What are the top 5 gotchas for going totally off grid

[toms]

I don't agree with this, save the energy so you don't have to create it in the first place.

Show me the numbers. I’ve been through dozens of actual installs, and it’s only edge cases where spending dollars on extra efficiency beats spending dollars on your power system.

How long have you lived off-grid, and what is your average daily usage?

A good example of this is a neighbour if mine that spent close to 100k extra on building a passivhaus spec home.

He still had to build a power system, and still had to install RC aircon for those stretches where we get over 40°C days for weeks on end.

An extra 20k on his power system instead would have enabled his house to sit precisely at his desired temp/humidity for his lifetime.

For sure hit the easy targets like insulation and sensible design - but things like ultra efficient appliances, or expensive building modifications will not pay off in most cases. It’s one of the most common mistakes i see when people go “off grid” and rely on advice from experts who don’t actually have a lot of experience with off grid life.

 

[wattmatters]

Have data cable outlets everywhere and a data management centre/switch box. If you plan to make a home smart with automations and manage energy systems, having the reliability of data cables is hard to beat.

 

[Bigbeam]

I lived on a catamaran for 3 years in the Caribbean 2009 to 2012. By far the biggest issue for us was refrigeration as this was 95% of our daily energy consumption. We were running dual danfoss 12v compressors to run separate fridge and freezer. By today's standards our system was crude: 1200 amp hour lead acid batteries (12 golf cart bat's) 500w solar and 6kw genset. We had to do 1 hour of gen time everyday. We also had 40gph (gal per hour) 110v water maker which had to run off genset (3kw inverter couldn't run the 2hp motor). We averaged 100 gals water per week for family of 3 all taking navy shower daily and we had washing machine on board as well. Toilets were salt water so huge water savings there. Genset burned 0.75 gph diesel so ~8-10 gals a week. We never stayed in marinas, always on the hook. Was pretty shocking coming back to land to how much water and energy we waste and how much its taken for granted.
Skip forward to today and you see cats with 3kw solar, 1000ah+ Lithium, no genset running A/C and net zero energy. Watermaker will be 12v low gph that you run longer. These are spendy installs (everything marinized) but also saving $20k foregoing the genset. As always, it works when you have the sun and big enough bank to get through weather days (maybe without ac though). Refrigeration and ac will be your big consumers so focus on that. I would also lurk on some of the sailing forums to see what the cruisers are doing (cruisers forum.com)
Cheers
Kevin

 

[jameshowison]

Show me the numbers. I’ve been through dozens of actual installs, and it’s only edge cases where spending dollars on extra efficiency beats spending dollars on your power system.

How long have you lived off-grid, and what is your average daily usage?

A good example of this is a neighbour if mine that spent close to 100k extra on building a passivhaus spec home.

He still had to build a power system, and still had to install RC aircon for those stretches where we get over 40°C days for weeks on end.

An extra 20k on his power system instead would have enabled his house to sit precisely at his desired temp/humidity for his lifetime.

For sure hit the easy targets like insulation and sensible design - but things like ultra efficient appliances, or expensive building modifications will not pay off in most cases. It’s one of the most common mistakes i see when people go “off grid” and rely on advice from experts who don’t actually have a lot of experience with off grid life.

Show me the numbers. I’ve been through dozens of actual installs, and it’s only edge cases where spending dollars on extra efficiency beats spending dollars on your power system.

How long have you lived off-grid, and what is your average daily usage?

A good example of this is a neighbour if mine that spent close to 100k extra on building a passivhaus spec home.

He still had to build a power system, and still had to install RC aircon for those stretches where we get over 40°C days for weeks on end.

An extra 20k on his power system instead would have enabled his house to sit precisely at his desired temp/humidity for his lifetime.

For sure hit the easy targets like insulation and sensible design - but things like ultra efficient appliances, or expensive building modifications will not pay off in most cases. It’s one of the most common mistakes i see when people go “off grid” and rely on advice from experts who don’t actually have a lot of experience with off grid life.

Well insulated houses maintain consistent internal surface temperatures. Meaning no hot/cold spots on walls, windows, ceilings.

Even the most expensive HVAC machinery cannot do that. They can fight it with cooled/heated air but the temp diffs remain (you have to overheat/cool the air to affect the surfaces.

The Concept of Mean Radiant Temperature Is Key to Understanding Comfort

Design editor Lloyd Alter discusses a blog post that he says is one of the most important posts on building science that he has ever read.

www.treehugger.com

 

[jameshowison]

And more relevant to this build, which seems to be in some Goldilocks zone

Consider ducted whole house vented dehumidifier. Amazing how much closer people’s temperature comfort range is with humidity managed independently from temperature.

Also think about speed of hot water arrival at fixtures. That either means a centrally located tank, with a large loop and small, short branches to each fixture (maybe with demand recirculating in the large loop). Avoid the single large manifold design at all costs

Or it means lots of local inline electric water heaters, sized just for the fixture. That design works better for sprawling single story house designs.

Faster Hot Water Can Change Your Life - Energy Vanguard

We’ve normalized the abnormal in our homes in so many ways that most people have no idea what kind of performance they should expect. If you’ve never lived in a house with a good building enclosure and HVAC systems, for…

www.energyvanguard.com

And home performance YouTube might be interesting as well.

You might enjoy this book, just published:

Book: A House Needs to Breathe...Or Does It? - Energy Vanguard

www.energyvanguard.com

 

[toms]

Well insulated houses maintain consistent internal surface temperatures. Meaning no hot/cold spots on walls, windows, ceilings.

Even the most expensive HVAC machinery cannot do that. They can fight it with cooled/heated air but the temp diffs remain (you have to overheat/cool the air to affect the surfaces.

The Concept of Mean Radiant Temperature Is Key to Understanding Comfort

Design editor Lloyd Alter discusses a blog post that he says is one of the most important posts on building science that he has ever read.

www.treehugger.com

Sure, but insulation has diminishing returns.
The last 5% of comfort will cost 95% of the budget. Leave it at 95% and spend the rest on your power system.

When it’s 50°C and in the full sunlight, how much do you think a window that will remain at less than 25°C on its internal surface would cost?

 

[Quattrohead]

Sure, but insulation has diminishing returns.
The last 5% of comfort will cost 95% of the budget. Leave it at 95% and spend the rest on your power system.

When it’s 50°C and in the full sunlight, how much do you think a window that will remain at less than 25°C on its internal surface would cost?

If you take the typical build quality of a standard American house it is pretty awful with very little care and attention made to sealing air infiltration gaps etc.
Windows installed by builders scrape the bare minimum standards in the USA and no standards are nothing to write home about. The windows that the rest of the world get are probably 10 times better than the cheap nasty ones that are fitted to the vast majority of USA home.
Fiberglass insulation is an embarrassment to the insulation industry it is so inadequate. Spray foam insulation is the gold standard and makes such a difference to the building envelope both in terms of insulation and strength.
A little time and effort and better quality materials will make a huge difference and is well worth the money spent over just throwing Watts at the problem.

 

[Hedges]

Fiberglass insulation is good enough that with studs 16" on centers, half of heat loss is through the studs.
Any better insulation than that (between studs) offers diminishing returns.
Need some other configuration of insulation to improve - staggered double row of studs? Sheet insulation over the wall (over sheathing for better insulation, or under which would compromise strength)?

Have a drawing of where the spray foam goes?

 

[OffGridForGood]

half of heat loss is through the studs

Typical heat losses 33% to 50% through Framing - not just studs - since no matter what stud-arrangements are used, a lot of the wall area is top and bottom plates and headers/trimmers/jacks around openings.
Full exterior layer of sheet insulation outboard of the sheathing makes a big difference to this thermal bridging.
To the point: it is not necessarily a lot more $ to do improved thermal design, if planned from the start.
Retrofitting is harder/more expensive.

 

[629658]

I’m building a house from the ground up in Costa Rica which will be off grid with grid back up. I’m going to do a very high-quality system with basically all Victron maybe even Victron batteries as I am Victron dealer and get good pricing.

