[RE-wrenches] Balcony solar

[Tom McCalmont]

I believe it’s safe using modern inverters that meet UL1741.  There obviously needs to be assurance that solar generation cuts off within milliseconds if a toddler unplugs the feed from an outlet.

Balcony solar has been widely deployed in Europe (Germany especially) for quite some time now, so several advocates are working to bring it to the U.S.  Utah (surprisingly) was the first state to adopt it.  The bill being considered in CA where we are will bring a lot of momentum to the idea nationally if it passes.

You raise a good point about the meter.  Most utility meters are the ratcheting type now, meaning they count up no matter which way the power flows through them.  That was instituted many years ago when scab customers figured out they could turn their electric meter upside down to cause it to count down when they were consuming.  So utilities have mostly replaced those older meters with ratcheting or smart meters that always count up.  It’s why in most states you have to have an interconnection agreement with the utility to install a solar system and why your meter is replaced with one that is capable of counting backwards.

The theory is that a balcony solar system at 1.2 kW will never produce more power than is needed to offset phantom loads within the house so will never actually backfeed (or cause the meter to count up).  That’s likely the case in most houses that existing loads are always consuming at least 10A (1200W).

Tom McCalmont, P.E.
CEO, Paired Power
pairedpower.com <http://pairedpower.com/> | LinkedIn <https://www.linkedin.com/company/paired-power/>
Direct: (669) 877-2931




> On May 20, 2026, at 8:25 AM, Jay via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
> 
> Hi all. 
> 
> I’m wondering what/if there is consensus about this. 
> I just read Cali is approving 1200 watts into an outlet. Which seems absolutely dangerous. 
> I haven’t been able to figure out how the utility deals with backfeed. 
> Does the meter count up or down or do nothing?
> 
> Just wondering
> 
> Jay
> 
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