[{"data":1,"prerenderedAt":247},["ShallowReactive",2],{"page-\u002Fguides\u002Fthe-question-calculators-forget":3,"author-mike":189},{"id":4,"title":5,"author":6,"bare":7,"body":8,"dateModified":168,"datePublished":168,"description":169,"extension":170,"howToSteps":171,"kits":171,"layout":172,"meta":173,"navigation":174,"path":175,"schemaType":176,"seo":177,"sources":178,"stem":182,"targetKeywords":183,"titleTag":187,"translationOf":171,"__hash__":188},"content\u002Fguides\u002Fthe-question-calculators-forget.md","The one question every solar calculator forgets to ask","mike",false,{"type":9,"value":10},"minimark",[11,18,23,26,89,92,95,99,102,109,112,116,119,125,131,137,148,152,159,162,165],[12,13,14],"answer-box",{},[15,16,17],"p",{},"Is anyone home during the day? That single question moves the savings from a plug in solar system by up to 40 percent — more than the choice of kit, more than a battery, more than anything except which way the panel faces. Almost no solar calculator asks it, because the industry grew up in an era when exported power was paid at the retail rate and it genuinely didn't matter. It matters enormously now.",[19,20,22],"h2",{"id":21},"the-arithmetic","The arithmetic",[15,24,25],{},"Take an 800-watt system on a west-facing Irvine balcony, tilted, open sky. It produces about 1,050 kilowatt-hours a year.",[27,28,29,45],"table",{},[30,31,32],"thead",{},[33,34,35,39,42],"tr",{},[36,37,38],"th",{},"Household",[36,40,41],{},"Share used at home",[36,43,44],{},"Value at 33.2¢",[46,47,48,63,76],"tbody",{},[33,49,50,54,57],{},[51,52,53],"td",{},"Someone home most days",[51,55,56],{},"75%",[51,58,59],{},[60,61,62],"strong",{},"$262",[33,64,65,68,71],{},[51,66,67],{},"Home a couple of days a week",[51,69,70],{},"62%",[51,72,73],{},[60,74,75],{},"$217",[33,77,78,81,84],{},[51,79,80],{},"Empty from morning to evening",[51,82,83],{},"45%",[51,85,86],{},[60,87,88],{},"$157",[15,90,91],{},"Same panel. Same balcony. Same city. Same weather. A $105 spread, which is 40 percent of the return, decided entirely by whether anyone's in.",[15,93,94],{},"Now compare that to the things people actually agonise over. Choosing a premium panel over a budget one might get you 5 percent more output. Adding a third panel to a two-panel setup adds maybe $60. Neither is close.",[19,96,98],{"id":97},"why-it-stopped-mattering-and-started-again","Why it stopped mattering and started again",[15,100,101],{},"Under the old net metering rules, exported power was credited at close to the retail rate. Your meter effectively ran backwards. Whether you used your production at noon or bought it back at 8pm was very nearly a wash, so nobody modelled it and nobody asked.",[15,103,104,105,108],{},"The CPUC's net billing decision in December 2022 changed that for rooftop solar, cutting export compensation to avoided-cost rates. And SB 868 goes further: it's silent on export compensation entirely, which means for a plug-in device, exported power is worth ",[60,106,107],{},"zero",".",[15,110,111],{},"So a kilowatt-hour you use is worth 33 cents and a kilowatt-hour you export is worth nothing. That's not a discount. That's the whole value of the thing, present or absent, depending on whether somebody happened to be running a dishwasher.",[19,113,115],{"id":114},"what-you-can-do-about-it-free","What you can do about it, free",[15,117,118],{},"This is the part that makes the question worth asking rather than just interesting.",[15,120,121,124],{},[60,122,123],{},"Move one load into daylight."," Set the dishwasher for 1pm rather than 8pm. Run the washing machine at lunchtime. If you have a timer on a water heater or a pool pump, move it. On a time-of-use plan you're shifting electricity from a 58-cent window to one where your panel covers it — worth roughly $60 a year for a single daily cycle, and it costs nothing.",[15,126,127,130],{},[60,128,129],{},"Pre-cool in summer."," Run the air conditioning harder at 2pm and let the house coast through the evening. Free, effective, and the house is more comfortable at 6pm.",[15,132,133,136],{},[60,134,135],{},"Charge things at midday."," Laptops, tools, an e-bike, a portable power station. Anything with a battery is a load you can move.",[15,138,139,142,143,108],{},[60,140,141],{},"Think about it before you buy a battery."," A battery is the equipment answer to this problem and it costs $800 to $1,500. Two timers cost nothing. Do the free things first, measure what changes, then decide. ",[144,145,147],"a",{"href":146},"\u002Fguides\u002Fbattery-or-no-battery","The battery