Long Power Outages
For most of us in the South Skyline area over the last couple of years PGE's electric service has become visibly less and less reliable. Even PGE's own reports clearly show this, each year, by every metric the service quality has gone down. This manifests itself as more and more outages of greater and greater length. Where outages used to be measured in hours, now they go on for days, or if you have bad luck, weeks. What's distinctive about these outages is that they tend to be regional in character, impacting a great many residents in multiple areas. The causes of this problem are threefold: the increasing extreme weather we are experiencing of late (fire, excessive heat, excessive rain, snow), PGE's aging infrastructure and financial limitations.
Now most people up here rely on a mixture of power sources: PGE, Solar, Batteries, Propane Generators, Gasoline generators, burning wood. And quite a few neighborhoods in the South Skyline region have always been "off the grid" and need no PGE at all! That said, the changing conditions of late affect almost everyone. We note a couple of things happening at once:
Power outages are often regional, affecting many people in a patchwork over a wide area.
Notice though how the factors above interact with power methods:
In other words, extreme weather over longer periods of time can impact power supplies for most residents no matter what the choice of power is! So how should we set up our houses to weather possibly repeated 1-2 week climate/outage events allowing us to maintain our lifestyle without going broke? In the following we focus on electricity only, considering mountain life and explicitly looking at more frequent long power outages.
How much power do I use?
Before we get into solutions, you need to understand your power consumption. Start by looking at PG&E’s website and looking at your consumption. You can get a sense of what you use by month. You can drill down and see what your “high power” days are, typically reflecting some combination of A/C, car charging and water pumping, all high electricity use activities. That gives you a sense of what your maximum typical consumption is. However, keep in mind that any pumps or other electric motors you have will use double their normal current right as they start up. So you can have sudden spikes of power for a few seconds that you have to account for as well. Read the manuals for any larger electric devices you have to figure out their peak loads. This will tell you how much electricity you have to account for when there is no power. Note that this is different from the amp ratings on your panels/circuit breakers. These are set up for a worst-case scenario of everything being on at the same time plus a safety margin. The safety margin is because if your PGE voltage drops, you will use more current. In real life you would never reach these levels. However, when setting up a system that is code compliant, things like transfer switches will have to set up to handle these maximum theoretical loads, even if your actual power sources never produce that much, nor you ever consume that much.
Once you’ve figured this out, you might want to ask if you can optimize your power consumption. Do you have all LED light bulbs? Energy efficient appliances? Thermostats set optimally? When do you charge a car? All these things can materially improve your energy consumption and reduce your power bill even without a power outage. Doing this is a good prerequisite for solving for long power outages.
Grid + Generator:
Let’s start with a simple scenario. You just have PGE. In general the simplest thing to do is to have a generator to provide power when there’s nothing from the grid. In thinking about this option, you need to ask two questions.
(1) Do you need the generator to come on by itself without you there? The key point is, do you want the power to stay on by itself, or is it ok for it to require manual intervention by someone (like you), keeping in mind the house will be dark until you turn it on. If you want the power to come on by itself, you need a transfer switch, which is installed between the PGE service entry and the main panel, and then connects to the generator. The transfer switch detects that PGE is gone and turns on the generator. When the power comes back on, it switches back to PGE and turns off the generator. This is very convenient and reliable. It does require you to purchase the transfer switch, and it requires the generator to be sized sufficiently to replace the entire load. These switches generally cost less than a thousand dollars. PGE sometimes offers programs to subsidize installation of transfer switches. Also, a transfer switch implies a permanently installed generator, which is generally larger and more costly than a smaller, portable generator. Furthermore, the installation should, theoretically at least, be properly permitted by the county. A high-quality system, with both generator and transfer switch, for example from Kohler, will run around ~$10K installed.
(2) Do you want to run the entire load of your house, or only part of it? The issue here is how large a generator do you want to pay for? Oftentimes there are some activities that make no sense when running the generator, like charging an electric car, etc. If you want to get fancy, you can redo your panel to have one subpanel for things you want on the generator, and one for things you don’t. But that requires extra electrical work. For many people this is simply a matter of not turning certain things on while the generator is running. If your generator is truly of limited capacity, then you might manually plug certain things directly into your generator and power only a few limited items.
Obviously, how you do this is a function of your budget and your willingness to fiddle around with things. If you have a very small house the more manual options may make sense, in a larger house you will want things more automated. Also, as power outages get longer and longer, it will become impractical to “camp out” with only a few items powered, and you will need to make the investment in a setup that can power your lifestyle for longer periods of time.
In choosing a generator, there’s a tradeoff between propane and gasoline. Propane is quite convenient. The only gotcha is that during long regional power outages in winter, propane becomes in short supply, and the heavy propane trucks may have a hard time getting onto your property to refill the tank. So you have to tightly monitor your propane supplies and make sure you get refilled. Gasoline on the other hand often requires more frequent refueling and monitoring. Usually the smaller generators are gasoline powered.
One advantage of the permanently mounted generators is that they will automatically exercise themselves every week. This is important because an internal combustion engine needs to run regularly. If you have a manually operated generator, and you forget to turn it on regularly, when the power is out, you may be in for a bad surprise if it doesn’t start.
During longer power outages you also need to consider that the generator will need at least oil added, if not a full oil change. A weeklong power outage is the equivalent of driving your car for 5000 miles, so it’s a similar maintenance interval. To control costs you should learn how to do the oil changes yourself. Again, you have to monitor the generator to see how long it’s been running and shut it off to do the timely maintenance.
Another gotcha is that especially the bigger generators use approximately the same amount of fuel no matter how much or how little load you have. This is partially why a lot of fuel gets consumed. A good size house can gobble almost $100 a day of Propane to run the generator. Some people resolve this by only running the generator some of the time. Again this depends on when people are home, and if you have things like network gear or medical devices or aquariums that require constant power. One good technical fix for this is to have batteries. If your house has batteries, and you have a modern controller like the Franklin A-Gate, then you can have the controller run the generator only to recharge the batteries and turn it off otherwise. This means the generator will run a few hours a day instead of all day. That saves a lot of fuel and maintenance on the generator. The downside of this is the very considerable cost of the batteries. So this probably doesn’t make sense without a solar system (see below).
If you are running computers and other electronic devices, you need to consider the quality of power the generator creates. First, when the generator comes on, there will be a 5-10 second gap while it starts, where there will be no electricity. Second, many generators produce “dirty” power without a good sine wave, that can damage your equipment. Generally with most generators you need to protect your electronics with small UPS devices that produce a “square wave output”. You need the UPS to explicitly state that it produces “Square wave output”, not all do. These will both bridge the gap while the generator starts up and produce clean power for your electronics. One advantage of the more modern battery-based systems is that they do produce clean power, and having a battery smooths out the transitions between power sources.
Summary: if you need to power your house all the time, with little manual intervention, spend the $10K and get yourself a proper generator and transfer switch. If you have a small house and budget, can live with only partial backup, and have the skills and discipline to manage the system in a manual way, a smaller generator is much cheaper. No matter what, you will need to monitor and properly service the generator. And it is quite expensive to power your house off the generator day after day!
Solar + Batteries
So what happens if we get solar? In California traditionally the NEM-2 standard made for very simple systems. Basically your solar panels are connected to the grid. In the daytime you run off of solar energy, and any excess electricity gets fed back to PGE who pay you for it. At night you run from PGE as before, and the credits you earn in the daytime pay you for the usage at night. The problem with this system in a power outage is two-fold. Obviously, you have no power at night. But more problematically, the entire system shuts off if the grid is down. This is because if there is a power outage, and the solar panels remain connected to the grid, some power is fed back to the grid which would be a hazard to any crew trying to restore power. As a result during a multi-day power outage a traditional solar system is completely useless. It doesn’t help at all.
The first order fix for the problem is to have batteries. The solar cells charge the batteries in the daytime, and then you can certainly run overnight. The main problem is that even with big batteries, they will run out of electricity after a while. Many people solve for this by reducing their electricity consumption, just as with running a smaller generator. If you use little enough electricity, and have enough batteries, then you can make it through enough bigger outages. Keep in mind that the batteries are expensive, 10K-20K each, and you will require more than one, and require proper permanent installation. Like the solar system and a permanent generator/transfer switch, all will require building permits.
An additional wrinkle is that California has now moved to NEM-3 for new installations of solar power, which drastically reduces how much PGE will pay for electricity from solar in the daytime. This destroys the traditional economics of a simple solar system. In fact this is another reason to buy batteries, because now excess electricity can be stored and sold back to PGE at times when they pay a higher rate.
In the mountains an additional consideration is if your land/house offers enough space for enough solar panels pointed directly at the sun enough of the time. This is a problem given mountains, trees, and house orientation. The difficulty is that solar panels rapidly lose efficiency if not pointed directly at the sun for a good portion of the day. This is a major issue. Very bad weather will reduce power generation by 75%. Having the panels pointed the wrong way will also reduce efficiency by 30-50%. The solar company will address this partially by overprovisioning the panels, which requires more $ as well as more space for them, but this will go only so far, unless you have a LOT of panels. In practice this may mean that in winter you have to rely on the grid on days with very bad weather.
The solution to this dilemma is to couple the solar panels and batteries with a generator. Now the system can balance between all power sources: solar, batteries, PGE, and the generator. This gives you redundancy and optimizes costs by running the generator as little as possible, while sending electricity to the grid only when profitable. This is an area that technology is rapidly evolving, and the latest systems, like Franklin (https://franklinwh.com) support this kind of thing. Such a system looks like this:
Batteries --à| -> Controller -> Main Panel (backed up loads)
Generator -> | -> Sub Panel (non-backed up loads)
If you made it this far, you are probably wondering about the economics of all this. In fact an all-in solar + battery + Generator system will pay for itself for many houses in about 12-13 years and provide a full return on its investment over a 20–25-year period, and you are easily looking at a $90K-100K investment for a full system. To evaluate this, ask yourself will you still be living here in 20-25 years? In the flatlands having a solar system adds to the value of a house; in the mountains the uncertainties over insurance and things probably overshadow this. At the same time, while solar panels have a well understood lifespan, the batteries and controllers are undergoing rapid technological change and will probably be hopelessly obsolete after ten years even if still fairly functional. So this system will work beautifully, but it is complex, and you will have a somewhat marginal return on the investment. You do have to think about this carefully if it really makes economic sense for you.
Summary: For a new install, a system that combines solar, batteries and a generator provide the most reliable possible power, albeit at a significant investment that pays for itself after a relatively long period of time. Technological improvements are likely to reduce the cost of this option over the coming years.
An additional wrinkle is electric cars. As of today, the economics for electric cars are not as clear cut as they might seem. The energy costs of a Tesla Model 3, one of the most efficient electric cars available, are about 2/3 those of a Toyota Prius. While the Tesla is very affordable, many electric vehicles are decidedly more costly than a gasoline vehicle. But… if you have a solar system and have the capacity to charge the car, you get free electricity. The gotcha is, will the car be home during peak sunlight hours to get charged? Admittedly, if you have batteries, you could move the electricity at night too, but keep in mind that especially large electric vehicles (like a truck) have huge batteries that can slurp as much power as your entire home battery, so that’s not necessarily that helpful. But if you are a bit flexible, solar power really improves the ROI of an electric car.
But what happens during a long power outage? You may have enough solar power to run your house, but will you have the power for the car or cars too? And what happens if you are just on PG&E? Well you can charge the car from your generator, but this is absurdly expensive. The better thing to do in this case is charge the car just enough to let you drive down to the valley and go to a public charger to finish the job. If you are really paranoid, you may want to always have at least one gasoline or diesel-powered vehicle on hand, to make sure you can get out no matter what.
On the other hand, the new electric pickup trucks with their huge batteries are capable of providing power to your house. This requires a bidirectional level-2 charger. With a system like the Franklin one described above, your truck can become just another power source. In an emergency, you can provide a significant amount of power for your house from the truck. Clearly you will be limited in duration and amount of power being provided, but it provides another emergency option. This definitely works, and owners of the F150 Lightning have already successfully used the truck mostly in hurricane or other storm related power outages to provide power to their home.