California adds 8,000 home batteries a month. Current rules lock them out of energy markets. SB 913 would change that; letting aggregators bundle your battery into a virtual power plant and pay you during peak demand. Full breakdown on WattBuild →

"Fannie Mae will finance your off-grid home" is one of the most repeated claims in off-grid forums. We checked their actual selling guide. It's effectively false. The realistic path: portfolio loans from local banks, 25-35% down. Full breakdown on Watt...

A 200Ah AGM battery and a 200Ah LiFePO4 battery have the same label. But one gives you 100Ah of usable energy. The other gives you 160Ah. That gap changes how you size an off-grid battery bank: and what it actually costs over 10 years. Full breakdown o...

Hawaii: ~100% of new solar installs include a battery. Illinois: 25%. Most states: under 10%. The difference isn't climate, it's rate structure and policy. We mapped the data state by state. Full breakdown on WattBuild →

Every other SGIP battery rebate in California is gone. The last one standing pays $1,100/kWh and can cover your entire system cost. The catch: you need to be income-qualified. And it's already on a waitlist. What that actually means for CA homeowners →

Your power station's AC outlet is burning 10-20% of the battery on conversion losses before power even reaches your laptop. USB-C PD skips the inverter: one conversion step instead of two. We broke down the math and the edge cases →

Flexible solar panels flush-mounted to a roof hit 70C in summer: an 18% output penalty before degradation even starts. That heat accelerates yellowing, delamination, and micro-cracks. NREL data: they degrade ~60% faster than rigid panels. Full breakdown →

Three HVAC refrigerant transitions in 40 years; roughly one every 15-20 years. None ever required homeowners to replace working equipment. Your R-410A system is fine. The real cost? Service gets expensive as old refrigerant supply shrinks. Full breakdo...

Most people think you can cancel any contract in California within 3 days. You can't. But if a solar company signed you at your kitchen table, you probably can; and seniors get 5 days, not 3. Full breakdown on WattBuild →

Enphase has a formal upgrade program for owners of legacy microinverters, and it now includes battery storage at potentially discounted pricing. ~300,000 M-series homeowners are eligible. One thing nobody warns you about: those batteries make your gara...

NC's solar rebates were so popular, slots sold out in 21 minutes. Duke Energy switched to a literal lottery, and 2,900 people still walked away empty-handed. The program's gone now. So is the federal tax credit. Here's what's left for NC homeowners →

Everyone shops mini-splits by maximum BTU. The spec that actually determines your comfort? Minimum output. Mitsubishi's best units run at 1,600 BTU/h, lower than a hair dryer on low. No other brand matches that efficiently. Full breakdown on WattBuild →

Most homeowners assume they should take their solar panels when they move. The actual relocation cost, $5,000 to $15,000+, often approaches a brand-new system. Why starting fresh usually wins →

Some solar installers skip metal flashing and just squirt sealant into the bolt hole. Building codes require flashing at every roof penetration; sealant alone doesn't qualify. Sealant cracks from thermal cycling and UV. Low-quality formulations fail in...

"Mount your panels vertical in Alaska": common advice that's only half right. UAF research: 70 degrees is the real sweet spot. Vertical costs you ~30% of annual output. The surprise: spring is peak Fairbanks solar season. Cold air + snow reflection + r...

83% of inspected solar projects have connector issues. The #1 cause? Mixing MC4 brands. They look identical. They're not. Different tolerances, different metals, no intermatability certification. NEC says it's a code violation. Field data says it's a f...

'Go bigger, just to be safe' makes sense for furnaces. For heat pumps, it backfires. An oversized unit short-cycles, leaves your home humid, and wears out the compressor faster. The fix isn't bigger equipment: it's a proper load calculation. Full break...

Heat pump water heaters 'cool your home for free' while heating water. But average cooling is ~520 BTU/hr. Your home needs ~21,000. That's 2.5%. The real value? 60% lower water heating bills. We ran the field data.

One shaded cell can cut a solar panel's output by 75%. How? Series wiring turns every cell into a bottleneck. Bypass diodes fix this, but panels made before the mid-1990s might not have them. We broke down the science and what to check →

A 20% mismatch in internal resistance between parallel batteries cuts cycle life by 40%, MIT research. That's what happens when you add new batteries to an old bank. The new ones do most of the work and wear out first. Full breakdown on WattBuild →

$350/kWh in upfront rebates, plus $0.10/kWh every time you discharge during peak hours. SDCP's Solar Battery Savings program is one of the most generous CCA battery incentives in California. The eligibility rules are specific. We break down what qualif...

Heat pumps need 1.5-3x more airflow than a gas furnace at the same capacity. The DOE minimum is 400 CFM/ton for cooling; furnace ducts are often sized for 300-350. If your home has never had AC, your ducts may be the bottleneck: not the equipment. Full...

Need just 4-5 solar panels? You will pay 2-3x more per watt than someone buying a full pallet of 30. The reason: shipping one panel costs the same as shipping twenty. LTL freight runs $287-$300 minimum regardless of quantity. Your small-quantity option...

SolarEdge says monitoring is free. It is, until you buy a home with solar and discover the installer controls your account. Your options and what to do before you get locked out →

Germany just hit 1 million balcony solar installations. Renters plug panels into wall outlets, save EUR 200-300/year, no landlord veto allowed. Utah legalized this for the US in 2025. 29 more states are considering it. Full story on what it takes to br...

Is solar worth it? Check your roof, calculate solar savings. Alternative to Project Sunroof

Is solar worth it? Check your roof, calculate solar savings. Alternative to Project Sunroof

It's an old concept executed more efficiently than ever before.

Best solar generator personalized for you. Compare brands and models. Compare battery, solar, inverter, price, size, weight. View price history.

Calculators to help you understand home solar, battery backup, and energy efficiency options.