My first year with Solar Power

I've been waiting to write this post for a year. On Nov 15, 2015 my Solar Array on my roof was activated by Seattle City Light. I have been collecting data for a year now and wanted to share how it's working out.

But to cut to the chase, I think everyone should consider getting Solar Panels. It's magical to have something on your roof generating electricity. Even in a place like Seattle the numbers make this very sensible. If I had a bigger roof I would have put on an array sized big enough to take us off the grid. But that will have to wait for panel efficiency to double from my current 280W panels to 500-600W or for roof replacement with the Tesla Solar Tiles.

What prompted me to get Solar? Getting my Tesla. Once I started on the electrical path to driving, I decided I wanted to drive off the grid. I had a local Solar Installer, Puget Sound Solar, do a bid and decided to move forward.

However, there is another critical part of the equation. I replaced every single light bulb in my house with LED lighting. This alone cut down a pretty significant amount of energy. I also invested in a smart thermostat which helped too. 

The Numbers

Lets start with some numbers.

But to first orient you with numbers lets understand how electricity is measured and how that translates into price.

Let's take a 60W incandescent bulb. If you ran this bulb for 1 hour you would consume 60 Watt hours (Wh) of electricity. At 12 cents per kWh in Seattle, that amounts to less than a penny. But if you run that light bulb for a year you would be using 526 kWh or $63 per year. 

526 kWh of energy can drive my car 1,800 miles or 80 round trip commutes for me to work.

Incandescent bulbs suck. You can replace a 60W incandescent bulb with a 10W LED bulb that produces the same or more light.

That electric meter on the side of your house is measuring how many kWh you are using. It counts up and each month you are billed for the difference.

Prior to getting Solar, we were consuming  19,158 kWh a year. That's quite a lot of energy for a 4 bedroom household. At 12 cents per kWh that's $2,299 in Electricity. Energy here in Seattle is pretty cheap, and our energy is 100% hydroelectric.

We got an estimate for a 5,415 kWh system. But because that system won't get sunlight all year due to trees, shade and some other factors it was estimated to produce  4,889 kWh a year. That means that the system should generate 4,889 kWH of electricity or $586.68 per year.

So if you follow the math (19,158 kWH - 5,415 kWh) = 13,743 kWh.

But I did better than that. In addition, as I mentioned, I got a Tesla and that would in turn increase my electrical usage. The Tesla used 2,737 kWH in Energy (cost me $329 to drive about 9,000 miles in the first year) which breaks down to about 305 watt hours to drive one mile. That's not bad. 

So, with that, I should have consumed (13,743 kWH + 2,737 kWh) = 16,484 kWh.

But instead, my annual energy usage came out to 11,512 kWh. A net reduction of 40% of energy usage.

As I mentioned this came from:

  1. Moving to LED lights for all our lights (I estimate about 3,000 kWh in savings)
  2. Changing our behaviors and Appliance Load

I don't know about you, but I am dammed impressed. Here are some interesting numbers.

This is Solar production for the past year

This is a chart of Energy Usage for the past year. April and Sept are low-energy months as there is no need for heating or cooling.

And here is a chart of both plotted together

You can see how production is affected by the amount of available Sun. But what is surprising to me is that there is solar production (albeit small) between Oct and Feb). 

It's also interesting that Puget Sound Solar estimated that I would generate  4,889 kWh in energy and we came in at  4,883 kWH. 99% is pretty good.


And here is how our devices break down

The interesting thing about usage is that AC came in a lot less than I expected. Our Furnace actually uses a lot because we run it for 10 min every hour 24/7 to bring in outside air so our house can "breath" but also to keep the house temperature even. Our Dryer is a big driver of load as well.

Why is Other so big? Well the device that we use (called an eGauge) to measure the load of different circuits in the house can only measure 6 circuits. I wish it could tell us everything as I am pretty curious about what drives usage. I may get the Sense which seems much "smarter". Our baseline home usage appears to be in the 200-300W range meaning that's 2,000 - 3,000 kWh a year to simply keep our house running (fridges, electronics, outdoor lighting, pumps, phantom draw, etc).


A conversation about Solar always involves cost. I will just break down my own cost so you can see how it breaks works out. Every state will result in different numbers as every state has different incentives. Here in Washington, we are a very solar friendly state with great incentives and net metering.

There are 3 ways you can save with a Solar installation.

  1. Federal Tax Credit (30% of cost) - This is a Tax Credit, meaning you reduce your tax bill by the amount of credit in the year you install it. So if you owe $10,000 in taxes, and you have a credit of $2,000, you now owe $8,000.
  2. Net Metering - most people are generating excess energy during the day, as such any excess is pumped back into the grid. your meter "spins backwards" and the utility credits you what they charge you. So in my case, I get 12 cents for ever 1 kWh I generate in excess of what I use.
  3. State Tax Incentive - the state of Washington pays me  39 cents per 1 kWh that I generate. This is because I used Washington made panels and inverters. Otherwise you get paid much less. Solar is so popular that the state had to reduce the incentive from 52 cents to 39 cents as they are running out of the money they set aside to pay people. This incentive expires in 2020.

So with that information here is my payout.

I cheated a bit and calculated my energy savings not based on my net metering calculation for solar generation, but based on the difference between what I consumed before and after we got Solar. To be fair I would need to add in the cost of all the LED bulbs I got, but the math is close enough and will be at worst off by a year.

Based on this, my capital expense of $24,000 will be offset by $20,000 at the end of 2020. So that leaves $3890 that will get offset to $0 by net metering in a few more years after that.

If we consider the lifetime of the panels (25 years) then the system will have generated $10,000 to $15,000 in profit.


Why does this all matter? More than ever, our family is looking for ways to help the planet out. If we can reduce our energy footprint by 40% and make money doing it, you can start to see that the economics of renewable energy start to look pretty good. For something on my roof that just sits there making money....

In fact, it appears humanity may have reached peak fossil fuel usage.

With Elon now in command of Tesla and Solar City, and their new roof tile project, you can bet that more and more of our homes will turn into their own independent energy factory.

Cost keep coming down, efficiency keeps going up. 

Consider getting Solar. If you do, and live in Seattle, I recommend Puget Sound Solar.