What are the top 5 gotchas for going totally off grid

[Shimmy]

Living in a similar climate and style of house, some of the most important decisions you will make really come down to building materials. Drywall is one example; if you have temperature/humidity cycling in a naturally ventilated house you end up with tape seam cracks.

Likewise, you want to make sure you always manage condensation risk throughout the year. For us we get minor condensation on the wood floors (dampness vs wet), but we have a lot of natural light that drys things out quickly. A slab on grade vs raised wood platform floor is a similar example-- the slab on grade will have very different properties which may be good or bad.

Making some of the wrong material choices ends up costing extra on your energy budget.

 

[wattmatters]

Pool pump Pentair Intelliflo

Yes, any good quality variable speed pump will be way better for both energy and power consumption than a standard single speed unit. They draw less power, and consume way less energy. Mine has a soft start so there is no surge current draw on start up which makes them suitable for off-grid power systems. The other big benefit is they run so much quieter, and when needed you can crank them up for special tasks (filter backwashing etc).

When I ditched our single speed pump for a Hayward VF model, our energy consumption dropped by 6 kWh/day.

 

[629658]

My intelliflo uses 166 watts at 1190 rpm and 30 gpm. 277 watts at 1495 rpm and 39 gpm. Pretty miserly.

 

[Vigo]

So i’m one of those people who is “not qualified” to comment on living off grid since ive only been 100% off grid in a house with no grid connection since May.

But, so far i agree with the general sentiment that its easier and more universally helpful to build a bigger power system than to focus on efficiency. I think the biggest impediment to that is space and whether it’s ‘compatible’ with PV. Hopefully a luxury home doesn’t have much restraint on that.

Another side of ‘going big’ which to me feels like almost a moral imperative, is to not ‘sell’ the concept of off-grid living that’s only practical if you radically alter your lifestyle. I think it’s generally possible to live as if you are ‘on-grid’ with an off-grid system if you build it that way, and even though the cheapest way not to break a machine is to properly train the operator, in the case of our dwellings i think minimizing the extent that a ‘trained operator’ needs to be in the thing for it to stay working, is an important goal. A bigger power system moves that needle.

I’m not anti-efficiency at all but value per dollar generally leans in favor of the bigger power system, ESPECIALLY in the case of existing structures where any efficiency improvements other than appliances are much more expensive to retrofit than to ‘build in’ during new construction.

 

[camelCase]

A custom home in Costa Rica is probably going to be mostly steel framing and use different materials than we are used to in North America. Central America has termites like you wouldn't believe.

 

[toms]

I agree, I have been managing loads for years and the person asking the question is building outside the USA and I stand by my recommendations. LP is readily available and if he installs some LP appliances it will decrease his demand and allow for either some savings if system size or give him some head room so he is not running on the edge. I am in the USA and I am still considering switching my dryer to LP for the same reasons. Personally, if they were readily available, Id consider an LP refrigerator. THey are very efficient and they operate with minimal electrical load. If you were a camper I believe you would have a similar opinion. My recommended pool pump is absolutely spot on.

There’s no such thing as lack of “headroom”. Any full sized residential off grid system (such as the one the OP is enquiring about) will include a fuel powered generator. The only point of interest is the cost of fuel over the lifespan of the system vs the extra cost of the energy efficiency of whatever appliance/building extra you are considering.

A lot of the suggestions here are more suited to a very small building, or mobile application.

 

[Vigo]

Well, that’s another thing to consider, that the ‘payoff timeline’ of an efficiency investment probably doesn’t ‘get worse’ very often. On the other hand, trying to project long-term costs of commodities like fuel is subject to huge unforeseen changes which could make you wish youd done something entirely different. So while you’ve got to have a generator, you probably don’t want it being ysed very much or the long term economics of the system are very much in the wind. But ‘luxury off grid’ is probably not overly concerned about fuel costs anyway.

 

[629658]

I happen to live in a large modern home 4400 sq ft. with all the amenities also a pool and livestock. Been Grid Tied for 8 yrs and just upgraded to an AIO with 900+Ah storage. We also have been camping for 20 yrs. We are totally self contained here with a well and septic system. So we are moderate power users. We have a whole home genset too. We are off grid for 22.5 hrs a day most days. The grid is our backup power source but we could be off grid anytime we wish. I still take opportunities to decrease our consumption through a diversified approach. From our camping days an LP refrigerator works very well and very efficiently and if I could find a home model I’d buy one in a min. I also think if one can reduce their load requirements without much sacrifice it simply makes sense to do so.

