Posted on by xdavegreen

Battery back ups for houses

In 2021, I ordered 3 different home batteries (from Generac, Sonnen and EnPhase at about 15kWh each) to go with existing and new solar-panel arrays (this is how you get the SMART MA subsidy for batteries) for our house and two rental properties we own. THIS IS VERY COMPLEX!

•I was faced with replacing propane powered back-up generators at all 3 houses

•Would have cost $5k per house plus $500 a year for maintenance/service

•The batteries were about $20k each after installation, none was a Tesla Powerwall

•Powerwall cannot both run the house and charge from solar panels together making it useless during lengthy power outages in winter. It is designed for power arbitrage (CA), not back-up generation (MA)! This can be alleviated if you buy the Tesla inverter. A friend just installed two Powerwalls plus this inverter and it cost $23,500 in MA. 

•The batteries+arrays were profitable (5-10% IRR) vs. arrays alone (10-15% IRR)

•A 15kWh battery will run my house (but not the heat pumps) for a day

•Not enough! We have had 3-day power outages at our house

•In late 2021 I ordered the Lightening (with a 100kWh battery = 7 PWs)

•In 2023 I cancelled all 3 battery orders. With V2H on most vehicles by 2025, don’t get a back-up generator or house battery – get V2H!

The V2H and V2G capabilities of EVs are one of the main reasons we need a time of day tariff for electricity in MA. CA has it and it is essential to reducing peaker plant usage on hot summer afternoons as well as saving money by charging your battery at night and using it during the day.

The introduction of this tariff would have a huge impact on greenhouse gas emissions. It would also allow low-income households to reduce their electric bills substantially by, for instance running the dishwasher and clothes dryer (and charging their EVs) at night.

David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.

David Green – the “Green Guru”

David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.

The highly-acclaimed book “Zero Carbon Home”

How David Green, the "Green Guru" cut his home's carbon emissions and utility bills to zero by adding heat pumps, insulation, triple-pane windows and solar panels to make a 15% return on investment. David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.

How we cut our home’s carbon emissions to zero

How David Green, the "Green Guru" cut his home's utility bills to zero by adding heat pumps, insulation, triple-pane windows and solar panels to make a 15% return on investment. David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.

How we cut our home’s utility bills to zero

Our solar panels on the roof of our house. Solar panels are one of the Fab Four of heat pumps, insulation, triple-pane windows and solar panels that got our house to net zero. David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.

Solar panels on the roof of our house

Our heat pumps at our house. Heat pumps are one of the Fab Four of heat pumps, insulation, triple-pane windows and solar panels that got our house to net zero. David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living. Our Bosch heat pumps replaced our ancient AC units. They fit into the same space and electrical breakers as the old AC units. They are saving us about $3,000 a year in heating oil, even after the extra electricity they take.

Our heat pumps

This is the insulation on the roof of our house. The pink fiberglass is 10" thick and has an R-value of about R30. The grey boards are rigid foam ISO boards at about R10 each. Insulation is one of the Fab Four of heat pumps, insulation, triple-pane windows and solar panels that got our house to net zero. David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.

Fiberglass and ISO board insulation on the roof of our house

These are the triple-pane windows we installed in our living room. Triple-pane windows are one of the Fab Four of heat pumps, insulation, triple-pane windows and solar panels that got our house to net zero. Our new triple glazed windows replaced a mix of 1970's vintage single and double-pane units. The insulating value of the new windows is about 3x that of the old ones. Although it is hard to quantify, our new triple-glazed windows have transformed the look and feel of the house, plus we no longer have to sit under blankets to avoid the cold drafts off the old windows in winter. David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.

Triple-pane windows in our living room

Useful links:

The Easiest Way to Calculate Your Home’s Carbon Footprint:https://greenzerocarbonhome.com/2018/07/what-is-the-carbon-footprint-of-natural-gas-heating-oil-propane-and-coal/

Written Answers to over 300 Questions about Zero Carbon Homes:https://greenzerocarbonhome.com/webinar-questions-and-answers/

Finance and Net Zero Energy Terms explained: https://greenzerocarbonhome.com/energy-and-finance-terms-explained/

Zero Carbon Home Website Home Page:                https://greenzerocarbonhome.com

Database of State Incentive for Renewable Energy (DSIRE) https://www.dsireusa.org

Published articles on Zero Carbon and Net Zero Energy:

Department of Energy, EnergySage, “Zero Carbon Home”https://www.energysage.com/project/7230/zero-carbon-home/

Zero Energy Project, “My Zero Energy Retrofit beats my 401k”https://zeroenergyproject.org/2018/09/23/my-zero-energy-retrofit-beats-my-401k/

Cool Effect, “Mr. Green’s Zero Carbon Home”         https://www.cooleffect.org/content/news/green-testimonial?utm_source=Cool_Effect_CRM&utm_medium=EMAIL&utm_campaign=20180814Engage_Testimonial&utm_content=green_CTA

Green Energy Times, “My Zero Energy Pool is a Great Investment!” http://www.greenenergytimes.org/wp-content/uploads/2019/05/GET_May-2019.pdf

Published Presentations on Zero Carbon Zero Bills:

To see a 3-minute interview of David Green by NBC Boston anchor Joy Lim Nakrin, please click here:TV interview

To see a 20-minute TED talk at Harvard Business School, please click here: TED Talk

You can watch a recorded version of my Zero Carbon, Zero Bills webinar here: Zero Carbon, Zero Bills Webinar

Reviews of my “Zero Carbon, Zero Bills” webinar included, “Minute-for-minute, point-for-point, one of the best webinars I have ever attended. Thank you!”, “David is a true inspiration and asset to our community. He inspired us to get solar panels and a new front door”, “This is like a masterclass in ZeroCarbon”, “Thank you soooo much for the sensible advice and your fabulous resources!!” and, although this next comment is a little flowery, it does express the sentiment of many other comments, “Your contribution to Greening America is great and will probably help our survival as a species a bit longer than expected”.

One Reply to “Battery back ups for houses”

  1. This blog post is a fantastic read! I’m truly impressed by the concept of the “Fab Four” to achieve a net-zero home, and it’s inspiring to see how solar panels play a significant role in this transformation. David Green’s credentials as the “Green Guru” are well-deserved, and I appreciate his expertise in energy efficiency and carbon emission reduction. It’s evident that he’s passionate about creating sustainable living solutions and sharing that knowledge with others. I’m eager to learn more about how these four components work together to achieve a net-zero home and potentially reduce energy bills. It’s refreshing to come across such valuable information from an expert in the field. Thanks for sharing this insightful post!

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