Going Beyond Rooftop Solar – Making the Decision 

By Nick Hein, 2/26/20

A year after Ken and Barb installed their solar array with the help of Legacy Solar Co-op, it’s been performing even better than expected -producing more than 100% of their electric needs. That’s gotten them thinking, since their utility doesn’t pay them as much for the excess, they’d like to use it to offset (or eliminate) their natural gas usage. They wonder if replacing their current furnace, water heater and appliances with the most efficient models available, their rooftop array could produce all the energy they need to use in a year. Then they could completely disconnect the natural gas service.* So it looks like they could become 100% net-zero, and now the question is whether they should. Let’s join Ken and Barb one evening as they discuss it.

“Barb, I’ve been reading about something called ‘Deep Energy Retrofits’ where homeowners upgrade their insulation and mechanical systems so their solar array can provide all the power they need. It looks like something we could do.” “OK, I can see how that would be a good idea for the planet since we’d be completely free of fossil fuels, but does it make sense for us financially?” asks Barb. Ken replies: “I’m not sure yet, and it probably depends on how much we spend on the upgrade, but I read an article from one person who did it and found that it paid a better return than his 401k. He also liked the fact that the return was more predictable and the investment was going into his home.” (1)

“How would we get that kind of a return Ken?” “Well, there are 2 parts –insulating the house, and upgrading the systems. We’ve already insulated the walls and roof with the best available materials and installed an ERV to keep the air fresh. That leaves the windows -some of them are newer but the old ones leak and fog up every winter, and new ones won’t. The mechanical systems we’d be replacing are the gas furnace, air conditioner and water heater with electric heat pump versions. We’d replace the dryer and stove with more efficient electric ones. We’d need to run 220V electric lines to each of them, and probably upgrade the breaker box for the increased capacity.” Ken responds.

This is starting to sound pretty expensive to Barb. “How much will all of this cost?” she asks. “I’ve only seen rough estimates, but it looks like it would range anywhere from $12,000 to 15,000 depending on the models.” Ken answers. “We don’t have to do it all at once, but the sooner we convert everything to electric the sooner we can stop paying the gas company. With what we’re spending on gas and rate increases, our payback time would be about 15 years.” Barb asks: “What if we move before then? Won’t we lose some of that investment?” Ken has looked into this “It turns out that efficiency upgrades increase the home value, so we’ll get the payback when we sell. If we stay here, being net zero means our energy costs will be nearly constant when we retire and our income is fixed.”

“Our car is ten years old now, should we go electric with that too?” Barb asks (1). “I thought about that, it doesn’t affect the payback time since we’d be replacing it anyway and electric cars cost about the same as their gas equivalents now. It means we might have to buy some electricity to keep it charged, but that’s still less than buying gas and they have lower ownership costs. A charging port is only a few hundred dollars, we might as well put that in with the upgrade.

Ken continues: “That reminds me, money isn’t the only consideration for these changes. We’ve been hearing more every day about how we need to eliminate fossil fuel use. With this upgrade we could become 100% fossil-free and energy independent for less time and money than we spent on our bathroom upgrade last year. I know how my cousin in West Virginia goes on about the damage that natural gas fracking is doing there. And your cousin in Northern Wisconsin lives right next to that fracking sand mine that’s made their life so unpleasant. We’d stop giving money to the companies that do that.”

Ken adds “Being all-electric comes with comfort and convenience too.” Barb has been thinking about this. “Yes, I love our smart thermostat that you can control over the internet from anywhere. Do these electric appliances offer that too?” Ken answers: “Where it makes sense they do. Water heaters can be turned down when you’re not using them and scheduled to come on so you have hot water for your morning shower. Dryers can be scheduled to run at night when electricity is cheaper. I know how much you love the instant heat from gas stoves, but now induction cook tops offer that too.” “What about the drafts and dry air we have in winter. Can we do anything about that?” Barb asks. “Since the insulated windows don’t fog, so we can keep the humidity higher. A heat pump furnace/air conditioner will move the air more gently so we won’t even feel it.” Ken responds.

Barb is convinced that they should look into it further. “It definitely sounds like we should do this, but I’d like more information on our options. Who do we talk to about getting started?” “I’ve read that there are contractors that specialize in deep energy retrofits, I’ll find out if there’s one near us Barb.” “Thanks Ken. You know I always knew our home could keep us comfortable, but I think this upgrade will make things better for everyone.

Next episode: Going Beyond Rooftop Solar –Taking the Action


1. “My Zero Energy Retrofit Beats my 401(k)” by David Green. Retrieved 30 January, 2020. (Ken and Barb are not finance professionals, and they will certainly consult one before making changes to their investments –you should too.)

* Most municipalities require that all homes be hooked up to the grid, meaning you’ll always have to pay the connection charge –check with your local authorities.