Home Battery Systems

Home Battery Systems 101

Though people have been living ‘off-grid’ for many years, most of those systems provided a lifestyle that is closer to camping;  powering some dim lights and a small fridge. The batteries had to be replaced often and were easily damaged.  However, with our high powered Lithium batteries you can store enough power to have run your home seamlessly.  They have virtually no maintenance, a 10 year guaranteed with life expectancy of 20+ years, at a price that is affordable for the average homeowner.  A home battery system will pay for itself, save you money, and you’ll never experience a blackout again.

How a Home Battery System Benefits You
     ~ Store Free Solar Power during the day--Use it to Power Your Home During 'Peak Rates' and at night
      ~ Pays for itself, by saving money on your electric bill
      ~ Backup Power gives you true energy independence
     ~  Never experience a power outage again - even during California's Public Safety Power Shutdowns

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​Use Solar Power during evening 'PEAK RATES'

The major utility companies in California now charge all their customers about double for power during the evening from approximately 3pm to 9pm (depending on your utility company and rate plan).  That's because it's the time you are most active in your home!  So just when you want to turn on the lights, run the air conditioner, make dinner, do some laundry, or other things that use electricity, the power company is gouging you.
But with solar and a home battery system, you can fight the power company and take control of your electricity costs.  By making free solar power during the day and storing it in a home battery system, you can power your home during those peak times using ‘Free Power from the Sun’.  
 

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LG ELECTRONICS

LG is a name you know and trust, and offers a cost-effective home battery system if you are installing a new solar system,  or already have one using SolarEdge inverters.  It has 9.8kWH and can produce 3,300watts of power continuously. You can couple two or more inverters and batteries together to scale up to a huge amount of power.

 

TESLA POWERWALL2

The most well known home battery.  These are 'AC Coupled' meaning that they have an integrated inverter with AC power output.  If you have a solar PV system already or don't even have solar panels, this is the best solution for you, as it operates totally independent of any solar installation. It has 13.5kWH of usable energy and can deliver 5,000watts of continuous power.  You can couple up to 9 batteries, for a whopping amount of power that will keep the air conditioners running and anything else you want.

 

GENERAC PWRCELL

This is our most robust and efficient system, from the company that invented backup power systems over 60 years ago.  The PwrCell is modular, with a box that comes with 3 battery packs totalling 8.6kWH of storage. You can add up to 3 more battery packs 17.1kWH of storage.  Also, you can couple two PwrCells together for double that power, for a system capable of powering most any large home.  If you want to keep an air conditioner powered during an outage, Generac is your product. ​

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AC Coupled vs. DC Coupled
You lose a bit of efficiency in the system every time you have an AC to DC or DC to AC conversion.  AC to DC is called a 'conversion', and DC to AC is called an 'inversion'.  The fewer times you make that inversion/conversion, the more efficient your system will be. 
   

With an AC Coupled system (Tesla Powerwall2) the solar panels make DC power, which is then inverted to AC for your home.  The Powerwall charges itself using your home's power (either solar or from the grid) with AC and then converts it to DC to store in the battery.  Then it inverts it back to AC for use in your home when you need it.  That's three inversion/conversions.  So though it is very convenient to have a totally autonomous battery system, it is less efficient, and requires a dedicated circuit adding a bit to the complexity of the installation. 
 

With a DC Coupled system (Q Cell, LG Chem, Generac), you only make one inversion.  The solar panels make DC power.  The SolarEdge, Q Cell,  or Generac device takes that power and provides electricity for your home, and any excess solar power stays DC and charges the battery directly.  Then when you need power (like at night or during grid failure), the inverter takes the power from the battery, inverts it to AC, and powers your home.  There is only one inversion, and results in a significant improvement in efficiency.  Also, it uses one circuit for the solar/battery system so its easier to install.

What to Expect when considering a Home Battery System

CAN I REDUCE HOW MUCH SOLAR I NEED WITH A BATTERY?
NO!  At least not reliably.  We hear this one all the time.  People we consult with for home batteries tell us 'the other guy' told them that they could install fewer solar panels if they install a home battery.  If you hear someone tell you this, they simply don't understand how battery systems work.  

Its very simple - solar panels MAKE electricity from the sun, a home battery STORES  the electricity.  You need a certain amount of electricity to run your home, and that electricity needs to be made somehow - whether by solar on your home or a power plant located far away.  Think of it like your car:  gas is like power, and your gas tank is like a battery.  Your gas tank doesn't make gas, it just stores it.  But you have to put gas in your gas tank to have the power to run your car.  You have to put power into your battery tank for it to power your home, and that power must come from solar or the grid.

You might be able to save a bit of money (not panels) by 'arbitraging' the peak rate, which means you store free solar power during the day, then during the expensive 'peak rate' from the utility (approx. 3pm - 9pm, depending on your rate plan) you power your home with a battery, saving money.  Yes that works, but it requires you to be very disciplined on your electrical usage during the evening (when you use most of your electricity) and also presumes the utility won't change the rules.  If you wish to arbitrage the peak rates, we are happy to set your battery to the correct setting, and show you how to maximize your savings.  But we believe that solar is supposed to provide freedom from the utility company, not become even more of a slave to it every single evening.  Install enough solar to offset 100% of your usage, and then relax knowing you'll never pay for power again.

 

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CAN I QUIT THE POWER COMPANY?
The answer to this question isn't so cut and dry. On a normal day with solar and batteries, you won't be using the grid at all, but instead be 100% energy independent. But we want to be very clear here--We DO NOT recommend that you disconnect from the grid. It is a reliable backup for those days when you need more power, like when it's cloudy, in winter when the days are short, or when you use more power than normal. We actually do have several customers who are completely off-grid. But to be truly off-grid and not worry about running out of power, you need to build a solar and battery storage system large enough for worst-case scenarios, like a week of rainy days or the increased power needs if you have guests stay for extended times.  The general rule to be off-grid is to build a solar and battery system that is twice the size you need for normal days, so you'll spend double the money - we don't want that.  Instead we recommend a system that will power your home for a normal 24hr day, and then keep the grid connected in case you need it. 

WHAT CAN I POWER WITH A HOME BATTERY SYSTEM?
In most cases, we design a home battery system to power your most important electrical circuits.  Typically,  we install a Backup Loads Breaker Panel so that if the grid fails, you can power your refrigerator(s), two light circuits, the TV, Cable Box, WIFI and modem, the house alarm, the garage door opener, and a plug circuit or two so you can run a fan, charge your phones and run a computer.  This provides the best bang for your buck, has a lower cost, and gives you a comfortable life while you are waiting for the grid to turn back on, or the sun to rise the next morning so you can power your home with solar. 

​CAN I RUN ALL MY LOADS ON THE BATTERY?
Yes – kind of.  Air conditioners, laundry appliances, and pool equipment take a loto of power, and it takes a very robust battery system with multiple batteries to power those.  The Tesla Powewall provides 5,000 watts, the LG Home Battery provides up to 3,700 watts,  and the Generac PwrCell up to 6,700 continuous watts of power.  This will provide more than enough power to take care of the most important electrical items all through the night, until the sun comes up and your solar takes over.  However, If you wish to run appliances that total more than 6,000 watts, you'll need additional batteries.

HOW LONG WILL THE BATTERY POWER MY HOME?
That will depend on how much power you use.  A typical home has about 600watts that are always on, like the fridge, cable box and modem, and all those little items that have a box on the electrical chord (called a power supply).   If you add a few lights and fans, charge phones, and have a few other items plugged in,  you’ll be at 750watts.  The rest is simple math. Add up your usage, multiply that times the number of night hours, and you'll know how many hours your battery will last.  If you use 750watts, multiply that times a summer night of 10 hours and you'll need 7500 watt-hours or 7.5kWH of storage.  Our LG Home Battery has 9,800 watt-hours of power storage, so it will get you through most nights from spring through fall.  But in winter, because nights are longer and the days are shorter (so there is less time for solar to generate power) you may be needing the grid to help you through the night.  If you don’t want to use the grid at all, you either have to lower your consumption, or buy a second battery.  In that same scenario, a Generac PwrCell with 4 battery modules or the Tesla Powerwall2 with 13500watt-hours will have ample power.

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WHAT IS THE COST, AND ARE THERE REBATES FOR A BATTERY SYSTEM?
The cost depends on the size of your system, what your goals are, if you are installing it at the same time as a solar system, and more.  Because whole home battery systems with lithium batteries are fairly new and the prices to us change almost weekly, we can’t quote them here on the website.  But be thinking about $12,000 for our Q Cell system installed at the same time as a solar panel system, which includes permitting, backup loads panel, inverters, automatic transfer switches, battery, labor, and more. 
There are rebates for these battery systems.  The Self-Generation Incentive Program (SGIP) can give you a rebate of several thousand dollars.  There is also a 26% tax credit for home battery systems.  With the rebates and tax credit, you'll enjoy about 50% of your home battery system paid for with incentives.

SGIP REBATE: Free Money, but with Strings Attached.
Regarding the SGIP rebate – it’s a significant amount of money, however there are strings attached from the state of California.  Since they are paying for part of your battery, they can take the power out of your battery when they need to.  Also, you must discharge your battery completely periodically.  If the utility company depletes your battery and coincidentally there is a blackout before your battery is re-charged, your home will be without power like everyone else. To us, that defeats the purpose of having a battery!  About 80% of our customers opt out of getting the rebate,  but we are happy to apply for the SGIP rebate if you wish. 

FREE HOME BATTERIES - the SGIP Equity Resiliency Program: 

There is a new program beginning April 2020 that will pay for almost 100% of your home battery system called the Equity Resiliency Program.  Nearly everyone that lives in the hills or mountains qualifies, and here's how:  You must a) live in a stage 2 or 3 fire zone, OR have had two or more Public Safety Power Shutdown (when the power company shuts down the power to prevent fires); and b) live with well water, OR be eligible for the Medical Baseline rate from the power company, OR have a medical device that requires electricity and notify the power company of it.  This rebate is $1.00 per watt-hour.  The Tesla Powerwall is 13,500 watt-hours of usable power, so the rebate is about $13,500!  And you can get two or three if you want.  It's an amazing program.

​ If a home battery system sounds like a good solution for you, give us a call. 
We will bring the best the solar and battery industry have to offer, and help you
achieve your goal of total energy independence.