Legal Disclaimer: Vivek Bhatia is not a trained solar technician. He is documenting his experience with Tesla panels, Telsa Powerwalls, and his highly positive experience during a 2 day blackout in Oct-2019. All items on this page are his personal opinion. There are many different "right" answers. If your answer is different but works for you, that's all that matters.

Questions answered below:

YouTube video links that I made:

space left blank in case more questions or videos added, so i don't have to redo the anchor links on this page

Why did I get solar?

99% of people get solar to lower energy bills. Not me. Living in Northern California, we know it's only a matter of time until an earthquake hits. I wanted to ensure uninterrupted access to power without standing in line for hours at a gas station to power a generator. Plus those things require regular maintenance and are loud!

Why did I pick Tesla?

Branding & reputation. This was in 2017, and at the time the smaller companies did solar installs and probably cheaper. I had faith that Tesla would be here in 3 years, I didn't have the same confidence in other companies without a similar track record.

How much does it cost?

It depends on the size of the system and the tax rebates at the time. I'll tell you about my cost in 2017, but it may be very different now. I have a 1650 sqft home but I have a lot of random electronic or electric equipment. I opted for a 7 kilowatt system that could provide most of the power. In Q4-2017 the net cost was $26K after rebate. With a 10 year loan the cost was close to my PG&E bills, but the panels have a 20 year life span so it's effectively half the price.

What determines if I get power from solar or the grid?

You'll have a device installed that determines A) if the grid is up, and B) if solar is providing enough power. Furthermore, at least with Tesla, if the grid is up and you have a bettery, you can set determine how much of your battery to keep in reserve before switching to the grid. on how you set up your powerwall. I have mine set up to first tap into the battery, then when it's at/below 15% to switch to the grid. ​Here's some  visuals from my powerwall, which are viewable on my phone.

 
 
 
 
 
 
 
 
 
 
 
Do I really need a battery?

Personal decision, but for me the extra $7500 for a powerwall (in 2017) was well worth it for the following reasons:

  1. Avoid Long Lines

    • Grocery stores may be closed and/or have long lines to purchase ice to keep milk for young kids or medicine cold. And it could melt by the time I get home.

  2. Eat something other than dried or preserved food

    • Quickly eating any refrigerated food may not be possible, and I'd need to resort to eating granola, bars, or freeze dried food.

  3. Heat

    • We have a gas furnace but it needs electricity for the thermostat.

  4. Preserve Cash

    • Credit card machines likely will not be working, so I'd have to spend precious emergency cash.

How much big of a battery do I need / how long does it last?

Not a one-size-fits-all answer. It depends on how much you power. I was able to run a refrigerator, a few lights, on ~7 kilowatt hours/day.  Your fridge will be a different size & efficiency, and you'll have a different number and type of lights.  Your solar system will recharge the battery during the day, but if this happens during the winter or it's rainy it may only generate a few kilowatt hours. I'd recommend getting at least 1.5 times your daily consumption as a hedge against bad weather. If the weather is bad, you can always shut down everything except the fridge to stretch out your battery. 

How do I measure how much energy my house needs on a daily basis?

First, write down everything you'd want powered in the event of an outage. Then, buy an electricity usage monitor like the Kill-A-Watt, they're $20-$30 on Amazon . If your items are plug-in devices like a refrigerator or a medical device, you plug it into the kill-a-watt, and plug that into the wall. Let it run for at least 24 hours, ideally 3-7 days so you can get a good sample set. Items like fridges have cooling cycles that vary based on human behavior such as how often you open it. Letting it run for multiple days gives you a nice average. Write down the daily average in watts and move on to the next item. For lights that are directly connected to your panel look at the bulb you use. If it's a 5 watt LED, then running it for 24 hours=24*5. Obviously you won't run those lights all the time. Be careful of kitchen or dining room fixtures with many bulbs, turns out our very pretty kitchen light fixture burns 300 watts per hour, which is more than my fridge! 

What's the best way to reduce energy consumption during a blackout?
  1. Power Strips. Remember that all electronic devices such as TVs, stereos, Amazon Echo, Sonos, and even laptop chargers use a little bit of energy at all times. This is how they power on so quickly. Buy at least 1 cheap power strip for every room *before* a power outage hits and plug everything into that. The second you notice the power is out turn off every strip. That way you won't bleed any energy to devices that you won't think of using. I decided to buy two power strips for bedrooms & the ktichen: 1 for "items to turn off until the power comes back" such as TVs, and 1 for "items that can be powered if the battery has sufficient power", such as a 2nd light or an iPad charger.

  2. Stick with candles & candle lanterns. Unless the weather is predicted to be sunny for days or there is some estimate of when power will return, keep using candles & candle lanterns as one of your primary light sources. 

How exactly does it all fit together?

Easier done via a video. Click here for a YouTube video I shot on May 21, 2018, when I first turned on my system. It'll walk you through the whole thing.

Okay, I have solar. Is there anything else I need to do?

Buy power strips as per the above answer on reducing energy consumption.   

How should I change what's in my earthquake kit now that I have solar?

Don't change anything. The earthquake is severe enough to damage your solar panels. 

What was your experience during the 48 hour blackout in October 2019 power outage?

It was incredibly positive. The powerwall took over within milliseconds, I wouldn't have even known the power was out if Comcast hasn't dropped. I thought it was just another outage when I realized it was incredibly quiet and dark outside.  And, the solar panels continued to charge the powerwall despite the grid being down.

I have 2 power strips in each room: One with items to immediately turn off (TVs, stereos, etc), one with low-power items I'd be willing to enable if we had enough energy (alarm clocks, 1 LED light, cell phones). I rapidly ran around the house and turned off both strips in each room. I left only the fridge powered on, then used the powerwall UI to determine how much power was stored vs being drawn. Once I realized we had plenty of power, I turned on the power strips to the low power items. Here's my favorite picture: By 10am we were producing 1 kW of power, more than enough to power the toaster and lights, and still send power to the battery. 

 

 

 

After we all had some toasted bagels I stayed super-conservative in our consumption until 24 hours had passed and I knew what we were consuming, and if the solar panels would truly work. They did, although on one day they had fully charged the powerwall by 12pm and the system discarded nearly 11 kWh of production capacity as it couldn't be sent to the grid like it normally does when that occurs. Here's a comparison of Saturday (no blackout) and Sunday (grid down).

If you have any questions or want me to ad something to this, either email me or post a comment below. Thanks for reading.

 
 
 
 
 
 
 
 
 
 

PG&E power grid running

PG&E power grid down (blackout)