Tesla Powerwall 2. For us, it works. I'm not saying it is the path for everyone.
We live in a very windy area and have Tesla Solar with 2 powerwall 2 units. I believe if we added a couple of small wind generators (may have to look like yard are to pass HOA) we could be off grid and charge our car at home more. Can you send the details and/or diagram of your system or suggest someone to contact to work on our system? Thank you! Yours is the first system I have seen where everything it elegantly integrated. Mitch
My email is mitch at mitchrice dot com
Being off-grid in an all electric home, with electric vehicles is going to be very challenging. There are 100,000 BTUs per therm of natural gas. There are 91,740 BTUs per gallon of propane. There are 3413 BTUs per kilowatt hour of electricity.
Comparing electric home heating to combustion is not intuitive because it takes a large quantity of electricity to create the same amount of heat as combustion, but because electricity can be made by renewable sources, when it is sourced that way it remains the environmentally better way to do it. This is our approach. We also live in a much colder climate than you do in Santa Rosa, CA. Here in Cheyenne, WY we get real winter with typically a week or two of arctic cold temperatures.
If on the other hand, you heat your home with combustion and/or are in a warmer climate, which you are, the amount of electricity and storage you need is very different than us. One of the things to do is to quantify your present and projected electricity consumption. An off-grid home needs to have enough battery storage to cover the longest anticipated period of low gain, or no gain days, during the highest rate of electricity usage during the year. For us, that would be ideally be 5-7 days during the coldest part of winter.
Something to keep in mind with wind turbines, usually, HOA are not very accommodating of them. We live in an area where generally the minimal lot size is 20 acres, and ours is smaller, "grandfathered" in, with only 9.6 acres. Still, there is enough distance between us and our neighbors so that neither noise nor wind obstructions are much of an issue. We still checked in with neighbors and got their blessings before installing them. They appreciated the courtesy and concern. The result is we are not having to deal with the kinds of resentments others in other locations have had to cope with. Ideally, wind turbines should be at least 300 feet from the closest wind obstruction. Our original two turbines were sited 80 and 160 feet from our house, but were in a "wind trough" due to topography which made that advantageous and working within cost constraints at that time (2012). The second pair of turbines was installed in 2019 with a more ideal siting. This permits the second pair to generate approximately 500 kWh more per year than the first pair. Also keep in mind, turbines are mechanical devices with moving parts which means they will need repairs from time to time. If you install turbines, you want to make sure it is done by someone who will be available to service and support them for ~20 years otherwise you may end up with very expensive "lawn ornaments."
We included wind turbines in our system because we needed to generate most of our electricity during the coldest months, which also have the shortest daylight, and work within a constraint of being smaller than 25 rated kW to comply with Wyoming's Net Metering Law, and NOT become a small scale utility with all the cost burdens that would entail. This is also why we have trackers for our solar PV arrays. We also have experience with both from our prior off-grid home since the 1980's. While I don't have a specific recommendation for who could do the installation and support for any renewable energy projects in your area, I have uploaded a PDF showing the conceptual diagram of how our system is laid out.
The Skystream 3.7 Turbine was made by South West Windpower which went out of business in 2013 after more than 20 years. It was bought out by Xzeres which has since been bought out by HCI Energy in 2018. We "lucked out". Our installer, WYCO Wind and Solar has continued to service and support our turbines despite all of these upheavals. As far as I know they are the only ones really doing that. They have created a niche business supporting what for most people is now an "orphan product." HCI Energy, as far as I know, is selling the turbines only are part of a combined wind and solar industrial site package. I don't know if what they offer would be usable for any homeowner. You can check with them directly. I've put hyperlinks in this reply which at the time I write this are all functioning, but may not in the future. You can contact WYCO and see if they know of anyone else in your area who works with wind turbines or see if they would do work in your area, but I suspect it would be very expensive to have them come from Cheyenne, WY to do work in Santa Rosa, CA. You can also look into other turbines. We picked and have stuck with the Skystream 3.7 because it is very low maintenance and withstands Wyoming winds, thus far on our property of gusts up to 90 mph with sustained winds of over 60 mph. Most other residential scale wind turbines fail under those conditions. When considering any turbine, look at their history of reliability. While many of the manufacturers of residential scale wind turbines no longer exist, the articles and reviews in the now defunct Home Power Magazine which are accessible for free online through their archive, remain very useful and I recommend reading them. You might consider learning about the Bergey turbines, which are one time were considered to be among the best made, but don't come cheap. You could also consider finding a Jacobs Wind Electric which is what we had for our off grid home in Chadron, NE until 2012 when it was lost to a forest fire. Ours was originally built in 1948 and rebuilt by Mick Sagrillo in the 1990's. Here's a video link which you may find useful.
