A lot of people have asked my why I have no batteries to go with my solar array. Here is the reasonings
I did touch on these slightly in my power monitoring post, and my power FAQ, which can be read below
But here is the full answer. For someone who uses a lot of power and lives in a hot, humid area like Houston, I don't think they make much sense right now.
There are three reasons I can see for why you would want a battery, and why I don't really see them working for me.
Store Excess Solar for later use
If you live in California or Hawaii or any other state with utilities/governments that are hostile to Solar, you probably have a lot more incentive to get a battery. Here in Texas at the time of writing, we get 1:1 net metering. That means I sell excess power back to the grid at the same price that it costs me to buy power.
So if I make 40kwh extra in the middle of the day, I can then just pull from the grid at night to use that extra power, and it costs me nothing. So for right now, there is absolutely zero incentive to get a battery for that purpose.
Of course if they end net metering, getting batteries starts to make more sense.
Protect Against Short Outages
If you get batteries and have a short outage, everything in your home will stay powered. For me this is not really a concern, as ALL of my important equipment is already on a UPS, and always will. So I see no value there.
Protect Against Long Term Outages / Grid Independence
This is one of the main selling points for battery systems, but for us Texans using their AC all the time, it just doesn't work. Here is an easy to read screenshot showing this problem
This day was hot and humid and so I had the AC on during the day. As you can see, I made a TINY amount of solar. I have 45 Solar panels covering the majority of my roof, with just space left for maybe 6 more panels at most.
If we pretend the power was out during this day, I would need AT LEAST 4 of the new 13.5kwh Tesla Power Walls. Assuming the current 26% federal tax credit, and the quantity of 4, it would cost me around $30,000 according to quotes I've gotten. This is $10,000 more than my very expensive liquid cooled generator.
Now the problem is, that $30,000 install in this case would get me just 1 day of backup power assuming the next day was cloudy too. I don't know about you, but I don't want to spend $30,000 and possibly only get a single day of backup power.
You may as this is an unlikely scenario, but it was a very real situation when Texas had its deep freeze in February 2021.
Then pair that with the knowledge (Correct me if I'm wrong) that the battery cannot self-start and activate the solar panels again, unless there is grid power. So once it turns off after that one day, you're at the mercy of the power grid even if it get super sunny.
Now you are back in the situation of watching the CenterPoint Outage Map, and ERCOT dashboard crossing your fingers hoping the power doesn't go out.
With my generator, it does not matter. I know that I will have power, no matter how much I use. I want to leave the AC set to 68 all day and all night? fine. Want to charge an EV? Fine. There is no worrying about the power going out.
Other Reasons and Thoughts
To be clear, I really WANT batteries because I think they are very cool. But buying one now makes no sense. Here are some other thoughts
Some battery systems with LiFePO4 cells do not have this issue, but they are all much lower capacity and have much lower power output. The Tesla PowerWalls do not use LiFePO4 and therefore will not have as long of a lifetime. Their warranty is 10 years, and they say you should have 70% capacity in that time. Well, my Generator has no real time based expiration, as long as you maintain it, it should last a VERY long time, and it will always have 100% capacity.
Yes, you could DIY a system with LiFePO4 cells and a bunch of capacity, but that leads me to the next point
I don't really want to DIY a battery storage system. I don't have a big open space to mess with it like Will Prowse and its just not something I really feel comftorble with unless I do a TON of research.
Check out Wills channel, its very good
I think batteries are very cool. And the problem is that if I buy the current batteries which I feel are not really any good, I'm then stuck with them while much better products come out. If I wait, I can then choose a much better solution when one finally comes out.
No Generator Integration
So far there is no compelling option to integrate batteries with a generator. I am waiting for a solution where it can link up to my generator, and in the event there is not enough sun, or I need to use power above the limits of the battery, it can spin up the generator and run it at optimal load. Enphase sort of has this, but its heavily limited. It limits the power output of the generator to just 12kw, it limits your main panel to just 150a and is very expensive, and has a limited generator support list.
One day I hope there to be a universal controller you could hook any brand of solar panels into, any brand of batteries and any brand of generators, including portable generators and customize the configuration based on your needs. Right now I don't think that exists.
Waiting for EV Reverse Charging
This is a big one. Why buy a huge battery for your home when we will all end up having at least one EV? A Ford Lightning will apparently have a 130kwh battery. That's almost 10 Tesla Power Walls, and it comes with a free truck...
I can foresee a future where we have just a very small battery on our homes which has very great power output, and can keep the power on while we are out, as then as soon as we get home, it taps into the vehicle battery. I'd then love to be able to utilize my backup generator in this situation too, have it charge up the large battery during the day, and let me run silently during the night on the vehicles battery.
Power Output Limitations
Some of the batteries out there now have PITIFUL power outputs. My generator can output 25kw. An Enphase IQ10 battery which is LiFePO4 is limited to just 3.8kw... That is pretty terrible.
This means that you almost certainly are going to have a "Critical loads panel" where they split off your "critical" devices to get battery power, and the rest will not. In my opinion this is not needed, however all of the companies I spoke to said this is how they will install them, and it will not pass inspection otherwise.
ALL of my loads are critical when I'm spending over $30,000, and I have no issues managing loads myself. Add the fact that my electrical panel configuration does not lend itself to this, and its just not feasible.
Space and Environmental
Putting batteries in the direct sun is a bad idea. The back of my house faces South which is fantastic for solar, but it means the majority of spare space I have is also in the sun. I can only think of a few places where batteries could be easily installed, and they mostly require 100+ ft of wiring, which gets expensive fast, especially at current costs of Aluminum and Copper.
Not any Incentives in TX
There is some really cool projects in other states where you can use, and get PAID to use your battery at home to help power the grid. More here in this video from Matt Ferrell.
If I could do that and get incentives to do it, I think I would probably end up getting batteries just because I think its very cool.
I think that covers all the points I have, if I am wrong about anything please feel free to contact me and I will correct it.
Thanks for reading