Environment & Energy
Related: About this forumHas anyone had experience with a solar battery?
I have a company coming over Tuesday, I think they will recommend Tesla Powerwall. Anyone have a solar battery system for their home?
Thanks!
Miguelito Loveless
(4,438 posts)I assume you have solar, how big an array? Avg daily output?
MLAA
(17,165 posts)I have nothing yet, so I will be getting solar panels and battery/batteries. A few months ago I had a couple companies come out and they seemed competent on panels but seemed to know little to nothing on batteries. Both were anxious to have me get the panels and deal with batteries later. That seemed like a red flag to me. Hopefully I will have better luck with the company coming next week.
I hope to have enough solar and battery capacity to power two large rooms (about 400 sq feet each) with mini splits, maybe a small fridge, lights, computers and tv. I figured installing two mini splits is a better way to go than trying to get enough power to operate the existing large AC/heat pump that powers the whole house.
Im looking to have power in the event of city power outages.
What brand batteries do you have? Any general tips for me? Any questions I should be sure to ask the solar company?
Thank you!
Miguelito Loveless
(4,438 posts)but you definitely want the system designed for the PowerWall. Using a PW means something in the choice of inverters and how the system is wired, and can have code ramifications, or ramifications because of utility tariffs (Utility company's HATE batteries, but depending on the state, they have to accept them).
What's the sq footage on your house and what direction is the roof facing? This can affect the energy output and how many panels you needs. The average house uses between 30-35kWh a day (assumes gas heat).
I have a 2600 sq ft house with an L-shaped house with E-SE facing roofs. I have a 20kW array as I am also powering three EVs. I have three Tesla PowerWalls with a total usable capacity of 40.5kWh of capacity which is enough to run my house for a day or two, possibly more if I manage load usage.
What is your average daily energy consumption? How many PVs are they looking to install and what rating for the panels? Also, what is the cost per watt for the job (total dollar cost divided by array size in watts, before tax credits)?
MLAA
(17,165 posts)So we get plenty of sunshine. I am most concerned about air conditioning vs heat 🙂. The house is about the same size as yours. Based on costs, I know it will be pricey. One Option may be to just be able to keep about 800 square feet of it cooled and operating lights, small fridge etc during an outage. Although, there would be quite a bit of comfort in knowing I could be self sufficient for longer periods.
For my whole house the average daily consumption in the summer is about 33kwh. During Dec, Jan, Feb it nearly doubles. Apparently heat pump draws a lot more electricity than the air conditioner. I can manage the winter usage better by bundling up more if needed. But you cant do much about 110 degree heat!
Thank you.
Miguelito Loveless
(4,438 posts)I figured we'd get around to where you live.
The good news is when you need A/C the most, you are getting plenty of power. If you have a South-ish facing roof, you should generate a fair amount of power. I routinely generate 70-90kWh in the Spring/Summer, 40-60kWh in the Fall/Winter, so I can keep my battery charged up.
Have you looked at any of Tesla's solar offerings? The reason I ask is I believe they now sell in AZ, and they have sales/rent options, and they offer discounts for folks putting in Solar/Powerwall at the same time.
https://www.tesla.com/solarpanels
To get a good idea of how much power you can produce, you can use this site (NREL site)
https://pvwatts.nrel.gov
The per watt figure solar should be around $2.00-$2.50 installed.
If you have any questions, I am at your service.
MLAA
(17,165 posts)I will check if they are authorized for Tesla solar panels also. Seems like they should be.
Here is their website. I looked at their solar calculator and then added an estimate for the Tesla batteries. The cost is a little less than I was thinking after tax credit. Will let you know how it goes after Tuesday. They asked for my hourly usage for the last 12 months and I sent them that info.
I really appreciate your help.
http://www.tfssolar.com/
Miguelito Loveless
(4,438 posts)Provided the array/battery is configured so that it only uses solar to charge the battery, and the battery never provides power to the grid. In essence, you may not use grid power to charge the battery, and you may not sell power back to the utility from the battery.
