Nominal Kw Rating of your PV System

I feel like this is a no-brainer but apparently its something easily overlooked. When the sense settings is asking for the Nominal Kw, is that in DC or AC? Kinda stupid that it doesn’t say it in the question.


kW AC - That’s what Sense is monitoring.


I think you attempted to reply to this in another thread:

What flows through you panel, which is what Sense is connected to, is always AC. DC from Solar is converted to AC before it gets to your panel. There’s no two ways to answer this. There’s only one current type that goes through your panel.

So, if it’s not clear from @kevin1 or myself here’s your one word answer:


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Yeah I was trying to edit the post to add the pics but there was no way to even see the post prior to its moderation. I do understand what you’re saying but its not something that is obvious or apparent to everyone. If someone is buys a 20Kw system, they are very likely to put in 20Kw when in fact that tends to be the DC power production. In my case, I purchased a 16.1Kw DC system that produces 14.98Kw AC.

It really cant be that hard to add a space and two extra letter to that question in the settings :slight_smile:

You make a good suggestion, but I think most grid-tied solar systems only offer an AC rating, because in the case of a grid-tied system, the DC rating is meaningless.

I am sorry, but I disagree with that.
Most inverters can produce 7-10% more AC power than they are labeled.
EG: I have seen enphase M250 produce 270 watt ac (given enough DC power to begin with)
When you pull a solar permit, you are always asked about DC kW capacity, never AC rating.
So I agree with addohm that a simple 3 characters " AC" would make it a lot more clear for everyone.


I agree that @addohm s suggestion would help. @dannyterhaar, you made me go back to look at my solar install - you’re right. No AC rating. Just DC W STC and DC W PTC. So I went back to the original inception of this solar feature. It ties back to California Title 24 compliance which looks for DC W STC. So I change my answer.


I would also agree that many people who have limited knowledge of their PV system and/or the way Sense works might be confused. Speaking from development experience it is easy to change:

Nominal kW rating of your PV system


Nominal kW AC rating of your PV system.

This however should be a request made in the product suggestion category or moved by a mod.

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+1 on @dannyterhaar’s comment. From what I’ve seen, PV systems are characterized by the DC name plate capacity of the panels. Panel ratings, of course, are based on ideal conditions that rarely occur. For that reason, many systems have less AC capacity.

The ratio of DC to AC capacity is the “inverter load ratio” - google it (eia dot gov link is recommended). Which value - AC or DC - is appropriate for Sense depends on what Sense is doing with it. Either way, it’s not a decisive factor, as the actual energy you generate will also depend on a lot of other things like panel tilt, which direction they’re facing, soiling, shading, time of day, time of year, etc.


No need to overcomplicate it. Remove the question all together by properly asking the question the first place. That was my basic point from the beginning.

Nominal kW AC rating of your PV system

Done, problem solved. I get that the guys at Sense expect AC because we’re measuring at AC but any average joe that buys a solar system will be buying it with the immediate knowledge of its DC production capacity.

Go get estimates. Excluding the company I purchased from, the first two companies off the top of my head that I got estimates from said I would need >16 kW Solar. This is about equal to what I purchased (DC), and it was not specified it was DC or AC. So naturally that’s the first number I would punch in and I wouldn’t ever really have any reason to change it.

The underlying feature in Sense, was designed to give California Title 24 compliance. That requires, as you suggest, the nameplate DC rating.

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