Solar & Energy
Guides for Illinois
Plain-language guides on solar, heat pumps, battery storage, windows, siding, geothermal, and every Illinois energy incentive available in 2026. Written by the SPM team.
Start Here
Why Energy Efficiency Should Come Before Solar
Installing solar on an inefficient home means paying to generate electricity you're already wasting. Here's why fixing energy waste first leads to a better system — and a better investment.
Solar Panels in the Midwest: What Illinois Homeowners Should Know
Illinois isn't Arizona, but it has enough sun to make solar a solid investment. Here's what homeowners should realistically expect from solar panels in the Midwest — including winter performance and Illinois-specific programs.
Commercial Solar for Small Businesses: What Owners Should Know
Commercial solar is a different calculation than residential. This guide walks small business owners through how commercial solar is sized, what the tax landscape looks like, and when it makes sense to move forward.
All Articles
How a Home Energy Audit Helps Right-Size Your Solar System
A professional energy audit identifies your home's biggest efficiency gaps. When that data drives your solar proposal, you get a smaller, more accurate system — not a bloated one.
Why a Bigger Solar System Isn't Always Better
Solar companies often size systems around your current — often inflated — energy use. More panels means a larger sale for them. Here's how to think about what size actually makes sense for your home.
How New Windows Reduce Your Home's Energy Load
In Illinois's cold winters, old windows can be your home's biggest source of heat loss. Replacing them lowers your heating load, reduces your HVAC runtime, and — if you're planning solar — shrinks the system size you need.
How Siding and Insulation Affect Solar System Size
Every watt your home wastes through uninsulated walls is a watt your solar system has to generate. Insulated siding and better wall insulation reduce that load — which means a smaller, less expensive solar system.
How to Compare Solar Quotes Without Getting Oversold
A low-price solar quote often hides compromises on equipment, warranties, or system size. This guide shows you how to read and compare quotes — and which questions to ask before you sign anything.
What Is a Right-Sized Solar System?
Right-sizing means building a solar system around what your home actually needs — after efficiency improvements — not around your current, often inflated, usage. Here's what that looks like in practice.
Solar Plus Windows: When It Makes Sense
For homes with old or inefficient windows, replacing them before going solar can reduce the number of panels you need — cutting your total project cost. Here's how to decide which to do first.
Solar Plus Siding: When It Makes Sense
For homes with old siding or poorly insulated walls, addressing the building envelope before solar can reduce your load — and your solar system cost. Here's how the two work together.
How to Lower Your Electric Bill Before Installing Solar
The best solar system is a system sized around a lower bill. This guide walks through every step — from no-cost behavior changes to major efficiency upgrades — that Illinois homeowners can take before going solar.
12 Questions to Ask Before Choosing a Solar Company
Before you sign a solar contract, these 12 questions will reveal whether a company is giving you a real energy plan — or just a panel count. Most installers aren't ready for all of them.
Heat Pumps and Solar: How They Work Together
Replacing a gas furnace with a heat pump shifts your heating to electricity — which solar can then offset. Here's how to think about the heat pump + solar combination and what it means for sizing.
Solar Batteries and Backup Power: What to Consider
A home battery can keep your lights on during an outage and reduce what you buy from the grid. But it's not the right choice for every home. Here's how to evaluate whether battery storage makes sense for you.
How to Reduce Business Energy Costs Before Installing Solar
The efficiency-first principle applies to commercial properties too. Reducing your building's energy waste before sizing solar leads to a better investment — and a smaller required system.
Commercial Solar Plus Battery Storage: When It Makes Sense
For businesses facing demand charges or outage risk, adding battery storage to commercial solar can improve the economics significantly. Here's how to evaluate the combination.
How to Compare Commercial Solar Quotes Without Getting Oversold
Commercial solar proposals are often complex documents with room for significant variation. This guide helps business owners know what to look for — and what to question.
Questions Business Owners Should Ask Before Choosing a Commercial Solar Company
Commercial solar is a significant capital decision. These questions help business owners vet solar companies and proposals before committing.
What Is a Right-Sized Commercial Solar System?
The same right-sizing principle that applies to homes applies to commercial buildings. Here's how businesses should think about solar system sizing — and why bigger isn't automatically better.
Geothermal and Solar: What Homeowners Should Know
Geothermal is the most efficient heating and cooling system available. Paired with solar, it's a powerful combination — but one that requires careful planning. Here's what to consider.
Windows, Siding, and Solar: How Building Envelope Upgrades Affect Energy Use
Your home's envelope — its windows, walls, and siding — determines how much energy escapes. Tighten the envelope first, and your solar system can be smaller, cheaper, and better matched to real need.
For Homeowners
Get a Free Home Energy Assessment
SPM reviews your home's efficiency before recommending solar. We look for windows, HVAC, siding, and insulation opportunities that shrink the system size you need.
Get My Free Estimate →For Businesses
Schedule a Commercial Energy Review
SPM evaluates commercial properties for solar, battery storage, heat pumps, and building efficiency — in the right sequence for your energy goals and budget.
Learn About Commercial Solar →