 

[Darren67-72]

I hesitate to comment. There are a million factors. My wife and I have been light electricity users most of our lives. Our only luxury is a/c. I mean we don't wash our clothes by hand or anything. But, we live in Michigan and winters bring a little needed attention, nothing more than keeping an eye on storms.
We live in a old farm house and don't have to worry about power all the time, just live and use power as we want. Trying to remember to do more in the middle of the day.
ANYWAY, we had a full size upright fridge, about 13ish cf. Propane. They do make them. Look for a amish community and they will have a "hardware" style store that has them. They even have door lights (they use D batteries) they run about $1200 usd. Remember, they are not frost free. We sold ours because, we don't think a energy star fridge uses that much anyway and, this year we went off LP. That has put a squeeze on the excess watts. Lol

 

[629658]

Well I get it we have 3 refrigerators and a freezer so it can be done but I think an LP fridge has some merit. LP dryer and ovens too. This does 2 things it means you’re not running close to max capacity much and it gives you some room for those cloudy rainy days. It would be extremely expensive to have size big enough and have several days worth of storage. I have just spent 35k on upgrades and did the majority of the work myself. I had an existing array so that doesn’t include any of that. My expenses were primarily AIO, wire and storage. I bet you could drop 100k in a blink if starting from scratch.

 

[Darren67-72]

Again, too many factors. I spent a year doing the math, Seriously. Built the system with 20% head room and it works great. We are good for 2 days poor solar (that means 3 nights, some people don't get that part) then its genny time. We have only used the generator 4 days this year. Not bad, but we still have better than a month to go.

 

[wattmatters]

My intelliflo uses 166 watts at 1190 rpm and 30 gpm. 277 watts at 1495 rpm and 39 gpm. Pretty miserly.

This is mine. I don't run it as slowly as yours, I'm now running at 1900 rpm and ~320 W.
50,000 litre pool in a warm to hot climate.

 

[629658]

This is mine. I don't run it as slowly as yours, I'm now running at 1900 rpm and ~320 W.
50,000 litre pool in a warm to hot climate.

I like your graph. I did the same thing. I ran it through the speeds checked current and flow. I found 2 sweet spots. I love the intelliflo stuff. It’s pricy but great. We have the intellichlor salt system too. We run approximately 3 four hour cycles. Sometimes more sometimes less.

 

[Hedges]

Mine had a 3600 RPM single-speed 2 HP pump. I replaced that with 2-speed, but as DE filter gets loaded too little flow at 1800 RPM.
Now with VFD and 3-phase motor I probably run half way between. I turn the speed up until it makes noises (cavitation?) which occurs with fresh filter media or inlet restriction due to pool vac hose, then back off. Running at full speed on a hot day it draws enough current to trip 20A breaker, so much more power than you guys are seeing.

I don't find "Power Factor" in the specs or manuals

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/manuals/pool-pumps/intelliflo-vsf/intelliflo-vsf-om-eng.pdf

This model is 3.2kW at full load.

(By the way, manual mentions that certain models don't include the entrapment protection system, something you might look for. It detects blockage on inlet like a person sucked against intake and shuts off, to reduce drowning hazard.)

This manual says "Active Power Factor Correction"

Power Factor can matter for some inverters. My system is AC coupled, so PV inverters check AC waveform before connecting. My VFD has basic capacitor/rectifier front end which distorts waveform and upsets the inverters. Probably not a problem for DC coupled or AIO systems, which don't monitor grid before operating. Hopefully the PFC in these Intelliflo work well.

 

[629658]

I don’t have the entrapment feature code here is double main drains at least 6 feet apart.

 

[Hedges]

Yes, I think newer pools would be built that way.
You can also have an inlet cover that is raised, with gaps all around the sides, instead of a flat grill.
Probably entrapment protection is more important for a pool with single inlet.

I've read of such incidents only rarely. If microprocessor controlled pump can detect that reliably, might be a good thing.
I can imagine how difficult it is to validate such a design.

No good deed goes unpunished? Cars have ABS, and some detect a flat tire by different rotational speed. I read recently of a recall because a car's system would not detect flat tires if all four gradually lost pressure about equally. I could imagine liability issues for a company that marketed a pump as having entrapment protection.

 

[wattmatters]

We run approximately 3 four hour cycles. Sometimes more sometimes less.

I just run one duty cycle/day. It is automated via Home Assistant and I have various layers of control.

There is a minimum run time each day, and a maximum run time each day. It adjusts the duty cycle between those limits based on the length of day (uses offsets to Sunrise and Sunset), so that duty cycle constantly varies through the year, i.e. longer in Summer, shorter in Winter. It also delays the start time until solar PV output is sufficient to power the pump, at least until the minimum run time start is reached.

 

[629658]

Now that’s cool. I use the Pentair screen logic setup. It controls the lights, SWG and the pump. I haven’t got into Home assistant yet but it looks like I’m about to.

 

[wattmatters]

Yeah in Winter it was drawing ~ 1.5 kWh/day, while at present (late Spring) it's drawing ~2.5 kWh/day.

 

[629658]

So I have thought about getting another Pi and playing around with HA. Can you integrate multiple things like my Solar and Pool? I wonder if it will communicate with my Pentair stuff?