This post will be a bit unusual, as both of us will chime in.
From Elizabeth:
In May, we were finally able to have solar power installed on our house. We used a local electrical company called Got Watts? and we were beyond satisfied with their services. The initial paperwork took a couple of weeks, the actual installation took two days, and PG&E (our local power company) took over a month to finally give us permission to operate. It’s been operating now for a couple of weeks, and we have an app on our phones that shows us how much power we are producing, consuming, importing, and exporting; the data is starting to stack up and that shows us further ways we can increase our energy independence.
I want to be totally transparent about our process and our feelings about it, so that you can determine if this is the right way for you to move forward. I believe that solar is something we will all eventually have to embrace and install on our homes, so the more we know, the better. First, the money side of things: The cost is still prohibitive, and though in California there is a tax break that will fund about 20% of it, it is still an absurd out-of-pocket expense. We paid over $20,000 for this system, which included a new electrical box (ours was from 1949 and did not have the capacity to handle the new 7680 watt PV system). This also included all permitting, and a discount because we paid in full by check. We used an inheritance from Tom’s parents to pay for the bulk of this. If we had not had that money, we would have been saving for a much longer time. To me it is clear that solar needs to be subsidized by the government so that it is viable for everyone. I am aware that this would be an enormous amount of money for the government to provide. We can argue about the true cost of climate change another time.
As for my philosophy, I do not think that solar alone is going to meet the world’s electricity needs, especially as global temperatures increase and those in the hottest, most humid environments begin to feel the health effects of it. We will need everything at our disposal to provide power - that is, everything EXCEPT fossil fuels. If we cut out oil and gas, what’s left? Wind, solar, existing hydro (although with the water crisis in the west, that is becoming a fragile technology), and nuclear power. We will also need a way to store power when it is not being produced, in the form of bigger, more efficient batteries. Our home system does not have a battery for back-up power, because it would have doubled our price and we simply could not afford it. Plus, it wouldn’t have been able to store much more power than what it would take to run our refrigerator for a day. When the technology improves and the price drops, we will consider adding a battery for back-up.
The solar industry also has its share of problems. The process of making solar panels is a dangerous one; it uses many chemicals which are hazardous to both the people working on them and the environment when they are discarded. We currently do not have good battery recycling in place, and that is an urgent need. However, as I’ve often said, we have to begin now to make better choices. They may not be perfect choices, and there are trade-offs to everything, but we will continue to make even better choices as they become available.
With all of this in mind, here is some data for you to consider. Below is a typical day for us, one in which we are not charging one of our electric vehicles.
You can see that the bulk of the power is generated in the middle of the day, just as you’d expect. However, we are consuming small amounts of power over the course of the day, leaving quite a bit of the midday-generated power to go to the grid; alternatively, this means that we are buying power from the grid at the times we are not generating it. This particular day, though warm, was not hot enough for us to use air conditioning. On this kind of day, I figure it’s all a wash - the good we are doing for the grid at large, evens out our usage at times when we are not producing.
But - what happens when we plug in our electric cars to charge overnight? We have always charged our cars at night because it costs us less money to buy electricity at that time (and, we’re not using them at that time). Here is an example of that sort of day.
You can see that we are needing to pay to import energy from the grid overnight. This is one of the big challenges with solar, or many other kinds of renewable sources of energy – absent some kind of storage solution, you need to align power generation with power consumption every minute of the day.
From Tom:
One of the questions we’ve wondered is whether it would make sense for us to shift our car charging pattern to more closely align with the solar generation pattern (assuming that having a car plugged to charge in the middle of the day is logistically feasible). Like many questions, the answer is complicated, and depends on your frame of reference.
To look at it from an economic standpoint, we needed to look at the way PG&E is charging us for power and crediting us for power that the solar system is generating above what we’re consuming. After downloading our usage data and working through some spreadsheets, we’ve come to the conclusion that aligning our car charging with the solar generation (vs. overnight) probably doesn’t make much of a difference, and we might actually make out a little bit by charging it overnight.
Our usage data shows that our cost per kWh from PG&E is the same as the credit per kWh that we get when our panels are producing more than what we’re using. Those rates vary by time of day — right now, about $0.18 per kWh between midnight and 3PM; about $0.36 per kWh from 3-4PM and 9PM-midnight, and $0.46 per kWh from 4-9PM. Since most of our solar power is getting generated between 8AM and 4PM, we’re getting credited at about the same rate as we’d get charged if set the cars to charge between midnight and 7AM. We might make out a little bit charging in the early morning, and then selling back to PG&E at that higher 3-4PM rate, but that’s not a big difference.
Even though the time of day we choose to charge our cars is probably an economic wash, there is something that feels odd about charging the car when our panels are not generating power. Is there an environmental impact? Charging our car overnight means that we’re pulling power from the grid, with whatever sources of electricity the grid is using at that time. While we talk about getting our power from PG&E, technically we’re getting our power from MCE Green Energy, which means that 60% of the electricity is getting generated by renewable sources (solar, wind, hydro), but with our overnight charging pattern, it’s likely that the electricity we’re using is getting generated by hydro and some set of non-renewable sources. If we were to charge our car midday, we’d know that a bulk of the electricity to charge it comes from our solar, as opposed to those other sources.
All told, at this point we’re going to keep our overnight car charging pattern. This research has led us to a slight adjustment (starting charging at midnight instead of 10PM), so that we can avoid the higher 9PM - midnight rates. There’s also the convenience of charging the car when nobody is looking to drive it.
Of course, we’re also only about a month into this. It’ll be interesting to see how our electricity generation and usage varies over the course of the year.
From Elizabeth:
What I’ve realized, and may seem obvious to many of you, but it certainly wasn’t to me, is that the power we are generating from our solar panels isn’t coming directly in to our house. It goes into the grid. If we were on a homestead somewhere, and we were not connected to any municipal power company, then we’d have our appliances connected directly to the solar panels. At night, lacking a battery stack, we’d have to use candles or oil for light, and a wood fire for heat (also not terribly sustainable). Because our house was built to be connected to the grid, the power we generate goes into the grid. We are still buying all the power we need; however, we are earning back the same rate for the power we generate.
This feels a little disappointing. We are not energy independent. If PG&E decides to cut the power in order to curtail the chance of a fire on a very hot, dry, windy day, then our power will be cut, too. If a terrorist attacks our power grid, we’re going to be out of power just like everyone else.
However, the good news is that we are contributing. The amount of power we generate using the sun replaces power that is being generated by other sources. Here in California, a lot of our power is provided by solar, wind, and hydro plants, but we do also use a lot of natural gas and nuclear for electricity generation. Here is recent data from EIA (US Energy Information Administration):
For information about your own state, you can visit EIA to determine how your electricity generated. HERE is the link.
This whole process has been an interesting one. We have learned a lot, and still have more to learn, but I hope our experience will help you make a more informed decision when it comes time for you to consider your own energy footprint.
Edit 7/13/21: Got a summary from Enlighten for the second half of June, and thought this was interesting:
