Adding Powerwall Batteries to Existing Solar

Earlier this year, Tesla stopped selling Powerwall batteries standalone... they currently only sell them to new solar customers.

We wanted to add storage to our home but we already have solar, so this was really disappointing to hear.

On a whim, I called SunPower, the company that installed our solar panels, and they told me that resellers/installers like them DO have access to batteries. So we were able to order our Powerwall batteries last month!

It's not all good news... the current estimate is 12-18 months(!) until they arrive. But at least it's in progress! More on our battery learnings in future posts.

Upgrading to 100% Renewable Grid Energy

One super easy change we made to get greener was transitioning to a renewable energy provider, in our case East Bay Community Energy. We did the same when we lived in NYC and we bought energy from Green Mountain Energy.

Changing energy providers away from the well-known and (relatively) trusted PG&E sounds scary. Why would you trust all the power in your home to a community provider that you've never heard of? That's what I thought, but it's not like that at all.

You see, PG&E is still delivers our energy. They repairs issues and send us our invoice. But the underlying electricity is provided by a 3rd party who purchases100% renewable energy from wind and solar. 

Making this change is WAY easier than it sounds to. You fill out a web form. There is no step 2.

In the form, I could choose 100% renewable for slightly more money, or a mix for slightly less. We went with the former. It's unfortunate that getting energy from EBCE (or similar community provider) is more expensive than  getting directly from PG&E. Having to pay a premium to switch to renewables -- with no change in lifestyle or performance -- is a shame, and hopefully this will change over time and come down in price. 

The be clear, the actual difference in our utility bill is completely negligible - literally pennies different (after our rooftop solar). But it's a bummer when trying to convince others to make the change. It's WAY easier to convince someone when the pitch it "and it's cheaper" or "and you'll have no change in price" and not "well... um... technically it's more expensive."

But this is such an easy change for anyone to make -- there's no reason not to make this change yourself today.

Sizing Our Solar Panels

We got solar panels last year. This was before we were on the whole #ElectrifyEverything kick, but we felt some time pressure:

• Tax Credit: We wanted to lock in the 26% tax credit before it decreased. The credit has since been extended, but we didn't know that at the time
• Lock in Utility Rate: Our utility, PG&E, was looking to make pricing changes, most notably around connectivity fees ($10 => ~$60), time-of-use rates (more expensive in the evenings), and the price they purchase excess solar back (it's dropping). We wanted to lock in the current rates/policies (Net Metering 2.0) for 15 years, which meant installing our system before Net Metering 3.0 gets passed. (as of this writing, the new regulations are still being decided. If you live in CA, call Gov Newsom and urge him to keep solar affordable)

That's the boring part. The more interesting part was how to size our solar panels AKA how many panels to get. (a note on sizing things being "the more interesting part": I personal like combinatorial optimization like the fixed-size knapsack problems. YMMV)

We went with SunPower (a very reputable CA solar installer. hit me up if you want an introduction). Our sales rep looked at our existing utility bills to help us size our system. The problem is, our life is almost entirely natural gas, so historical data was unhelpful.

Rather, we had to size our system based on probability that we would switch to electric, and when. 

There's a vast difference in the number of panels needed for our life today, and our future with 2 EVs, an electric jacuzzi heater, and more. But we didn't know when we would be switching everything over... it could be 10 years! So our payoff calculations change drastically if we oversize now but don't use it, or undersize now but transition to electric quickly. Upgrading later is possible, but without the same tax credits and paying for labor twice. Oh, and there are different manufacturers and photovoltaic density on panels, each with different costs. Another variable.

Aurora Solar, one of the really cool tools that installers use to estimate projects, just doesn't handle this much ambiguity from a customer. 

I quickly realized this was going to lead to an overconstrained series of equations, so I got all the ratings, metrics, and costs and plugged it into Google Sheets. 

In the end, we sized for 2 EVs and a hot tub. This was definitely overkill for 2021 but will likely serve us will in 2022 and 2023. It's likely too small for an all electric future, so we may want to revisit later as we upgrade appliances too. (Note: utilities buy power back at pennies on the dollar. It's not like you make a profit there. So an over-sized system is generally just wasteful)

Oh, and one interesting hack we found... newer panels are denser, which gives more energy per square foot. We have a very large roof, so the number of panels wasn't a concern for us. Turns out we could purchase more of the older, less dense panels for less money than fewer high density ones. It takes up more space on the roof, but we have plenty of room, so that seemed like a nice money saving trick. 

Conclusion: this stuff is remarkably hard to get right! Maybe I was overthinking some of this by trying to optimize carbon footprint with economic payback time, but sizing a system and laying out tens of thousands of dollars (or signing a financing contract) BEFORE you've electrified everything and your electricity bill is small (like ours today) is a tough leap of faith to make.

Our Service Upgrade: Municipal Utility Code and Zoning Regulations

Who clicks a link with that title? Seriously. That's literally the exact OPPOSITE of clickbait. 

We live in Oakland, CA and according to code, an electric meter (or main panel? or both? not sure) can't be within 3 feet of the gas meter. 

Our house was built before that regulation, so the meter is just 2 feet away. The electric meter is the box/circle right in the center, and the gas meter is the gray contraption in the lower right, next to the flower pot.

Replacing the 100A main panel with a 200A main will require moving the panel left so we can pass inspection. The astute observer will notice there isn't actually any enough additional space to slide the panel over!

The only option we currently envision is moving the panel left around to the FRONT of the house. There is probably enough clearance to put a meter here:

If that's do-able, then fine, that's our path forward. But a few questions and concerns here:

1. Can an electrical meter be that close to a window? One electrician said no, another said yes as long as it doesn't open (which it doesn't). So fingers crossed on this one.
2. Is there enough width? We measured and I think so, but it's gonna be close
3. Will Oakland zoning allow us put a meter on the front of the house? We contacted the city. This is allowed as long as it's obscured by landscaping or similar. So it's probably fine. 
4. Isn't it ugly to have a meter on the front of the house? Yup. Plus all the conduit running 200A wires. Ugh. We'll likely plant in front of it, so it shouldn't be too bad. Alternatively, if we get a Span meter, it's really well designed -- white and sexy -- which you can argue makes our house look a forward-thinking progressive home. I'll probably lean into that :-)
5. Isn't it going to cost more? Absolutely! That's the theme of this project, and should probably be the name of this blog. 

PS This post an example of this blog getting into our super specific circumstances. But I imagine everyone will have something like this.

Phase 1: Service Upgrade

Most homes are currently wired with 100A coming to the house and connecting into a 100A main panel. Historically this is plenty for most homes that use natural gas, but not enough to simultaneously power everything if it's all electric. There simply isn't enough capacity to, say, charge 2 cars, dry clothes, and cook at the same time. 

There are a few solutions to this:

• Change behavior to not charge cars, dry clothes, and cook at the same time. While this is do-able, we're never going to convince millions of households to voluntarily electrify if they have to change behavior. We need to make the clean future MORE attractive, not less.
• Upgrade service to 200A. This involves an electrician, city inspection, and utility inspection. Plus buying and installing an upgraded main panel designed for the increased load
• Get a load shifting smart panel. New products on the market like Span can automatically and dynamically adjust loads to keep your system functioning. Have spare capacity? Charge the car faster. Need to wash clothes? Stop charging the car. 

These aren't mutually exclusive. For example, we probably will want both a service upgrade and a smart panel. 

The service upgrade is one of our first priorities. We don't want to be in a situation in the future where, say, our hot water tank breaks, but we can't switch to electric because our house can't handle the increased load. And since it can take weeks or months to get a service upgrade (city inspection, utility inspection, and actually finding an electrician who can start work), which is too long to go without hot water. 

Oh, and the service upgrade is sorta forcing our hand to decide on a smart panel now. We likely don't want to buy an upgraded panel now, only to replace it with a Span down the road -- that's just wasteful. And we'll also want our (eventual) storage batteries connected to the smart panel. No sense hardwiring them up to our critical loads, only to rewire it to a smart panel later. So this adds more moving parts to Phase 1, but it's probably the better plan.

PS a smart panel and a smart meter are different. Most modern homes have smart meters... they send your usage data back to the utility without a human coming out to read the meter. Quite common and you'd never know it. Smart panels are very new innovations. Your circuit breaker goes inside the smart panel, automatically controls where power is flowing in your house, and gives you a pretty mobile app to control it all.

Starting our Journey to Electrify Everything

Our New Years resolution is to electrify everything in our home and transportation. We want to be on 100% renewable energy by 2025*.

Our current (pun intended) situation, like most folks, is about as far from that as possible:

Our house uses gas heat, gas hot water, gas stove, gas washer/dryer, and a gas fireplace. And we drive 2 gas cars.

To add to the complexity, we are also planning an outdoor renovation in 2022. The original designs included a gas fire pit, a gas grill, and a hot tub, so we'll be revisiting those decision too.

We are now a few months into the process and I am shocked (i love puns so much) at the cost & complexity of it all. It's also hard to find reliable information. And we're coming into this highly motivated, informed, and able to afford the current (i love puns) upfront costs. So if it's hard for us, we're never going to get 100 million homes converted in time. So I decided to write it our experience as we go. I'd expect large swaths of it to be boring, and other parts to be unique to our specific situation. But maybe there will be some useful nuggets of wisdom in there. Or at least some puns.

PS This blog (probably) won't go into all the details of why we MUST to clean up the power grid and why electrifying everything with renewable energy is our inevitable future. You can read books by better writers than me: Electrify by Saul Griffith or Speed and Scale by John Doerr are quite accessible. Or if you're more of a podcast person, here's an interview with Saul on Vox. 

Onward and upward!

* 2025 is arbitrary. We want to be really aggressive with our timeline, but we also don't want to throw relatively new and working appliances into a landfill. So it could be sooner or later. The tradeoff between committed emissions (how much our existing fossil fuel machines will continue to pollute) vs trashing appliances before their end-of-life is one example of a really hard question we're facing. Do we drive our gas car into the ground? Or trade it in ASAP? What about a stove? Hot water heater? When is the "best" time to upgrade appliances, environmentally speaking?