Future Off-grid plans - help!

[WyoRick]

We will be building a tiny house off-grid soon and I need to design the solar power for it. Our current consumption averages around 18 kwhr / day and I anticipate it will remain the same or go down. Besides the normal household, refrigerator/freezer, chest freezer, washer, gas dryer, etc. I will need to power a deep well.

I am looking at a Growatt in either 24 or 48 V, 250W panels and LifePO4 batteries. I like BigBattery.

We live in Wyoming and get 3.3 sun hours in the winter.

I'm looking for recommendations for the build on the items above. Single or double Growatt, how many panels and how much battery (GRILA?).

Thanks,

Rick

 

[snoobler]

Welcome to the forum.

In addition to the 3.3hr in winter, Link #5 in my signature to determine your available solar.

Helpful to break usage down into monthly kWh numbers to compare to available solar numbers to find your "worst case."

The deep well is the kicker. They tend to have HUGE surge currents that Growatt high frequency inverters can't handle.

Using the best info so far.

18kWh / .85 (inverter efficiency) = 21.2kWh/day usage.

21.2kWh/3.3h = 6.4kW of solar panels, and you'll need about 21.2kWh of battery storage for each day you want to be able to go without charging.

 

[Steve_S]

We will be building a tiny house off-grid soon and I need to design the solar power for it. Our current consumption averages around 18 kwhr / day and I anticipate it will remain the same or go down. Besides the normal household, refrigerator/freezer, chest freezer, washer, gas dryer, etc. I will need to power a deep well.

I am looking at a Growatt in either 24 or 48 V, 250W panels and LifePO4 batteries. I like BigBattery.

We live in Wyoming and get 3.3 sun hours in the winter.

I'm looking for recommendations for the build on the items above. Single or double Growatt, how many panels and how much battery (GRILA?).

Thanks,

Rick

You will really need to do a proper usage estimate.
I run my place on 4kWh a day, have a deep well pump @ 260' down then to 50 Gal pressure tank then 75' to house. 120V Soft-Start Grundfos SQ-5 pump. I use an Energy Star Rated Fridge which uses 247kWh per year.
Radiant Heating in floor using an independent On-Demand Water Heater (but using glycol) and another On-Demand for Hot Water + Unique Offgrid LPG Cookstove, of course all LPG fueled.

Your appliances / devices should be measured & calculated for energy use using a Kill-A-Watt type meter. The TRUTH is that it is far cheaper to conserve than to Generate & Store energy. Things like Water Pumps MANY people trip all over and have a ridiculous belief that you have to have 240V for a Water pump. Case in point, mine starts pushing water at 550W and stages up in 150W increments, by the time it reaches 50PSI and pressure tank is full it is only pulling 1100W off 120VAC circuit... 260' deep + 75' to house is the water run length. Fridges & Freezers CAN be nasty, grandma's fridge that you inherited which was made in the 1960's may work great but it's an energy pig. The latest proper Energy Start rated appliances can be very efficient. BTW: I am using A Danby brand fridge, they also own the Magic Chef Label and they are not crazy expensive either.

Have a look at the link in my signature "About my System" for more details and info. Feel free to ask questions, there is no such thing as a stupid question , except for the one not asked. There are quite a few Cabineers and Off-gridders lurking here and some of us are far more North than you and doing it without issues and many lessons learned too.

 

[WyoRick]

Thank you both for your inputs. I can't afford to go solar on what I consume now so we need to plan to conserve. No appliances are bought yet so obviously energy conserving will be needed there and propane where possible. The soft-start pump is a great idea. I was looking into that for the A/C on my camper.

So using the the parameters I originally listed but using only 4-5 kwhr / day, what equipment would you recommend?

 

[snoobler]

5kWh/3.3hr = 1500W of panels - $360 + shipping from SanTan Solar (8 240W panels).

7kWh of DIY LFP cells + BMS - $1100

24V inverter capable of delivering your power/ needs, $1800. I'd look at the Magnum MS4024PAE for 120/240V split phase if you need it. If your pump surge is beyond that, I'd look at a Sigineer 5kW/24V split phase unit... crazy high surge, but you pay for it via reduced efficiency, and they're cheaper at around $1000.

EDIT: 60A charge controller $400

Misc wiring, etc., $500

 

[Steve_S]

Thank you both for your inputs. I can't afford to go solar on what I consume now so we need to plan to conserve. No appliances are bought yet so obviously energy conserving will be needed there and propane where possible. The soft-start pump is a great idea. I was looking into that for the A/C on my camper.

So using the the parameters I originally listed but using only 4-5 kwhr / day, what equipment would you recommend?

Well that is also a Budget Issue.
My Inverter/Charger is 2 Grand and SCC (Solar Charge Controller) is 1 Grand. But it's all Tier-1 level stuff because I must be able to depend on it.
IF I was building "today" I'd likely go with all Victron Equipment (was not available when I built my system).
IF Budget was a driving consideration, I'd look at SolArk, Growatt then MPPSolar AIO's (All in Ones) which have come a long way. The order is the preference for quality but also high cost to lower cost.

If I wanted to keep to more better "Value" oriented due to lower budget, I would look towards EP-Ever and their equipment can be interconnected (they also have Inverter/Chargers besides SCC's.

Always avoid tier-3 "Value Gear" like Renogy which spend more on promo than product quality or support.

I guess you did not look at my "About my System" page. I am running at the moment with 910AH of LFP (21.9kWh) as my primary bank and with 956AH of Heavy Lead (21.3kWh gross) which is now my backup bank. The system is 24V, the Inverter is 95% efficient (value ones do not get much higher than 88% efficient).

Well Pumps, Mini-split AC/Heat and such are available with "Soft Start" but you have to shop for that in the spec.
Grundfos are not cheap pumps but when you buy one it will last 20 years+. It's not something you want troubles with and so worth spending on it.

 

[MichaelK]

I can give you the specs of my system, that does run my submerged 240VAC well pump, and does produce 20+kWh per day.

I have 15 72-cell 300W panels in five arrays. That's 3S5P
I have a Midnight 200 charge controller
Schneider XW+ 6848 inverter
eight Trojan L-16 batteries wired for a 48V system.

I only use 20kWh a day while pumping irrigation water out of the well. On regular days my consumption is more like 3kWh, and about 8kWh in the summer when I run the air-con.

I have to agree that you need to do a detailed audit of your power consumption, and I think there's likely a lot of power that can be saved there, but the system as described above will accomplish the preliminary goals you are stating.