It’s never been easier or more profitable to switch to renewable energy (RE) -- or store power, whether you’re grid-tied or you're your own power grid.
But there’s never been more misinformation, confusion, or marketing hype.
Our engineers and battery specialists created this guide to give you clarity -- and help you avoid the biggest, costliest mistakes in RE battery systems.
Mistake #1: Starting with batteries
If you’re installing or upgrading a renewable energy system, we recommend you lower your energy demands first and then select batteries.
Why? It’s simple: The less energy you need, the fewer solar panels and batteries (and wind turbines) you’ll have to order.
So before you size out your renewable energy system, talk with your battery distributor and installer about improving energy efficiency. It’ll save you lots of money and ensure your building operates more sustainably.
(Be wary of any battery distributor or installer who doesn’t ask questions about your system -- because one-size-fits-all solutions don’t work.)
Here’s how to slash your energy demands -- and operating costs:
- Make sure your thermal envelope is tight. An energy efficiency auditor or your installer can perform a full inspection, including a blower door test and thermal imaging.
- Next, seal and insulate the building -- so you aren’t paying to heat or cool the outdoors. Sealing and insulation can stabilize temperatures and drastically reduce HVAC costs.
- Finally, reduce electrical loads. Consider upgrading to EnergyStar appliances, especially for energy-intensive items like fridges, clothes dryers, and HVAC equipment. And upgrade “low-hanging fruit” like high-efficiency lighting, smart power strips, and low-wattage electronics for a quick payback.
If you’re interested in learning more about improving your energy efficiency, consider these sources:
- Green Building Advisor (https://www.greenbuildingadvisor.com/)
- Musings of An Energy Nerd by Martin Holladay
- The Homeowner’s Guide to Renewable Energy by Dan Chiras
Mistake #2: Undersizing or oversizing battery banks (improper load calculation)
Once you’ve optimized your building and electrical loads, you’re ready to calculate how much power generation and storage you need.
There are three ways to do this:
- Work with a trusted installer or battery expert.
- Use powerful online calculators to perform these calculations yourself.
- Pay 3-4X more for an undersized battery bank from a fly-by-night battery company.
Let’s look at each of these options.
Trusted installers or battery experts make it easy to size your system. They work hand-in-hand with you to ensure you have power reserves for days with low solar or wind generation. And they’ll protect you against buying too much or too little generation and storage. (Note: The sizing process will be easier if your supplier already sized your solar electric system recently.)
You can calculate your energy needs on your own, but it takes extra work and strong attention to detail. (For instance, off-grid users will need to consider when they wash clothes, run the dishwasher, etc. -- details that installers have calculated thousands of times.) If you opt to size your system yourself, consider asking a renewable energy installer or battery distributor to share feedback on your work.
Going the DIY route for sizing? This article by Instructables can help you get started: How to Size Your Off-Grid Solar Batteries (Instructables)
As you’d imagine it’s hard to sell a product for 3X more if you compare apples to apples. That’s why you’ll frequently see some commissioned salespeople push drastically undersized lithium-based battery banks -- to make the price seem less expensive. (You’ll learn how to spot them in Mistake #3.)
But you need a safety margin of reserve power. And with an undersized system, you don’t get it.
For off-grid systems, professional installers generally recommend 3-5 battery days of power -- enough storage for three to five cloudy days. Your needs will vary based on the amount of sunlight (or wind) you get.
And that leads us to the next common mistake...
Mistake #3: Believing “80% Depth of Discharge” claims
Depth of Discharge (DoD) tells you how much of a battery’s energy you can use -- how low it can be drained -- without compromising longevity.
For example, an 80% DoD rating for a lithium-ion battery means that it should be able to be drained until just 20% of its electricity remains.
This is convenient on paper.
But it doesn't work in the real world.
See, in renewable energy systems, you need a safety margin --ample reserve power -- to ensure stable voltage. It’s the only way to power large loads and high-wattage appliances. And it’s the only way to keep the lights on when there’s little sun or wind to harvest.
That’s why installers recommend planning for 50% DoD as a safety margin.
So whatever battery chemistry and company you choose, make sure your system specifies 50% DoD in writing.
Note: Be alert to new, unplanned, or higher than expected electrical loads -- especially if your system has little reserve power. For instance, a new pressure cooker can easily use 1 kW/day. A grown child moving back in can greatly increase TV and other power consumption. And for businesses, new machinery can skyrocket energy demands.
Mistake #4: Selecting the wrong batteries
Now that you know how much battery you need, it’s time to select the right battery chemistry for you.
Crown Battery offers 99% recyclable lead-acid and maintenance-free AGM batteries; the technology has been proven safe and refined over 40-100+ years -- and we’ve reinvented it with computer-aided design and robotic assembly.
But we’re the first to admit that there’s no perfect battery -- only the right battery for your system, your operating conditions and risk level (see link below), your budget, and your habits.
GREENWASHING ALERT: If sustainability is important to you, be sure to find out whether your batteries will recycle (North American Clean Energy).
Mistake #5: Buying a battery with a weak warranty
Ever wonder how brand-new companies can claim ten-year battery life? We have, too.
That’s why we’ve spent more than a decade studying warranty coverage in the field -- including which warranties really protect you, and which ones leave you on the hook.
Here’s some of what you’ll need to know:
- Why the best warranty is when you never have to use
- How to ensure your warranty covers your predicted use
- Beware low max rates for charging and discharging – along with operating temperature limits
- How to maximize battery ROI, service life, and uptime
- Which 5 questions uncover the truth about whether a company will take care of you if you need them
- Why you’ll probably lose your warranty if the company files for bankruptcy (companies in Chapter 11 may not need to honor your claim. Chapter 7 companies have zero obligation to.)
Mistake #6: Not protecting batteries from extreme temperatures
Temperature extremes cripple performance and kill batteries early.
See, batteries run best between 50-85°F (10°-30°C).
Cold temperatures reduce battery capacity -- a ~10% decrease in capacity for every 15°F - 20°F below 80°F.
And common DIY battery storage systems can make things worse. For instance, temperatures in enclosed spaces can exceed 140°F (60°C). That’s why storing batteries in the open air or refrigerators and boxes can harm battery life.
Luckily, there are simple solutions:
- Store batteries in insulated structures protected from the elements.
- Ensure proper ventilation for safety (reduces thermal runaway for lithium-based batteries and allows proper ventilation for regular lead-acid off-gassing).
- Insulate storage spaces to reduce temperature swings and HVAC requirements.
- With an installer, find the best cooling method:
- Passive (Venturi, etc.)
- Active (fans, air conditioning, or nighttime air intake for improved efficiency and reduced load)
Mistake #7: Ignoring maintenance
All batteries require regular maintenance to perform well and last longer -- even AGM and lithium-ion models.
Your battery manual should give you guidelines and recommended maintenance schedules.
These rules of thumb will help:
- Remove electronics, jewelry, and metallic objects before maintenance.
- Always wear protective gear -- safety glasses or goggles, long sleeves, and gloves.
- Inspect cables to ensure they’re intact and tightly connected.
- Clean battery terminals to remove corrosion, oxidation, and rust. (Use a scouring pad or brass brush.)
- For flooded batteries, check water levels to ensure fluid covers your battery plates; this prevents sulfation. If fluid levels are low, add distilled water to cover plates.
When you avoid these common renewable energy battery mistakes, it’s easy to go green -- and keep more money in your pocket. That’s good for everyone.