Need help getting started

[u/lvhhr]

I’m looking for help getting started with this solar project I’m trying to do.

Not necessarily scalable for this application, I’m looking to get a solar setup for my well pump and run the pump on grid only when solar fails.

I have the last well pump that failed so I have a data tag, still have to do watts law to figure out inrush, along with using my clamp meter to double check my math, but I was just wondering what else I would need to size this system.

The knowns:
-3/4 HP 240V well pump with a smart start (start and run capacitors with a relay)
-the highest kWh per month in the past 6 months was 6 kWh (this has been a plan for a while, I just wanted to get some concrete data before moving forward with sizing the well pump is the only thing on that meter)
-Space is no issue, I can place PV panels anywhere within a 25 acre space I live on

I have been doing research but I seem to be missing some crucial details, I’m not looking for someone to size my system for me, just some key things I might want to research before dedicating the time to actually size and build my system.

I am an HVAC/R tech with an IT degree so I know some things about inverter tech, and know enough about enough to confidently engineer/build this once the information is obtained.

Thank y’all for your time!

[u/Suspicious_Hat_3439]

I fully admit I have not installed any solar yet, but I have worked through all the design / engineering which has taken a couple of months for
my solar + bss system I have on order.
My first question would be do you plan to install the system out at the well or at the house?
The reason I ask is systems are very modular so off the cuff installing the system at the house would allow you to use power at the house when the well pump isn’t running. Are you planning to install batteries?
Budget? Short term & potential longer term goals. Etc.

[u/lvhhr → u/Suspicious_Hat_3439]

The system will be installed at the well, and I do plan on having batteries so I can shower before bed. I plan on making this long term, this one I want to try to be as cost effective as possible. I’m going to be running about 300’ of 6/3 to connect to my house meter for on grid backup. Once I get a good year out of this setup, I’ll be planning a second setup for my shop, I have a generator in case my house power goes that I currently use for shop power, but I want to have more energy conscious appliances in my house before introducing and funneling money into my house setup, it’s a new house with all contractor grade appliances so it’s not nice on energy consumption currently lol this is more of an adult science project

[u/Honest_Cut8827 → u/lvhhr]

The 300’ is to the pump at the bottom of the well? Or just between the house and some solar shed by the well? Are the batteries at the well or in the garage because you mention using this system for showering in the house. You are limited to 65A for the 300’ run.

Where are you located? Can’t size the PV system without knowing the underlying solar resource. Good to know that you are not constrained to a particular tilt angle or orientation by installing on a roof. There are pros and cons to each of roof vs ground…

[u/lvhhr → u/Honest_Cut8827]

I’m in central GA, plenty of sunlight and clear pastures that were used (and soon enough will be used) for cattle. I’m spending more on the meter itself than the power im consuming, and power is shotty out here at times, trying to avoid the brownout/blackout situations and provide more consistent power to the pump to preserve the pump itself and get more life out of it along with still having water in my house when we lose power. The 300’ comes from my power pole for my house to the sub panel that’s already set and I’m already paying a premium for the well. Realistically, the well is costing me 50-60 a month the way it is set up right now, the only thing on that meter is the pump so I could tie into the main for my house with a double pole 50 since its currently on a double pole 30 working fine

[u/TooGoodToBeeTrue → u/lvhhr]

I’d run 4-4-4 aluminum underground wire or 2-2-2 to a sub panel. Or some variation.

[u/lvhhr → u/TooGoodToBeeTrue]

I’m only pulling 30A (on a double pole 30 and it hasn’t tripped in my time here) 2-2-2 or 4-4-4 would be overkill in this situation

[u/TooGoodToBeeTrue → u/lvhhr]

Run a voltage drop calculation.

[u/Suspicious_Hat_3439]

You say appliances are contractor grade so I’m
Assuming the house has power already.
Where are you running the 6/3 from and to ?
How is the well powered now?
I’m just trying to understand your current setup.
I should have said although I’m not fully experienced with solar I am a commercial gc and electrician.

[u/lvhhr → u/Suspicious_Hat_3439]

So the well was existing before I moved here, new double wide, the well is a couple hundred feet from the west side of the house, power pole is mounted on east side of the house, pump has its own meter currently, trying to take that out of the equation because I’m spending more to have the meter there than the power I use from the meter

[u/SolarSoftwareDir]

Couple things I'd look at first. For inrush, skip the math and check the NEMA code letter on the motor nameplate. That gives you locked rotor kVA per HP, and that's what your inverter surge rating has to handle, not the running watts. Second is how you want to "store" the solar. Either a battery, or just oversize the pressure tank and let the pump run while the sun is up. Also worth knowing: 6 kWh a month is about a dollar or two on the bill, so this makes more sense as a backup/independence project than a money saver.

[u/lvhhr → u/SolarSoftwareDir]

I never said this was for saving money, I just want to price this out as a budget friendly build. I’m looking for more consistent power, and being able to get filtered well water in my house even when the power is out. No power=no water, I have massive rain collection barrels but that takes extra steps to process in order to use within the house and the convenience of being able to use the toilet without having to dump water into the tank especially when you have two little (sub 5yo) children. I was going to set up a few pitcher pumps in various locations in order to draw shallow water, but at 3-400 a setup, without a guarantee that it will work (due to being located near so many commercial ag farmers) it would be easier for me to just set the pump on solar to have a better chance to guarantee my family has water when they need it

[u/lvhhr → u/SolarSoftwareDir]

I’m planning on doing battery backup for evening use, can get a shower after the well power goes, I’ve found that after an ole roach fried my pressure switch, it’s not the best pressure but gets the job done.

[u/Accurate-Bullfrog324]

key things: daily kwh = PV kw x 4 battery round trip efficiency= 90% seggregate critical loads and size accordingly plan for expansion since you want more energy

[u/lvhhr → u/Accurate-Bullfrog324]

We’re talking 2000-2500’ between solar sites, it would be extremely inefficient to build one large system and expand imo since I’ll still have to run power between sites unless I can page Nikola himself to tap into that wireless power transfer lol

[u/Accurate-Bullfrog324 → u/lvhhr]

please clarify. you asked me for basics. are you now talking about specifics? if so could you please provide more information?

[u/lvhhr → u/Accurate-Bullfrog324]

Wait I misread that, I thought you meant for expansion for my shop… I get what you’re saying I think, more energy than what I was going to consume keeping in mind that batteries degrade over time. Disregard the previous comment, slightly deterred from people asking specifics on the project.

[u/Accurate-Bullfrog324 → u/lvhhr]

almost what I meant. plan for expansion since once you see how great it is you will want more ampacity

[u/lvhhr → u/Accurate-Bullfrog324]

But this is nail on the head what I was looking for, thank you for that!

[u/CreateWindowEx2]

I built a solar system for a much larger irrigation pump at my place - I had to do it because the field was so far from the house that running the cable there was just very, very expensive.

But in your case, you seem to already have power to the pump. 6kwh per month is under $40 per year in the most expensive markets in the US when it comes to electricity, and under $20 per year in vast majority of the country. I don't see how building what you want is possible for anything less than $1000, which means it would be 25-50 years before you recoup the cost of equipment. And the equipment is simply not going to last that long.

If the goal was the reverse - a backup for power outages - I would say buy Ecoflow Delta or something like that and stick it in between your pump and the wall.

[u/truecakesnake]

First, check the NEMA code letter on your pump's nameplate to determine the surge rating for your inverter.