[{"data":1,"prerenderedAt":221},["ShallowReactive",2],{"page-\u002Fguides\u002Falready-have-rooftop-solar":3,"author-mike":184},{"id":4,"title":5,"author":6,"bare":7,"body":8,"dateModified":163,"datePublished":163,"description":164,"extension":165,"howToSteps":166,"kits":166,"layout":167,"meta":168,"navigation":169,"path":170,"schemaType":171,"seo":172,"sources":173,"stem":177,"targetKeywords":178,"titleTag":182,"translationOf":166,"__hash__":183},"content\u002Fguides\u002Falready-have-rooftop-solar.md","You already have rooftop solar. Read this first","mike",false,{"type":9,"value":10},"minimark",[11,18,23,26,29,32,35,90,102,106,109,112,115,122,126,132,138,144,148,151,154,160],[12,13,14],"answer-box",{},[15,16,17],"p",{},"Adding a plug-in panel to a home that already has rooftop solar usually doesn't pay. Your roof is probably already covering your daytime consumption, so the plug-in panel's output would be exported rather than used — and exports under California's net billing tariff are compensated at a fraction of the retail rate. There's also a real risk that adding generation affects your existing interconnection agreement. Talk to your installer before you buy anything.",[19,20,22],"h2",{"id":21},"why-the-arithmetic-changes","Why the arithmetic changes",[15,24,25],{},"For everyone else, the case for plug-in solar rests on avoiding a 33-cent purchase. You make power, you use it, you don't buy it.",[15,27,28],{},"If you already have rooftop solar, your daytime consumption is probably already covered. A plug-in panel's output arrives at a moment when your home isn't buying anything anyway. So it doesn't avoid a purchase — it adds to an export.",[15,30,31],{},"And exports are compensated poorly. California's net billing tariff, adopted by the CPUC in December 2022, pays new solar customers avoided-cost rates for exported energy — typically in the range of 5 to 8 cents rather than the retail 33.",[15,33,34],{},"So the same panel that saves a renter 33 cents a kilowatt-hour earns you perhaps 6.",[36,37,38,53],"table",{},[39,40,41],"thead",{},[42,43,44,47,50],"tr",{},[45,46],"th",{},[45,48,49],{},"Renter, no other solar",[45,51,52],{},"Homeowner with rooftop solar",[54,55,56,68,79],"tbody",{},[42,57,58,62,65],{},[59,60,61],"td",{},"What a produced kWh is worth",[59,63,64],{},"~33¢ (avoided purchase)",[59,66,67],{},"~5–8¢ (export credit)",[42,69,70,73,76],{},[59,71,72],{},"800W kit, annual value",[59,74,75],{},"~$262",[59,77,78],{},"~$50",[42,80,81,84,87],{},[59,82,83],{},"Payback",[59,85,86],{},"~3 years",[59,88,89],{},"~17 years",[15,91,92],{},[93,94,95,96,101],"em",{},"Estimated. ",[97,98,100],"a",{"href":99},"\u002Fmethodology","Full working",".",[19,103,105],{"id":104},"the-interconnection-wrinkle","The interconnection wrinkle",[15,107,108],{},"There's a second issue, and it's the one to take seriously.",[15,110,111],{},"You have an interconnection agreement with your utility covering a system of a specific size. Adding generation can, depending on how it's characterised, put you outside that agreement.",[15,113,114],{},"SB 868 exempts compliant plug-in devices from interconnection requirements, which suggests the plug-in device shouldn't disturb your existing arrangement. But the interaction between the exemption and an existing net-billing agreement isn't something we've seen addressed anywhere — there is no published CPUC or utility guidance on it as of 1 September 2026 — and getting it wrong could affect the compensation on your main system, which is worth far more than a $600 panel.",[15,116,117,121],{},[118,119,120],"strong",{},"What we'd do:"," ask your installer, and ask your utility, before buying. Get the answer in writing.",[19,123,125],{"id":124},"when-it-might-still-make-sense","When it might still make sense",[15,127,128,131],{},[118,129,130],{},"Your roof system is undersized and you're still importing at midday."," Look at a sunny weekday on your utility's hourly usage data. If you're importing between 11am and 3pm, a plug-in panel is displacing real purchases and the ordinary arithmetic applies.",[15,133,134,137],{},[118,135,136],{},"You want it somewhere the roof doesn't reach"," — a detached workshop or garage on its own circuit that you'd rather not run a new feed to.",[15,139,140,143],{},[118,141,142],{},"You're on legacy net metering with retail-rate credits."," If you're on an older agreement where exports are credited at or near the retail rate, exporting isn't the loss it is under net billing. Check which agreement you're on before assuming.",[19,145,147],{"id":146},"the-better-version-of-this-idea","The better version of this idea",[15,149,150],{},"If your goal is more solar and you already have a roof full of it, the productive question is usually storage rather than another panel. A battery lets your existing system's exports — currently earning 6 cents — get used in the evening instead, when they'd otherwise cost you 33 or more.",[15,152,153],{},"That's a bigger purchase and a different article, but it's where the money is for you.",[15,155,156],{},[97,157,159],{"href":158},"\u002Fguides","Back to the guides →",[161,162],"sources-block",{},"2026-09-01","If you have rooftop solar on net billing, a plug-in panel probably exports at 5-8 cents instead of saving you 33. Usually not worth it.","md",null,"article",{},true,"\u002Fguides\u002Falready-have-rooftop-solar","Article",{"title":5,"description":164},[174],{"title":175,"url":176,"accessed":163},"CPUC Net Billing Tariff decision, December 2022","https:\u002F\u002Fwww.cpuc.ca.gov\u002Fnembt","guides\u002Falready-have-rooftop-solar",[179,180,181],"add solar panel to existing system","plug in solar with rooftop solar","NEM 3.0 additional panels","Adding Plug-In Solar When You Already Have Rooftop Solar","X3FYUDny2cDN9QtNjxkoBOKq1ZB6UM-yx2r9Ny_nN6w",{"id":185,"title":186,"body":187,"description":212,"email":211,"extension":165,"location":213,"meta":214,"name":193,"navigation":169,"path":215,"photo":216,"role":217,"sameAs":166,"seo":218,"stem":219,"__hash__":220},"authors\u002Fauthors\u002Fmike.md","Mike",{"type":9,"value":188},[189,195,198,202,205],[15,190,191,194],{},[118,192,193],{},"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.",[15,196,197],{},"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.",[19,199,201],{"id":200},"editorial-independence","Editorial independence",[15,203,204],{},"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.",[15,206,207,208,101],{},"Reach him at ",[97,209,211],{"href":210},"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":212},"authors\u002Fmike","kb0uodhMlGk_YV3nMOIXdr6bpZgtB5zNoRxdGxsXMQ8",1788387858562]