I have every choice in front of me for how the house is built and wired, voltages used, what appliances are chosen, light fixtures etc. I’m working on a load spreadsheet ans PDR I have some data from my current home there and some other similar homes. The home will be a luxury jungle villa at 1,500 ft elevation - very open to nature w/ very little HVAC needed but some storage spaces will be
dehumidified and we will put mini splits in the 4 bedrooms just in case someone has to knock down the humidity to sleep. I’m not asking for specific system design advice but rather general pitfalls.

What are the things that people don’t think about ahead of time that come up later or those things that “if I had it to do over again” .

For example there was recently a thread about a high efficiency front load washer that had inrush spikes back and forth due to the way the motor reverses. I would never have thought to consider this type of machine a special challenge for off grid.

Cook with induction or propane?
Passive rooftop water heater or several small instant heaters?
Pool pump choice/programming?
Lighting?
Smart home stuff?
Frig/freezer choices?

Propane for dryer and cooktop. Pool pump Pentair Intelliflo, if I were off grid I’d probably consider an LP refrigerator too

 

[upnorthandpersonal]

A modern refrigerator should be very energy efficient. Mine (fridge + freezer) consumes well under 0.5kWh per day. Do a power audit and get a proper idea of the loads. My place is in a cold climate, so not all of the info I mention on there will be relevant to you, but maybe some of it might be.

 

[wattmatters]

I have power monitoring on two fridges. Standard upright, single door fridges, with a lower separate freezer compartment.

Over the last 40 days, on average:
The larger one uses 1.46 kWh/day (60.8 W average)
The smaller one 1.05 kWh/day (43.8 W average)

We are a warm to hot climate.

 

[Quattrohead]

My 15yr old garage beer fridge was consuming around 2.8kwh per day in the height of summer and now in November around 1.5kwh.
The garage could hit 90f in the summer and it seemed like the fridge was always running.
I have added a fan to the radiator on the back to assist cooling it and that seems to have made a 0.5kwh/d difference too.
During the summer this fridge was the second highest consumer of electricity after the house AC !!!

 

[toms]

Propane for dryer and cooktop. Pool pump Pentair Intelliflo, if I were off grid I’d probably consider an LP refrigerator too

Good answer for ten years ago. Like so many theorists, it would be wise to actually live off grid for a while in a variety of different scenarios before offering advice.

Seriously, just build your off-grid house exactly the same as you would build a grid-connected house. Then install a power system to suit your new house.

There is no reason to do anything differently because of your power supply method.

 

[Quattrohead]

Fiberglass insulation is good enough that with studs 16" on centers, half of heat loss is through the studs.
Any better insulation than that (between studs) offers diminishing returns.
Need some other configuration of insulation to improve - staggered double row of studs? Sheet insulation over the wall (over sheathing for better insulation, or under which would compromise strength)?

Have a drawing of where the spray foam goes?

I am building with 6" ICF walls and 2" closed cell with 4" open cell over it under the roof deck so best of both worlds.
I will have to introduce controlled leakage into this home with an ERV because it will be so tight.

 

[Quattrohead]

Seriously, just build your off-grid house exactly the same as you would build a grid-connected house.

Good advice anyway as energy cost's are going up no matter what.

 

[upnorthandpersonal]

Seriously, just build your off-grid house exactly the same as you would build a grid-connected house. Then install a power system to suit your new house.

There is no reason to do anything differently because of your power supply method.

For the most part, I agree. The caveat being that you do have to keep certain special cases in mind - I generated 0.3kWh yesterday from a 10kW array...

 

[Hedges]

There is no reason to do anything differently because of your power supply method.

Except, if your power supply is not bottomless, implement load control.
You might want to disable some loads based on SoC, enable some as "dump loads" when there is excess production.

 

[629658]

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.

 

[Hedges]

Dual energy source would be useful.
There are heat-pump water heaters with backup resistance heating. Haven't seen backup gas, which would be better.
Some version of gas + electric would let you consume surplus PV and save gas, maybe electric water heater for pre-heat before gas.

I have central gas furnace, and added an electric resistance duct heater to burn off net-metering credits. (horribly impractical for off-grid of course, would use gas when grid down.)

I think people with RVs have been installing efficient AC powered refrigerators, a good fit for larger PV systems.