While I appreciate the sense of having plenty of wind to harvest power from, if I were where you are, before pursuing wind, I would see whether or not I could meet my electricity generation needs fully with solar PV. It's costs have decreased while residential scale wind power has increased, PV needs very little maintenance, which wind turbines can be reliable, they remain mechanical devices with moving parts, so will likely need more repairs than PV. Also, it is much easier to find service and support for PV which by its very nature is "modular" compared to wind turbines which really become manufacturer specific installations. This is why we have a "spare" complete turbine and multiple spare components (alternator, inverter board, etc.) for our system. We have these parts in case WYCO ever can't get them. Wind power, while important and appropriate for us, requires a substantial financial and knowledge commitment greater than solar PV, which is becoming ever more "plug and play." Someday, those differences may diminish, but for now they are the practical reality. This is why Tesla doesn't officially support wind power with its Powerwall 2 system even though as we demonstrated, it actually works very well with the Skystream 3.7 and might work well with other wind turbines. I hope this helps.
Looks like Tesla fixed the software issue which let the Powerwalls draw too many AMPS during a Storm Alert. It maxed out at 24 kW (240VAC at 100 AMPS) which is perfect to maximize charging without tripping the breakers. Previously, it was drawing up to 35 kW when Storm Alert activated tripping our 100 AMP breakers, making that feature useless. With 10 Powerwall 2 units, it was a software glitch as it was programmed for 100 AMPS as our home has a 200 AMPS utility service and 100 AMPS renewable energy subpanel. The batteries plus renewable energy panel cannot exceed the utility service rating. I contacted Tesla Energy a few weeks ago and put in a Service Ticket but haven't heard anything back. Communication is not great, but they fixed the problem. Now we can leave the Storm Alert function toggled on when we are away while other8running in Self Powered mode to optimize using our own renewable energy to power our home and optimize our battery backup if the National Weather Service triggers a Storm Alert without the battery system shutting down because the breakers trip from charging at too many AMPS.
Attachments
Last edited:
Technical information about Skystream 3.7 is available at: Skystream 3.7 small wind turbine
Our average annual wind speed is ~16 mph, with speeds ranging from 0 - 70+ mph. Here in Cheyenne, each turbine produces about 4,000 kWh annually. With an average wind speed of 4 - 5 mph, I doubt any turbine will give you useful production. The Skystream 3.7 starts spinning at 6 mph and minimally produces (<100 Watts) at 8 mph. It's optimal production is at ~27 mph where it produces 2,800 - 3,200 Watts.
Before investing in any wind turbines, I highly recommend reading up on residential wind power in the Home Power archive. Look for articles by Mick Sagrillo.
Home Power Magazine | Downloadable Archive | Home
An archive of the complete 31-year history of Home Power magazine. 188 digital back issues capture a three decade history of the renewable energy movement in the U.S. and beyond. Each issue is available for non-commercial use at no cost to registered members of this site.
www.homepower.com
I hope this helps.
Merrill
Merrill
I looked into residential wind power years ago, the problem at that time was you need a minimum of 6mph of wind which I do not have on a consistent basis.
I would say you made the right decision. I would not recommend residential wind power for less than an average annual wind speed at 30 feet of 12 mph. Most posted wind speeds are at 100 feet. We did wind speed measurements near our intended installation locations for 2 years before installing our turbines. They originally were mounted on 33 foot monopoles, which have been upgraded to 45 feet. While higher, such as 65 to 100 feet is significantly better, it would exceed the technical capabilities of the installation and service company in our area. We opted for performance compromises in favor of less costly and local serviceability. We looked into articulating monopoles towers of greater height,but their installed costs at that time was more than the entire cost of the test of the project.
Thanks for the info, ideas, and photos! Are these 10 Powerwall 2s in a fire rated room?
They are in our garage. The system plans were submitted to the county and permitted prior to installation. After installing they system was inspected by the utility (High West Rural Electric Co-op) and the county. Both had to approve prior to the system being activated. Whatever code required at the time of installation, the system is in full compliance. Your code requirements in your locality may differ from ours.
