Building a "Whole House UPS"

[Bobfa]

A little backstory first:

I have several dead Lead Acid batteries from UPS in my garage and a couple of large ones from—sump Pump Backups. Like Akline batteries, I am tired of early failures and other issues around older technologies. I also have a 5.5KW gasoline generator that I can hook up to circuits in the house as needed. I removed a Manual transfer switch from service while planning this project.

I have several goals in mind.

1. Emergency sump pump power.
2. UPS for networking, computers, security, and refrigeration.
3. Emergency lighting, garage door, furnace.
4. Grid Charging
5. Possible/Probable PV installation for partial supply
6. Location is in Chicago Suburbs
7. The system is 240v split phase, but I have no critical loads that need it.


I call this a scalable whole-house UPS with an optional solar supply. We have worked for several years to reduce standby loads and eliminate heavy peak loads. I have a good handle on the total load.


Initial thoughts on system design.

I am considering using Victron equipment for control and looking at 48-volt battery systems to reduce current needs. The first thing I HAVE to power up are the sump pump 1/2 hp and the network+nas.

Bob

 

[MisterSandals]

Step 1:

Search results for query: energy audit

diysolarforum.com

 

[MillAlien]

The ‘energy audit’ template will help your determine your load so you can size your system‘s battery bank, inverter(s), and solar panels. You can’t really do anything without that. You might also slice and dice “critical“ loads. If you need to keep your sump pump alive but can live without everything else, example, that’s one thing. But it sounds like it’s the sump, network and nas that’s “critical”. The energy audit puts that all on the table. That process ends with a sizing outcome.

After that, design and installation is it’s own thing. If you‘re planning on DIY, start watching YouTube and don’t stop. There’s a shit-ton of considerations here, everything from physical constraints to electrical code.

Once you get all of that sorted, a good vendor can then help you package a kit that meets your needs, or you can go a la carte.

OR…the whole kit and kaboodle can subbed out to a local company that installs PV. They’ll do all of the above, including designing an expandable system.

We’re subbing out for a commercial building we own because we have to, but here at home I’d rather stick needles in my eyeball than hire anybody to do anything.

 

[Bobfa]

I have started the ”energy Audit”. I had to order a new clamp on Amp-meter to make that simpler!

I have a spreadsheet of the loads I want to run. Three levels, Critical (UPS Type stuff), Emergency (fridge, furnace, basic lights on each floor (maybe DC to avoid inverter loss), Then the rest.

One of the things that we are still working on is my 320W always on loads. We have cut that in half over the last couple of years, but there is a ways to go.

The extra bit of possibly using solar for some of this is frosting on the cake! And a lot more Math and $$$.

 

[MisterSandals]

And a lot more Math and $$$.

The biggest and best number to get is the watt hours per day. Then largest AC load(s) running simultaneously.

 

[Shimmy]

Expecting a whole-house UPS can lead to disappointment if you want to do it for everything with a single, combined function, unit. You don't necessarily want compressors starting on your power supply for the computer as an example. There is also the issue of maintaining things where having a UPS close to the load is a huge benefit.

For me, I have a few classes of loads that I want on no-break power: computers/home server/networking equipment, monitoring equipment, and Sonos/TV. Those loads can easily be accommodated on a 1,000W inverter, an if I want to be extra protected I can put a downstream fast transfer switch at the more critical loads. Sonos is only on battery because the system needs to power up in a specific sequence to operate properly, which takes about 20 minutes to do manually each time we lose power.

 

[MillAlien]

I think the OP said “whole house” but it sounds like it’s more about certain critical loads.

He also mentioned a discontinued transfer switch, so switching the inverter system into the “whole house” might not be too complicated and he can manually isolate critical loads by flipping switches at the main panel. Not ideal. (Our “critical load”, apparently, is the wifi router as far as the household is concerned. I added the well pump and fridge because I‘d rather eat than tweet.)

As is the case with many people on this forum, I have a dedicated critical load sub-panel that’s fed by inverters with internal and programmable bypass relays, but my house wiring was configured (by me) to allow for that decades ago. There’s a bunch of ways to reconfigure an existing wiring system to spilt out circuits in ways that weren‘t around then, so it’s hardly and insurmountable problem (although I’m not a big fan of the main switch lock-out route.)

The peak load is one thing, he also needs to decide what he wants for reserve capacity and charging cycle & method. I’m not sure if the energy audit tool does that too. I did all the math in this myself.

 

[Delmar]

I think the OP said “whole house” but it sounds like it’s more about certain critical loads.

Agreed, those are a contradiction in terms. Also agreed with adding a critical loads panel, and incrementally move circuits as the system grows with battery and solar capacity. I would start with an “all-in-one” solar charger inverter that has UPS capability: