Can I use grid-tie solar to run a well pump during the day during a power outage?

[MichaelK!]

For my own system, used in pumping water, I'm using L-16s. Basicly, the system I've described above is exactly what I'm now using to pump water. I have no working experience with Lithium at all.

The running characteristics of my pump closely track the numbers that Mike90250 posted above. My 1hp Grunfos pump has a running amperage of 9.5A, with a startup surge of 37-38A. It was very interesting to observe that the XW produces cleaner power than my generator does. Under exactly the same conditions, my pump draws 10.0A and pumps 275 gallons/hour. Powered by the XW, the pump draws 9.5A and pumps 325 gallons/hour.

[Ampster]

Just curious, would Li-x batteries be better to provide the surge watts required to start loads like well pumps?

Some varieties of Lithium are capable of rates of 10 times their capacity for short bursts without much voltage sag. . That is why they are used in EVs. They are also more efficient but there are tradeoffs that you need to become informed about.
Read the sticky threads about charging them. Stay away from LIPO packs like the ones used in RC Helicoptors.which can have C rates in excess of 10C.

[Mike90250]

The XW series of inverters, have transfer switches internally, so that expense can be deleted. And they have a 2nd input for your generator, so it's all set to go.

[solardreamer]

For my own system, used in pumping water, I'm using L-16s. Basicly, the system I've described above is exactly what I'm now using to pump water. I have no working experience with Lithium at all.

The running characteristics of my pump closely track the numbers that Mike90250 posted above. My 1hp Grunfos pump has a running amperage of 9.5A, with a startup surge of 37-38A. It was very interesting to observe that the XW produces cleaner power than my generator does. Under exactly the same conditions, my pump draws 10.0A and pumps 275 gallons/hour. Powered by the XW, the pump draws 9.5A and pumps 325 gallons/hour.

If your generator is not an inverter generator then your observation makes sense since XW is a pure sine wave inverter. Otherwise, it seems a bit odd.

[Ben94122]

An update: August of 2020 we had a company install an 8.5kW roof-mounted solar array with an LG 9.6 kWh battery and a StorEdge inverter. The solar array runs the well pump, freezers, internet, and charges the Tesla (slowly) with no problems. We had a busy summer for wildfires, with multiple power cuts and a 3-week evacuation. The system ran the sprinklers and freezer as described above, with no issues. The well is 350' deep.

Take the naysayers on this forum with a grain of salt.

[oregon_phil]

Interesting. In your original post, I thought you didn't want a large expensive battery?

Do you have your well pump, etc. connected to a separate backup load electrical panel? The StorEdge is rated Max AC Power Output - Surge: 7000 Watts for 10 seconds. It would be interesting to know what your backup panel voltage/current curve looks like when your pump starts up.

Do you have a VFD pump or standard 40/60 pump system? just curious.

[Ben94122]

I priced a backup generator, and it was more expensive than the battery for the installation cost, even without taking fuel costs into consideration. California also offers incentives for the battery installation, but not in my area. It's called SGIP, for those who might be interested. Also, since the battery was part of the solar installation it qualified for the federal tax rebate.

We do have the backup loads in a separate panel. 4 x 20A breakers, and the well is on a 240V x 20A breaker. I emailed the manufacturer of the inverter (SolarEdge) and asked them specifically about the well. They told me it was no problem. I don't know exactly what the well startup current is, but it's not enough to trip a 20A breaker. It doesn't show up as a spike on the consumption graph provided by the inverter.

I don't know the details of the well pump. I could look for the paperwork when I get home if you are interested.

[Mike90250]

So.... you must be looking at some whole house size, automatic generator. $ $ $ $ $

Is your inverter capable of backfeeding the battery to recharge it from the generator, if the weather is bad ?

Have you considered a temporary backup generator, in the 5-8 Kw size, to keep only the basics running ? With the battery you have, you should have enough time to decide if the generator is needed to run, and manually start it and plug it in.

[azdave]

Take the naysayers on this forum with a grain of salt.

That's funny. Adding a large backup battery to your system completely changed what you were asking for in your original posts. Folks here gave solid advise within the parameters you insisted should work. You eventually found a solution which included a large backup battery and it's been working out great for you. Awesome! Pretty much what solarix told you in the very first reply.

[Mike90250]

Me running my generator at 1pm, with fires 100 miles away. Really consider needing a generator when your panels are blacked out,
The lights in the shed are 4W 120V LED's




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[oregon_phil]

I agree with Mike. Here's my 10.22kW system output September 2020 with a wildfire 10 miles away blowing ash everywhere. This went on for 10 days. Then February 2021 our power went out for 12 days due to an ice storm. Solar was nil in both cases. That's why I went with a NG generator instead of batteries.

[v10tdi]

FWIW...

A couple of years ago I acquired an 8.4kW solar with 9.8kWh LG battery backup to help with our home in NC mountains...specifically needed to ensure that we had refrigeration, internet, (LED) lights and well pump. I knew that existing well pump (450' well) was going to draw more startup power than the battery would sustain (even without the other loads), so I replaced it with a Grundfos pump that had a 2A startup draw and peaked at 13A (rather than 27+A startup draw). That enabled me to swap out the 30A (240V) breaker for a 15A breaker on that circuit.

Fast forward to 2021...TS Fred dumped 12" of water in a matter of hours...bad news in the mountains: road was out for 4 days, no power, no internet and the cell phone tower (which hardly works on a good day) was having issues.

Solar/Battery system functioned exactly as we needed...BUT we had enough sunshine during the days to run all the backup systems and recharge the battery. 5+ days of fires/smoke/clouds are not factors that we needed to consider likely for our location. That said, we do have a 7kW generator (and fuel) in reserve for outlier conditions.

The one thing we are evaluating is our hot water. We used our gas stove (500g propane tank) to heat water for dishes, coffee, etc. but by day 4 our hot water heater was running only warm-ish for showers. So one of the things I'm considering is either converting to gas HW (propane) OR an electric A/B switch (i.e., like on a boat, ship/shore power) on the electric water heater to engage the solar (during the day, not battery) to heat up water. Existing electric HW tank is 6 years old, so I'm inclined to go with the A/B option rather than branching off the propane line and swapping out the HW heater.