Feast or Famine, The off grid solar dilemma.

[EastTexCowboy]

Same. I've lived in the States for a few years; I still don't understand why everything needs to be so much bigger. Even with my family of four, I've never thought "if only we had a larger washer/dryer". Or bigger house for that matter: what do you do with all that space? Never mind the energy requirements...

A large part of it is just the culture that has developed here, really since WWII. Bigger, better, faster, newer. I agree 100% with @MattB on the larger washer and dryer. There are only two of us and my wife loves her jumbo W&D. Washing large items like comforters is easy. But her thing is she only has to do a few loads a week. Efficiency wise it may actually same money and water.

We're guilty of the large house sin but it was part of the package when we bought the place and everything else was perfect. That said, we were going to build before we found this place and I would have built something almost as big. Resale is definitely part of it. I think part of it is because we Americans need a lot of room just to store all our stuff! Ugh. We tossed a lot of "stuff" when we moved and we still have way too much. But if you really want to look at signs of excess, look at the gazillion self storage units in this country. Half the new construction around here seems to be more and more mini storage units. I've never been guilty of paying rent on a place just to store more junk. I get it when you're in the middle of a move or some other valid reason but I've known countless people who have one or more units they rent for years and years. Just to store their stuff. The rent often costs more than the stuff is worth. Is this an American phenomenon or do y'all see it elsewhere too?

 

[upnorthandpersonal]

y'all see it elsewhere too?

Very difficult to find 'storage boxes' over here. When I lived in Texas I remember seeing them everywhere...

 

[OffGridForGood]

Once you have a system set up, It becomes a Vicious cycle:
Step 1 -adding more PV to get through poor days, leads to
Step 2 -adding more battery to have somewhere for excess solar on good PV days, leads to
Step 3 -adding more loads since the larger overall system can now handle them, until a few rainy days in a row,...leads to -repeat from step one.

Our dump load options:
1. Run around turning on things, welding something and generally doing some stuff that I put off on some rainny day.
2. A spare electric HWT controlled via I-phone app.
3. EV charging. (to me, the EV costs about 4-cents a mile for "fuel" if we charge off-peak using grid, compared with an ICE-car that is 24-cents per mile for gasoline. Getting some solar charging to the EV is just icing on the cake, rather than to lose that solar potential, even if only during spring/summer.)

 

[SilverbackMP]

I just want to live like 18th century trumped up Yeoman complete with manor house. I say Yeoman rather than landed gentry as I like working with my hands and equipment. Is that too much to ask?

 

[Hedges]

Or bigger house for that matter: what do you do with all that space? Never mind the energy requirements...

A smaller house has higher ratio of surface area to volume, and that is where thermal energy gets lost.
How can you stand being so inefficient?

(Same goes for body size as well, and I am the shrew)

 

[Mattb4]

Today is shaping up to be a solar feast! Beautiful sunny morning not a cloud anywhere. Should be able to have my batteries charged by 1pm and can devote the rest of the day to heating water. Be great for my annual shower (whether I need it or not) to have hot luxurious water. Also be able to run a load of clothes through the washing machine.

I even went out and cleaned the solar panels of bird droppings and pollen so as to squeeze out as much solar ergs as possible.

 

[Crowz]

We went from 1200 sqft to 4000 sqft and energy changes followed to say the least.

The smaller house has a power bill in the $80 to $120 a month normally and the sticker shock on the new one dropped in at $400 to $600 depending on time of year and family visiting.

I'm happy to say were in the $130 to $180 range now on the new place but it was a slow go getting there and still want it lower. I've had people get lost in the new house. You can go 3 different ways to get to the same destination in it. I spend 90% of my time in a 9x8 room that's my computer room with occasional trips to the kitchen and such so I've tried to keep from heating and cooling the unused areas for now.

