Posted in decarbonization, electrify everything, energy efficiency, home heating, no fossil fuels, solar

My Solar-Powered Frack-free Home

About our house

We wanted a frack-free, all electric, emissions-free home. So when we needed to move, we decided on a small house, a classic Philadelphia row-home offering about 1300 square feet of living space.

Getting into hot water

When we removed the gas hot water system, we replaced it with an on-demand electric system, with no storage tank. The main benefit is that water is only heated when needed. Another benefit is that this freed up space in the basement. 

[include research about calculating size]

Everyday needs

We replaced all the appliances with efficient electric ones – the fridge, the stove, the washer, the dryer, ceiling fans & double-pane windows. The fridge has a mere 10 cubic feet capacity, enough for the basics for our 2 person household, but not enough to stockpile! Though people with induction cooktops swear they don’t miss their gas stoves, we opted for a basic glass topped free-standing electric oven / range. The washer is a front loading machine; the electric dryer has heat pump technology and needs no venting to the outside; it drains water into the laundry sink, much like the washer does. The ceiling fans do a marvelous job circulating air the 9 months of the year when our windows are open; so much so that we haven’t missed air conditioning.

garage-wall
garage wall with electric panel, solar inverter, and EV charger

Oh, another feature of this smallish house is that it has a 2-car garage. Since the 2 of us share the one all-electric car, we have space for a variety of bikes in the second garage, adding to our multi-modal zero-carbon transportation options. How often does one get to show off a garage wall, complete with EV charger and solar inverter?

Wintertime needs

We also removed the gas boiler, which once pumped hot water thru the house via radiators. This too freed up space in the basement.

Insulated exterior wall using Ultra Touch denim insulation batting

We insulated the basement ceiling, for a warmer first floor. Since our rowhome has neighbors on both sides, we focused on reducing the drafts along the exterior walls. With new windows, and newly framed exterior walls, we added insulation to the exterior walls.

We’ve made the first floor living space so air tight that we often end up opening a window after a shower. There are plans to replace the non-functioning ventilation fan. And so far, have found that the inside temperature only drops by a couple of degrees overnight, even with the space heater off during the night. It seems humans create heat too, which can maintain the heat in a tight space. I’ve heard it to be equivalent of 100 Watts per person. For now, we plan to ride out the winter using space heaters. Next year, we’ll consider investing in a ductless mini-split system.

Powering it all with rooftop solar

Even before we made an offer on the house, we checked for interconnection issues on our electric utility, PECO’s map for interconnecting distributed energy resources (DER). This was in April 2017. The sellers disclosure gave no date for the roof, and the home inspection report stated that the roof was in fine condition, so we signed for it in June 2017. When we finally got a solar installer to assess how much solar this roof could hold, now November 2017, we were advised that we needed a new roof. Having never needed to replace a roof in all the houses we’ve lived in, we spent the winter finding a roofing company who would do the job. Finally, in May 2018, the roof was recovered with another layer. Another quote and another site visit by another solar developer and by July, we’d signed the contract. What were we getting?

In terms of equipment, we were getting 22 panels, each rated for 305 Watts, plus 22 optimizers, one inverter, one AC disconnect switch and one PV production meter. The optimizers, one for each panel, ensures that if one panel fails, or has cloud cover, the others keep on generating. 

The system would be 6,710 Watts (22 x 305), generating 7,811 kWh annually, averaging about 650 kWh monthly.

The fully installed system cost was $19,459, which works out to $2.90 per Watt (19459 / 6710).

We get a 30% Federal tax credit, meaning 30% of the system cost can be deducted in April 2019 when we submit our 2018 tax returns, a value of about $5,838. This means our out-of-pocket cost would be $13,621.

I remember when I bought another house, about 13 years ago. We got proposals from 2 different solar developers, both around $18,000 for a 2,000 Watt system, which translates to $9 per Watt. Compare this to the $2.90 per Watt we obtained today! Prices have indeed dropped.

People have asked, but prices will keep dropping, right? So we can wait a few more years to get a better price? Afraid not. Though prices for the equipment have gone down, a large portion of the cost is the installation, which is all local labor. We need to remain fair to the work force climbing ladders and walking on roofs in all weather.

Looking at a recent electric bill, our current electricity rate is $0.13517 per kWh, the sum of distribution, generation & transmission charges ($0.06710 + $0.06275 + $0.00532).

Our rooftop is expected to generate about 7,811 kWh annually. At our current electricity rate, this electricity would be valued at $1,056 annually (7811 x 0.13517). This is $1,056 that we won’t have to pay each year.

Assuming this system will remain on the roof for about 25 years, ignoring degradation of production and increasing electrical rates which could easily balance each other out, the electricity this system could generate would be 195,275 kWh (7811 x 25) and valued at at least $26,375 (1056 x 25).

Over the 25 year life of this system, it would generate 195,275 kWh, which is equivalent to an electric rate of $0.0698 per kWh (13621 / 195275). About half the rate that we’re currently paying. Turns out we’re both lowering, and locking in our electricity rate for a while.

Since we paid $13,621 for the system, and annual generation is worth $1,056, the system would pay back for itself in 12.9 years (13621 / 1056), after which, we’d have 12 years of free electricity. Return on investment would be 7.75% (1 / 12.9). So much better than money in the bank!

And the best deal? We can claim to reduce 5.5 metric tons of CO2e emissions each year, for at least 25 years.

So, invest in the local energy generation potential of your rooftop. Having lived in this all-electric house for the past 9 months, our electricity usage has been 6,000 kWh. I can say the experiment of living in a frack-free, emissions-free row-home is going well.

I’ll gladly answer your questions; please write me!

 

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enjoying a zero-waste low-carbon voluntarily simple life in mt airy, philadelphia, zip 19119

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