decision",[19,149,151],{"id":150},"why-we-ask-it-in-the-calculator","Why we ask it in the calculator",[15,153,154,158],{},[144,155,157],{"href":156},"\u002Fsavings-calculator","Our calculator"," asks seven questions and this is the fourth. We phrase it as \"is anyone usually home during the day\" rather than \"what's your self-consumption ratio,\" because those are the same question and only one of them can be answered by a person.",[15,160,161],{},"It's also the question that most often turns a yes into a marginal, and occasionally into a no. A west-facing balcony with good sun and an empty flat produces a figure low enough that we'd rather you knew before buying than after.",[15,163,164],{},"That's uncomfortable for a site that earns commission on kits. It's also the reason to trust the number when it comes back high.",[166,167],"sources-block",{},"2026-09-01","Whether someone's home during the day changes your solar savings by up to 40%. It's the biggest lever in the model and no calculator asks about it.","md",null,"article",{},true,"\u002Fguides\u002Fthe-question-calculators-forget","Article",{"title":5,"description":169},[179],{"title":180,"url":181,"accessed":168},"CPUC Net Billing Tariff decision, December 2022","https:\u002F\u002Fwww.cpuc.ca.gov\u002Fnembt","guides\u002Fthe-question-calculators-forget",[184,185,186],"solar self consumption","does solar work if you're not home","solar savings work from home","The Solar Question Nobody Asks: Is Anyone Home?","AUSmAQZRt46VQekozd-x4142nUMWackqmy6A67NNek8",{"id":190,"title":191,"body":192,"description":238,"email":237,"extension":170,"location":239,"meta":240,"name":198,"navigation":174,"path":241,"photo":242,"role":243,"sameAs":171,"seo":244,"stem":245,"__hash__":246},"authors\u002Fauthors\u002Fmike.md","Mike",{"type":9,"value":193},[194,200,206,214,218,221,224,228,231],[15,195,196,199],{},[60,197,198],{},"Mike Yu"," is the editor of SmallSolarCo. He started it after working out that a plug-in panel was the only kind of solar available to him — he rents in Irvine with a west-facing balcony and no roof of his own — and found that nothing written about it in California was both plain and sourced.",[15,201,202,205],{},[60,203,204],{},"He is not an electrician, a solar installer, or a lawyer",", and the site says so wherever it matters. What he does is read the primary sources — bill text, CPUC filings, utility tariff sheets, UL standards, manufacturer specification sheets — and put them in one place with the arithmetic attached and a date on every claim.",[15,207,208,209,213],{},"He has a background building web products, and built the savings model here himself, using NREL irradiance data and Southern California Edison's published rates. It's published in full on ",[144,210,212],{"href":211},"\u002Fmethodology","the methodology page",", and the site's tests fail if an article and the calculator ever disagree.",[19,215,217],{"id":216},"what-this-site-does-and-doesnt-do","What this site does and doesn't do",[15,219,220],{},"It explains, catalogs, and calculates. It does not test hardware. Kit pages are built from published specifications with the date they were checked, not from a test bench, and the site says so rather than implying otherwise.",[15,222,223],{},"There is a plug-in kit on the Irvine balcony logging output, which is used to check whether the model is roughly calibrated. Figures from it are labelled measured and carry their conditions. Everything else on the site is labelled as an estimate, and there are far more estimates than measurements.",[19,225,227],{"id":226},"editorial-independence","Editorial independence",[15,229,230],{},"Affiliate commissions don't reach the savings model — it's the same arithmetic for every kit, and the current recommendation for anyone spending under $400 is a nonprofit that pays nothing. We don't accept hardware on terms that involve anyone approving coverage first. If a manufacturer sends something, the page says so.",[15,232,233,234,108],{},"Reach him at ",[144,235,237],{"href":236},"mailto:hello@smallsolarco.com","hello@smallsolarco.com","Mike Yu is the editor of SmallSolarCo. He started it after working out that a plug-in panel was the only kind of solar available to him — he rents in Irvine with a west-facing balcony and no roof of his own — and found that nothing written about it in California was both plain and sourced.","Irvine, California",{},"\u002Fauthors\u002Fmike","\u002Fimages\u002Fauthors\u002Fmike.jpg","Founder and editor",{"description":238},"authors\u002Fmike","2UYfVkomBje4XbTXMc-HWSa7jliDKILElV8MEZxfPVw",1788880326525]