Here is a link about the IRS ruling including a link to the a PDF of the IRS letter.
https://www.greentechmedia.com/articles/read/irs-says-that-batteries-can-take-the-federal-tax-credit
Shermann
(7,358 posts)Miguelito Loveless
(4,438 posts)String or micro.
String means one BIG inverter that ties all of the panels together, and aggregates the power to your home/grid.
Pros:
- Cheap
- Lots of vendors
- Proven tech
Cons:
- Single point of failure
- Requires an optimizer to properly handle shade
- Some people find them unsightly (can be a problem for HOAs).
Microinverters are small, and one fits on each panel
Pros:
- Redundant. Single failure only affects a single panel.
- No optimizer required
- Nothing to mount on side of house
Cons:
- More expensive
- Newer tech (though, so far quite reliable)
- More complex array since you go from a single inverter, to one inverter per panel. 20 panels, 20 inverters.
Best string inverter - SolarEdge
Best Microinverter - Enphase
When a battery pack is added for backup/daily use, you have to make sure your inverters can work properly with a battery, and are hooked up correctly (according to code) to your power panel/grid connection.
Shermann
(7,358 posts)This may be a good assumption, but the OP wasn't clear if an off-grid system is required here.
Miguelito Loveless
(4,438 posts)especially utilities. My view, and just my opinion, is to go grid tied. My reasons are:
1) The grid is your backup
2) Your excess power gets used by your neighbors (though the utility company gets the money in most places). Otherwise once you charge your battery, and power your house, any excess power is wasted.
That a caveat:
Unless you have a battery backup, properly installed with a transfer switch, the loss of grid power means you lose power as well, even during the day, because safety rules require your array to shut down, to prevent "backflow" onto the lines. IF a tree takes down a power line, the linesmen do not want your array feeding power back into a line they are working on.
Of course, if you are not tied to the grid, then no worries. BUT, you must have a backup power supply (generator or battery) to power your house at night and during overcast days.
PoindexterOglethorpe
(25,750 posts)It probably wasn't the very best financial decision I've ever made, but I'm quite glad I did it.
Miguelito Loveless
(4,438 posts)what you pay for electricity, what tax credits you can get, and shade, Solar is either a decent enough investment, or a favor for the planet and your children/grandchildren.
I'm in the middle. My local electricity is cheap (11¢/kWh), but I use EVs so my gasoline cost is zero.
PoindexterOglethorpe
(25,750 posts)Lots and lots of sunshine. Shortly after I moved here, my son visited. We'd been driving around and he'd been silent. When he finally spoke up he asked, "Where are the solar panels?" He was right. They should have been everywhere.
The main reason I might not have made such a good financial decision is that I live in a small place, about 900 square feet and simply don't use very much electricity. Perhaps 8 years ago there was a man in a local store with a temporary booth trying to sign up people for solar. We had a wonderful conversation, and when he learned that my monthly electric bill was not even fifty dollars, he told me flat out that his company wouldn't be willing to install solar for me. A year or so ago, the cost of the panels had come down, and even though my electric bills weren't really much higher, it sort of made sense.
I also think in terms of someday, when this place goes to be sold, whether by me or my son, the solar panels will help it to sell very quickly. Similarly, a year and a half ago when I needed to replace the furnace, I went ahead and got a/c at the same time. I do use it, although it's not that bad here without it. More to the point, when this place is eventually sold, the a/c will help it sell more quickly.
I've already told my son that if he's the one who needs to sell it, just consult with a realtor, price it at about 5% less than what it should go for, and just sell it quickly. Whatever money is realized will all go to him, so he really doesn't need to care about getting the highest possible price. Just sell and go on with his life.
Miguelito Loveless
(4,438 posts)varies depending on the market, so that is hard to predict.
