Completed: Dream shop power implementation (and off grid capable residence)

[dcg9381]

I've been working on this for almost 4 years. I've done about 80% of the electrical work, 100% of the shop work, and 10% of the residential work. I've made a few mistakes, learned a lot, but I think I've got it pretty well setup now. In true GJ style, we've been living in our shop for about 2 years - as facilitated by having an RV (kitchen/bath) while I could build the "living" part of the shop out... Course, then while the construction industry was impacted by Covid and market pressure - so this took WAY too long.

I'm lucky to have a spouse/partner that will put up with this stuff and takes up the slack while I work on this stuff.

We've basically finished the residence this week - which allows me to "unpack" the shop and eventually get back to regular projects. Well, after a bunch of detail work.

The electrical setup is substantial and somewhat complex. We've got a current solar array, designed for future solar array, are setup to handle several RVs (guests), have a large generator, along with the usual GJ 240V shop needs. Our sewer system (septic) is entirely gravity function and our water source is collected rain - so this setup is true off-grid capable...

I've got "power monitoring" - many of you would be surprised that we're peaking under 10KW during moderate days...

 

[theoldwizard1]

What tells the load shed switches to turn off the load (assuming no grid) ?

 

[Daveyclimber]

Getting ready to do something similar myself. Keep posting updates.

 

[Lightning rod]

interesting setup.
question on the PV's
you feed directly to the grid only or is there a battery bank not shown on the single line diagram?

thanks for sharing

 

[dcg9381]

What tells the load shed switches to turn off the load (assuming no grid) ?

It took me a while to figure these things out, because there are no control wires to the generator. And Generac consumer support basically says, "we just read the manuals".

They are fairly dumb devices. All they are is fancy turn-on timers that control a big relay. When power drops out, the relay opens, and a count-down timer is started when generator power comes up. The load shed device turns back on some minutes after a power outage. You set them up so they come on at different times so they don't strain the genset.

IF they detect below 58hz power frequency this means the generator is losing RPM to the load and they turn off again, only to try again at their pre-set timing interval.. We have two load-sheds, but looking at our current power use, we're not even close to generator capacity. They will help "soft load" the generator though.

 

[dcg9381]

you feed directly to the grid only or is there a battery bank not shown on the single line diagram?

Yes, the most "economical" use case for these in terms of payback (with my utility) is just have them net meter into the grid. My utility credits me KWh per KWh if I produce, as long as my bill is more than $0 at the end of a month. This is the fastest way to "pay" for the cost of a PV system.

The downside is that they do nothing in the event of a grid failure. They shut down and stay down until the grid comes back on. I think there are better options of controlling PV with a generator now, but they are pretty new.


Batteries are expensive, require maintenance, and it takes a BIG bank to provide enough power to run something like HVAC. The Tesla Powerwall (and similar) systems - the only way I'm interested is if I have a change rate utility structure, so I can use battery power when the utility is "expensive" and charge when it is cheap.