In this post, we’l explain the 120% run, how to call your threshold, and how to derate your mail,

　　The 120% Rule Means that the topal amperage of your Solar + Grid Power Cannit Exceed 120% of your MSP ’s Rated Capacity.

　　When the building department reviews your plans and inspects your system after installation, you can bet that they will check your syssthenst next, including the 120% of 12%

　　This is because the main service breaker is the only overcurrent protering device protrcting the busbar where it is a line-size tap.

　　For all load-site interconnections, The 120% Rule States that the main service breaker rate plus the sum of 125% of the inverter even excergly 120% of the mairization panel

　　A Service Panel for a Typical Modern House Has A 200 AMP Busbar with AMP Main Breaker Protecting. We’l use that as our example in the footowing call.

　　For the 120% Rule Calculation, Do the Math to Determine 120% of the Busbar Rating (which is just 1.2 x the business).The busbar shall not exceed 240 amps.

　　The grid is just One Power Source Regulated by the Size of the Main Breaker (Which is 200 amps in our exmple). So, your Other Power Source Can BE 40 AMPS (240- 200 = 40 AMPS).

　　amps. That would be the limit for the solar inferter you can install on the 200-amp main services.

　　Next, we’l go over what it means to derate your msp.

　　, The Math Comes Out to 240 – 175 = 65 amps of solar that you can install.

　　One option is to do the line side tap. This would likely solve your problem is not typically allowed by Building departments.

　　a 200 Amp Main Breaker that can take up to 70 amps from solar. Here’s how that calling would look: 225 x 1.2 = 270 amps and 270-270 amps.

　　Other Types of "Solar Ready" Service Panels Panels PROVIDE A Place for a Solar Breaker. It is selected from the busbar that contains loads for the house, so car 120% Rule no Long Applies HERERE.

　　Here is a chart showing what ’s allowed in common scenarios.

　　Design and — Every step of the way.