The best case for solar is an all electric home (electric heat pump, electric hybrid water heater, electric range/dryer), with either an EV, or a PHEV (Best pick 2016-2019 Chevy Volt). We were able to reduced out gasoline usage from 800+ gallons a year to <50 gallons with a 2012 Nissan Leaf, and a 2017 Volt (both used). Using electricity for transportation means greater savings, thus faster ROI. The cost of fuel for the average ICE car is about 8¢/mile in my area (central NC), versus 3.5¢/mile for our EV. Areas with higher gasoline prices and/or electricity prices will see greater savings with the solar/EV combo.
At the moment, we are meeting 100% of our EV/home needs, except for heat. When our furnace dies, we will replace with a geothermal heat pump, and that will be the end of our FF consumption.
Our grid is coal-powered, so our array kept about 55,000 lbs of CO2 out of the air, plus a quantity of heavy metals, and other dangerous PM 2.5.
PoindexterOglethorpe
(25,750 posts)And my heat. Sounds like a lot, but my gas bills are not very high, even in the winter. Helps to have a small place.
I don't expect the solar will add much, if any value, but hopefully will make it sell quickly.
MLAA
(17,165 posts)Super excited, I signed contract for 24 LG NeOn panels and two Tesla Powerwalls. They are backlogged so wont get installed for about 10 weeks.
Thanks for all your helpful input. 🙂
Miguelito Loveless
(4,438 posts)Let me know how it goes, and drop me a message if you have any questions.
MLAA
(17,165 posts)I should be able to run everything except the heater as long as not too many cloudy days in a row (usually not a problem in the desert.). Going to add a couple mini splits for two bedrooms to use if needed instead of big central heater/air conditioner in case of outage.
🙂
MLAA
(17,165 posts)self generated power vs the cost savings. I live in a desert so the idea of going without electricity in 110 degree heat weighs on my mind 🙂
Miguelito Loveless
(4,438 posts)and the company is in your state, if memory serves.
https://www.zeromasswater.com/
MLAA
(17,165 posts)This Looks fascinating and it says it works with under 10% humidity, which we are about half of the year. I am going to check it out. Have you tried it?
Miguelito Loveless
(4,438 posts)and I had been considering a condenser-based solution, which is actually expensive, complicated, high maintenance, and requires filtering/treatment of the water.
Here is a video of a guy who just installed one recently:
Ben does a lot of Youtube videos on EVs and solar.
MLAA
(17,165 posts)And yes, the company is located in Tempe (suburb of Phoenix) and only 1.5 hours from me. The only downside I heard on the video is that it is pretty loud, though their next product release might improve that.
Ill need to find out how much of my roof space will be needed for the solar panels, but the two water panels didnt look too big. 🙂
Miguelito Loveless
(4,438 posts)and he said they were looking into the noise issue.
Oh, another useful tool, if you haven't seen it.
https://www.google.com/get/sunroof
PoindexterOglethorpe
(25,750 posts)I managed quite well my first ten years here without a/c. I don't have western facing windows, which is huge in the summer. I got good at opening windows and doors as it cooled off, then closing them as it got warm in the day. Indeed, on occasion people thought I already had a/c.
I have lived in places where a/c is pretty much a necessity. Tucson, Phoenix, the Washington DC area.
My son currently lives in Fairfax, VA, just south of DC. When I told him that my first three and a half years there (I was in Alexandria, VA at the time) I didn't have a/c, he was rendered speechless. In 1969 I moved into an apartment in one of the many complexes that had been built in the 1940s to accommodate the thousands of people who moved there for the war effort. It was brutal without a/c. My second summer I purchased a window fan which helped some, but it wasn't fun at all.
Fortunately, Santa Fe is at 7,000 feet, which makes it wonderful. It always cools off at least into the low 60's at night. I never did get around to buying a window fan as I'd had in Alexandria, but it would have made things quite wonderful here without a/c.
I don't even need it full time, just for a few hours when it gets warm enough that I feel like I need a cool down.