GreenWattWise Lab
Smarter Decisions for a Brighter Tomorrow
Clear. Practical. Unbiased guidance on home batteries, solar and energy independence.
Independent home-energy guidance
Understand the numbers before you buy.
GreenWattWise Lab helps homeowners make smarter home-energy decisions with independent guides, practical calculations, and clear comparisons.
We start with one of the biggest questions in residential energy: what size home battery do you actually need?
Home energy (example)
- Daily use
- 18 kWh/day
- Solar
- 6 kWp
- Night use
- 8 kWh
Suggested battery range
7–10 kWh
Illustrative example only — not a sizing recommendation.
Independent
Guidance designed around homeowner decisions — not a particular battery manufacturer.
Practical
Understand the numbers that matter before comparing systems and installer quotes.
Clear
Engineering concepts translated into useful explanations for non-engineers.
A battery quote gives you a number. That doesn't mean it's the right number for your home.
Home batteries are commonly offered in capacities such as 5 kWh, 7.5 kWh, 10 kWh, 13.5 kWh, 15+ kWh. But battery size should be connected to how your home actually uses energy, what your solar system produces, and what you expect the battery to do.
GreenWattWise Lab helps you understand those relationships before you commit to a system.
Start with the question you're trying to answer.
What Size Battery Do I Need?
Learn how household consumption, nighttime demand, solar production, and backup goals influence battery capacity.
Start the Sizing GuideCompare Battery Sizes
Understand what changes when comparing common home battery capacities — and why bigger is not automatically better.
Explore ComparisonsEvaluate a Battery Quote
Learn which numbers and assumptions matter before accepting an installer recommendation.
Explore Home Battery GuidesFeatured guide
What Size Home Battery Do I Need?
What Size Home Battery Do I Need?
A practical introduction to sizing a residential battery using the energy your home consumes, when you consume it, your solar generation, and what you want the battery to achieve.
Read the Battery Sizing GuideA better battery decision starts with the right questions.
Understand your energy use
Start with how much electricity your home uses and when that consumption occurs.
Define the battery's job
Solar self-consumption, backup power, tariff optimization, and other goals can lead to different sizing decisions.
Compare usable capacity
Battery nameplate capacity is not always the same as the energy available for everyday use.
Evaluate the trade-offs
More battery capacity can provide more stored energy, but additional capacity only makes sense when your energy use and objectives can justify it.
Ready to go beyond the estimate?
Home Battery Buyer Toolkit
The complete GreenWattWiseLab system for understanding battery sizing, working through the numbers and approaching installer quotes with more confidence.
- The Essential Edition guide
- The Home Battery Decision Calculator
- The 91-page Complete Guide
- A printable installer checklist
Complete buying system
Includes the Essential Edition, the Battery Decision Calculator and the additional buyer resources included in the Toolkit.
Explore the Home Battery Buyer ToolkitIndependent, manufacturer-neutral battery guidance.
Or start with:
Just learning?
Understand the battery numbers that matter, common sizing mistakes and the questions worth asking before you buy.
Only need the calculation tool?
Explore your own household and battery scenarios and test how different assumptions affect the decision.
Watch & Learn
Prefer a visual explanation? GreenWattWise Lab also breaks down common home-battery questions through short educational videos.
Your Installer Quoted a 10 kWh Battery — Do You Actually Need It?
A practical look at why a quoted battery capacity should be connected to your home's actual energy needs.
What Size Home Battery Do You Need?
Understand the main household and energy-use factors that influence residential battery sizing.