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A 1-minute screen for whether your electrical service likely has room for solar, a battery or an EV charger.
A rough screen, not an electrical assessment. Adding solar, a battery or an EV charger can require panel capacity under the NEC 120% rule — a licensed electrician confirms your service. iSolar (and Three Rivers Electric) handle any upgrade or load-management needed.
Solar, storage and EV charging all interact with your main electrical panel. The National Electrical Code limits how much you can back-feed or load a given busbar (the “120% rule”), so an older 100-amp service or one already running an EV, AC and electric appliances can be tight. The good news: the answer is often simple load management, not a full upgrade — and when an upgrade is the right call, we and Three Rivers Electric handle it cleanly, permitted and inspected.
This is a 60-second screen, not a full electrical assessment — here’s the logic behind the answer, so you know what it means and what it’s assuming about your panel.
NEC 705.12 lets your solar breaker plus your main breaker add up to no more than 120% of the busbar rating. On a 200-amp panel that’s a 240-amp ceiling, so a typical 40- to 50-amp solar backfeed fits with room to spare. On an older 100-amp service the same array can blow right past it — which is why this screen leans so hard on your panel size.
The rating that matters is stamped on the panel’s busbar inside the box, not on the meter or the service drop. Two homes both sold as “200-amp service” can have different busbars. This tool assumes your busbar matches the main-breaker size you picked — a licensed electrician confirms the stamp.
Every big load you toggled — EV charger, central AC, electric range, dryer, water heater, hot tub — is already claiming room on the panel. A 200-amp service already running most of those can be tighter than a bare 100-amp service, and the verdict weighs what you told it.
When a panel is tight, the fix is frequently a load-management device or a line-side tap — not a full service upgrade. We and Three Rivers Electric tell you straight which one your panel actually needs, permitted and inspected either way.
A panel can have the amps but no open slots left for new breakers. This screen can’t see how full your panel is — an electrician counts the spaces and checks whether a tandem breaker or a sub-panel solves it.
Code allows a measured load calculation (NEC 220) based on your actual demand, which often frees up more room than the nameplate math here suggests. When it’s close, we run that calc on site before anyone quotes an upgrade.
The service-entrance conductors, the meter socket, and the utility transformer all carry their own limits. A panel swap sometimes means a coordinated service upgrade with your utility — for most of our service area that’s Xcel — and we file the application and handle the utility side.
Any grid-tied solar or battery system needs an interconnection application through your utility (Xcel for most Minnesota homes), and your local city or county AHJ permits and inspects the work. This verdict is a first look to see if it’s worth a conversation — not a green light.
Not sure this is the right tool? This is the quick 30-second panel screen. For the whole-house picture, take the Is My House Ready for Solar? assessment — eight questions on roof, panel and shading. Planning specific loads? Size a home battery or an EV charger.
Maybe. Solar back-feeds your panel and an EV charger is a big continuous load, so a small (100 A) or already-loaded service can run out of room under the NEC 120% rule. Often the fix is load management rather than a full upgrade — a licensed electrician confirms.
Usually replacing the main panel and/or service entrance (commonly 100 A to 200 A) so you have capacity for solar, storage and EV charging. We coordinate with your utility and pull permits.
Yes — iSolar handles the solar/EV/battery electrical, and our sister company Three Rivers Electric does full-service electrical, including upgrades.
NEC 705.12 caps the sum of your main breaker and your solar backfeed breaker at 120% of the busbar rating. A 200-amp busbar allows up to 240 amps of combined breaker, so a 40-amp solar breaker sits comfortably alongside a 200-amp main. Drop to a 100-amp panel and that ceiling is 120 amps — the same array often won’t fit without load-side changes or a service upgrade.
No — this is the quick, one-question panel screen. The readiness quiz is the fuller eight-question assessment that also looks at roof age, orientation, shading and your utility. If the panel is your only question, stay here; if you want the whole-house picture, take the quiz.
Yes. Any grid-tied solar or battery system needs an interconnection application before it’s energized — through Xcel for most of our service area — and your city or county inspects the electrical work. We prepare that paperwork and pull the permits as part of the job, so you don’t chase it.
It happens often. A physically full 200-amp panel can still take solar with a tandem breaker, a sub-panel, or a line-side (supply-side) tap that lands ahead of the main. We and Three Rivers Electric pick the cleanest option for your box rather than defaulting to a full upgrade.
These tools are ballparks — a free assessment gives you exact, site-specific figures.