Hello from the California central coast.

[thewilliam]

Recently acquired some Solar stuff from an estate. I've already read a lot and could set it up to power my pool equipment this weekend for an experiment. - maybe a 1kw load.

It's probably a bit undersized for my house, it was originally intended for a garage/shop.

Just trying to figure out what to do - how best to use it. I've downloaded the last three years of hourly usage from my utility - this past , HOT, summer there were maybe 30 days where usage exceeded 2500 watts in any given hour - that will be my hvac load - noon to sometimes 2100, my house stucco and attic really holds the heat. I don't have a feel for instantaneous peaks.

TIA for the help.

12 ea CS1Y 400MS panels, 48v 400 watt
2 Eco-worthy 6 string combiners
1 Growatt SPF 5000TL parallel option
1 Growatt 5000 ES - the grounded-neutral version
One 5 kwh Terli battery Helio 5
Some mounting clips
No racks, definitely going to need more mounting hardware.

Hourly usage stats for last three years :

• 85% less than 2 kW
• 9% between 2 and 3 kW
• 5% greater than 3 kW

Between hours of 0600 and 2200

• 8% greater than 3 kW
• 79% less than 2 kW

Number of times an hour exceeded 4500 Watts

TIME --- number
1000 --- 6
1100 --- 29
1200 --- 57
1300 --- 86
1400 --- 115
1500 --- 120
1600 --- 126
1700 --- 94
1800 --- 68
1900 --- 33
2000 --- 18
2100 --- 8
2200 --- 2

 

[Risky Rob]

I have an even smaller system. The panels are on the roof of a shed. I have wired the inverter to a house outlet, but plan to make a connection to the house panel. It's not full time, whole house power, but enough to run things like a gas furnace and refrigerator in an emergency.

 

[Hedges]

230V inverter?
Will you have grid or generator input to it?

Maybe connecting output to a 120/240V auto-transformer would be the thing to do, if you want to power some 120V loads. For 240V loads, typical household breakers rated 120/240V are only 120V per pole, so feeding them through a separate breaker panel with one pole for 230V and one pole for neutral would be a way to have ganged 2-pole breaker operate within its ratings.

Of course 240V to 120/240V isolation transformer could also be used. So far the transformers I'm playing with draw higher no-load current than I'd like. A disconnect feeding step-down transformer could let you remove that standby load when 120V loads are needed.

When I measure no-load current of transformer with an oscilloscope, I see current peaking every cycle, not a sine wave. That indicates to me it is driven part way into saturation, and inverter has to provide that current. Current is out of phase with voltage so energy could be recovered if inverter is able to deal with that.



If you got a 240/480V to 120/240V transformer, and used the 240/480 windings as auto-transformer for 115/230, I think that would avoid the current peaks (because windings operated at half their rated voltage.) It would be good for the the rated current of those windings.

What I haven't looked into yet is power display of inverter, or battery current, when driving transformer. That could distinguish power loss from the "power factor" of out of phase current, which may be recovered by inverter.

 

[thewilliam]

230V inverter?
Will you have grid or generator input to it?

230 volt inverter. I won't have a generator.

One question I haven't looked for yet: I know the inverter will use both solar and the battery at the same time if it needs to, but if those sources are not sufficient the inverter just switches to the utility and it won't use either of those DC inputs. I'll ask that in a different post.

 

[Hedges]

So inverter will have utility grid available, and will switch to that?
In that case you'll have the issue of how L1/L2/N/G of the grid should connect to L/N/G of the inverter, and how that should connect to your loads.
There are threads on that topic and a bunch of us poking holes in a vendor's schematic.
The most robust/safe/compliant solution would be isolation transformer between 240V L1/L2 of utility and 230V L/N of inverter input, and isolation transformer between 230V L/N output of inverter and 120/240V L1/L2/N of your loads.
But you may come up with an adequate alternate configuration.