[{"data":1,"prerenderedAt":452},["ShallowReactive",2],{"page-\u002Fmethodology":3,"author-mike":415},{"id":4,"title":5,"author":6,"bare":7,"body":8,"dateModified":389,"datePublished":389,"description":390,"extension":391,"howToSteps":392,"kits":392,"layout":393,"meta":394,"navigation":395,"path":396,"schemaType":397,"seo":398,"sources":399,"stem":409,"targetKeywords":410,"titleTag":413,"translationOf":392,"__hash__":414},"content\u002Fmethodology.md","How we work out the savings","mike",false,{"type":9,"value":10},"minimark",[11,18,23,31,34,38,90,126,129,133,168,171,175,178,232,235,239,289,292,304,308,314,317,322,325,329,369,373,376,379,383,386],[12,13,14],"answer-box",{},[15,16,17],"p",{},"Every dollar figure on this site comes from one chain: how much sun falls on your spot, times how well your panel is pointed at it, times how much of what it makes you actually use, times what a kilowatt-hour costs you. Exported power is valued at zero. The inputs are published below so you can disagree with them.",[19,20,22],"h2",{"id":21},"step-1-how-much-sun","Step 1 — How much sun",[15,24,25,26,30],{},"We use NREL's PVWatts data. For Orange County, a kilowatt of panel at optimal tilt produces roughly ",[27,28,29],"strong",{},"1,586 kilowatt-hours a year",". Coastal California varies by about ten percent either side of that; the Central Valley is higher, the far north lower.",[15,32,33],{},"That's the ceiling. Everything after this reduces it.",[19,35,37],{"id":36},"step-2-how-well-its-pointed","Step 2 — How well it's pointed",[39,40,41,54],"table",{},[42,43,44],"thead",{},[45,46,47,51],"tr",{},[48,49,50],"th",{},"Direction the panel faces",[48,52,53],{},"Factor",[55,56,57,66,74,82],"tbody",{},[45,58,59,63],{},[60,61,62],"td",{},"South",[60,64,65],{},"1.00",[45,67,68,71],{},[60,69,70],{},"West",[60,72,73],{},"0.83",[45,75,76,79],{},[60,77,78],{},"East",[60,80,81],{},"0.80",[45,83,84,87],{},[60,85,86],{},"North",[60,88,89],{},"0.35",[39,91,92,101],{},[42,93,94],{},[45,95,96,99],{},[48,97,98],{},"How it's mounted",[48,100,53],{},[55,102,103,110,118],{},[45,104,105,108],{},[60,106,107],{},"Tilted toward the sun",[60,109,65],{},[45,111,112,115],{},[60,113,114],{},"Flat on the ground or a deck",[60,116,117],{},"0.88",[45,119,120,123],{},[60,121,122],{},"Vertical, hanging on a railing",[60,124,125],{},"0.62",[15,127,128],{},"The vertical figure surprises people, and it's why we push tilt brackets so hard. Hanging a panel flat against a railing throws away nearly 40 percent of what the same panel would make angled up. A $60 bracket recovers most of it.",[19,130,132],{"id":131},"step-3-shade","Step 3 — Shade",[39,134,135,143],{},[42,136,137],{},[45,138,139,141],{},[48,140],{},[48,142,53],{},[55,144,145,152,160],{},[45,146,147,150],{},[60,148,149],{},"Wide open sky",[60,151,65],{},[45,153,154,157],{},[60,155,156],{},"Partly blocked — a building, a tree, the balcony above",[60,158,159],{},"0.75",[45,161,162,165],{},[60,163,164],{},"Mostly blocked — sun for a couple of hours",[60,166,167],{},"0.45",[15,169,170],{},"These are deliberately coarse. Real shade analysis needs a sun path study, and the honest position is that a three-way question gets you close enough to know whether to buy.",[19,172,174],{"id":173},"step-4-how-much-of-it-you-actually-use","Step 4 — How much of it you actually use",[15,176,177],{},"This is the number that most calculators skip and it's worth more than the panel choice.",[39,179,180,190],{},[42,181,182],{},[45,183,184,187],{},[48,185,186],{},"Household",[48,188,189],{},"Share of production consumed on site",[55,191,192,200,208,216,224],{},[45,193,194,197],{},[60,195,196],{},"Someone home most days",[60,198,199],{},"75%",[45,201,202,205],{},[60,203,204],{},"Someone home a couple of days a week",[60,206,207],{},"62%",[45,209,210,213],{},[60,211,212],{},"Empty from morning to evening",[60,214,215],{},"45%",[45,217,218,221],{},[60,219,220],{},"Business open during the day",[60,222,223],{},"90%",[45,225,226,229],{},[60,227,228],{},"Any of the above, plus a 1–2 kWh battery",[60,230,231],{},"up to 90%",[15,233,234],{},"We nudge these up slightly for households with large bills, since a bigger baseline load absorbs more of a small panel's output, and down slightly for very small bills. The nudge is capped at 92 percent — a big bill can never imply a perfect match.",[19,236,238],{"id":237},"step-5-what-a-kilowatt-hour-is-worth","Step 5 — What a kilowatt-hour is worth",[39,240,241,254],{},[42,242,243],{},[45,244,245,248,251],{},[48,246,247],{},"Utility",[48,249,250],{},"Average residential rate used",[48,252,253],{},"As of",[55,255,256,267,278],{},[45,257,258,261,264],{},[60,259,260],{},"Southern California Edison",[60,262,263],{},"33.2¢ (including the California Climate Credit)",[60,265,266],{},"1 June 2026",[45,268,269,272,275],{},[60,270,271],{},"San Diego Gas & Electric",[60,273,274],{},"45.7¢",[60,276,277],{},"January 2026",[45,279,280,283,286],{},[60,281,282],{},"Pacific Gas & Electric",[60,284,285],{},"39.25¢",[60,287,288],{},"March 2026",[15,290,291],{},"We use a blended average rather than a time-of-use figure by default, because most people don't know their rate plan and a blended average is the honest middle. On the utility pages we show what changes if you're on a time-of-use plan, where offsetting evening consumption is worth substantially more.",[15,293,294,297,298,303],{},[27,295,296],{},"Exported power is valued at zero."," SB 868 provides no export compensation. If you already have rooftop solar on a net billing tariff with a bidirectional meter, your situation is different — ",[299,300,302],"a",{"href":301},"\u002Fguides\u002Falready-have-rooftop-solar","see this guide",".",[19,305,307],{"id":306},"the-whole-thing-in-one-line","The whole thing in one line",[15,309,310],{},[311,312,313],"code",{},"annual saving = 1,586 × kW × direction × mounting × shade × self-consumption × rate",[15,315,316],{},"A 900-watt kit, west-facing, on a railing, wide open sky, someone home most days, on SCE:",[15,318,319],{},[311,320,321],{},"1,586 × 0.9 × 0.83 × 0.62 × 1.00 × 0.75 × $0.332 ≈ $183 a year",[15,323,324],{},"Add a tilt bracket and the mounting factor goes from 0.62 to 1.00, and the same kit makes about $295. That single change is worth more than a second panel.",[19,326,328],{"id":327},"what-we-dont-model","What we don't model",[330,331,332,339,345,351,357,363],"ul",{},[333,334,335,338],"li",{},[27,336,337],{},"Weather in a particular year."," PVWatts uses typical meteorological data. A wet winter costs you.",[333,340,341,344],{},[27,342,343],{},"Dust."," A dirty panel loses a few percent. Rinse it occasionally.",[333,346,347,350],{},[27,348,349],{},"Inverter clipping."," On the brightest days a panel can briefly out-produce its inverter. Small effect, real.",[333,352,353,356],{},[27,354,355],{},"Degradation."," Panels lose roughly half a percent of output a year. We ignore it in year one.",[333,358,359,362],{},[27,360,361],{},"Rate changes."," California electricity prices have risen steadily. We hold the rate flat, which makes our figures conservative.",[333,364,365,368],{},[27,366,367],{},"Any tax credit."," The federal 30 percent credit ended for expenditures after 31 December 2025 and there's no state equivalent. If a figure elsewhere looks better than ours, check whether it's still subtracting it.",[19,370,372],{"id":371},"measured-versus-estimated","Measured versus estimated",[15,374,375],{},"Everything above is a model. Models are wrong in interesting ways.",[15,377,378],{},"We're running a kit on a west-facing balcony in Irvine and logging what it makes.",[380,381],"measured",{"note":382},"Predicted annual production, actual to date, and the gap — published here once there is a season of data. We publish the comparison whichever way it runs.",[15,384,385],{},"When there's enough data we'll publish the comparison, including if it makes our model look bad. That's the point of measuring.",[387,388],"sources-block",{},"2026-09-01","The irradiance data, orientation factors, self-consumption assumptions and rate figures behind every number on this site. Including what we don't model.","md",null,"article",{},true,"\u002Fmethodology","Article",{"title":5,"description":390},[400,403,406],{"title":401,"url":402,"accessed":389},"NREL PVWatts Calculator","https:\u002F\u002Fpvwatts.nrel.gov\u002F",{"title":404,"url":405,"accessed":389},"SCE Rate Advisory, June 2026","https:\u002F\u002Fwww.sce.com\u002Fsave-money\u002Frates-financing\u002Fsce-rate-advisory",{"title":407,"url":408,"accessed":389},"CPUC Net Billing Tariff (NEM 3.0) decision, December 2022","https:\u002F\u002Fwww.cpuc.ca.gov\u002Fnembt","methodology",[411,412],"balcony solar savings calculation","how to calculate solar savings California","Our Savings Model, Explained | SmallSolarCo Methodology","nAeVADomj_3fZXDX0TWWJGcO-sts9dnqylMvBOZ3kJU",{"id":416,"title":417,"body":418,"description":443,"email":442,"extension":391,"location":444,"meta":445,"name":424,"navigation":395,"path":446,"photo":447,"role":448,"sameAs":392,"seo":449,"stem":450,"__hash__":451},"authors\u002Fauthors\u002Fmike.md","Mike",{"type":9,"value":419},[420,426,429,433,436],[15,421,422,425],{},[27,423,424],{},"Mike Yu"," started SmallSolarCo 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. He is not an electrician, a solar installer, or a lawyer, and the site says so wherever it matters. 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.",[15,427,428],{},"Since September 2026 he has been running a plug-in kit on that balcony and logging what it actually produces. Every measured figure on this site comes from that kit. Everything else is labelled as an estimate.",[19,430,432],{"id":431},"editorial-independence","Editorial independence",[15,434,435],{},"We don't accept review units on terms that involve anyone approving the review first. If a manufacturer sends us a kit, we say so on the review, and we keep the right to publish a bad one.",[15,437,438,439,303],{},"Reach him at ",[299,440,442],{"href":441},"mailto:hello@smallsolarco.com","hello@smallsolarco.com","Mike Yu started SmallSolarCo 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. He is not an electrician, a solar installer, or a lawyer, and the site says so wherever it matters. 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.","Irvine, California",{},"\u002Fauthors\u002Fmike","\u002Fimages\u002Fauthors\u002Fmike.jpg","Founder",{"description":443},"authors\u002Fmike","kb0uodhMlGk_YV3nMOIXdr6bpZgtB5zNoRxdGxsXMQ8",1788387857741]