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.
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:
If you’re interested in learning more about improving your energy efficiency, consider these sources:
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:
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)
Finally, beware companies that undersize batteries. Some battery technologies cost 3-4X more than lead-acid for the same capacity.
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...
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.
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.
Want a quick crash course in battery technologies? Click here to see North American Clean Energy’s article Find the Battery You Need.
GREENWASHING ALERT: If sustainability is important to you, be sure to find out whether your batteries will recycle (North American Clean Energy).
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.
The full story is in North American Clean Energy’s Nov./Dec. 2020 issue (page 26).
Here’s some of what you’ll need to know:
Will your next battery warranty protect you? Click here to discover what to look for (SEE PAGE 26).
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.
Meanwhile, high temperatures increase corrosion and fluid evaporation (result: damaged grids). In fact, every 15°F average operating temperature above 77°F slashes battery lifespan by half.
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:
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:
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.