The hot water heater stuff is something I'm looking into right now because the 80 gallon electric hot water heater runs more than I care for. The problem isn't the size of the hot water heater as much as how long it has to run to get to some of the outlets (sinks, showers, etc). The distance it travels means tons of heat loss thru the pipes not to mention the amount of water going thru the hot water heater. You have to run the hot water way to long to get it to come out where your wanting it.

 

[Hedges]

Your problem may not be length of pipes, rather those 2 GPM water saving faucets.
If restrictor is in the aerator, may be able to fix that.

I don't think circulator is the solution. That would take care of the delay, but would use your pipes as radiators all day long.
I don't think heat loss from pipes during brief use is necessarily as bit a deal. Loss to air will be relatively slow. But thermal mass of of metal pipe is probably significant.

Point of use heater at some location, maybe. Or small 4 gallon tank heater in-line somewhere.

Have you determined actual watt-hour and cost of the water heater?
With my gas at $8, I estimate electric might be $80, so that could be a significant fraction of your current bill.

 

[Crowz]

Your problem may not be length of pipes, rather those 2 GPM water saving faucets.
If restrictor is in the aerator, may be able to fix that.

I don't think circulator is the solution. That would take care of the delay, but would use your pipes as radiators all day long.
I don't think heat loss from pipes during brief use is necessarily as bit a deal. Loss to air will be relatively slow. But thermal mass of of metal pipe is probably significant.

Point of use heater at some location, maybe. Or small 4 gallon tank heater in-line somewhere.

Have you determined actual watt-hour and cost of the water heater?
With my gas at $8, I estimate electric might be $80, so that could be a significant fraction of your current bill.

I doubt I have water saving anything fixture wise. My plumbing is from the mayflower more than likely (very old house).

I'm leaning towards on demand hot water in select locations. The house was used by a daycare one point and I have 14 sinks scatter thru the house and 3 bathrooms. I'm removing the sinks slowly but people like to make use of hand washing at various locations at times so they still get used.

 

[Hedges]

Is gas available? That might cut water heating cost 10x. Unless you have surplus PV.
Solar thermal batch preheat?

 

[Crowz]

Ive got natural gas and that was going to be the holy grail of savings till the price of natural gas went thru the roof. I paid more in gas this past winter than the electric bill by about double.

So that's made me a bit leery of getting to reliant on gas now. I want it for my generator for sure but I want to ween off of it on other stuff as much as possible. It's not economical generator wise but its like having an infinite gas tank size and in a power outage all I care about it will be it running not how much it cost to run it

 

[Hedges]

What does the math say about gas water heater cost vs. electric?
It seemed to me electric only had a chance to be cheaper with HPWH and DIY $0.03/kWh electricity.
I would think plumbing gas + electric so you could enable either would be best. Assuming they tolerate high temperature input, just plumbed in series, and last one only has to deal with losses through insulation, if first one is enabled.

Generator? CHP!

 

[50ShadesOfDirt]

What was the OP again? Oh, yeah ... storage of excess power ... got lost in the drift.

If propane bottles are a convenient & portable form factor for propane, I can't think of anything better for excess power than (portable) LiFePO4 battery-banks ... emphasis on taking the short-term excess power and storing it long-term, like propane. Everything else seems to be convenience factor (as in, water heater already there).

Load a portable battery-bank up, use it for all kinds of power projects: hand-truck SoGen, recharge of tool batteries, wheel it over to landscape lighting, etc.

CapEx isn't cheap, and some inefficiences in pushing that power around, but it is easy, and you started with free/excess power to begin with ... only your imagination limits the rest of it (in what you'll do with it).

Only thing left is to name it ... PoBank, LiBox? And, pick a color ...

 

[Mart Hale]

Designing an off grid solar solution always seems to end up being a feast or famine situation. You either have more potential than you can use or you fall short of having enough due to battery capacity, Season, weather or unexpected loading. There is no question that the AIO's have helped with this by being able to utilize the grid (or a generator) to make up for shortfalls but since excess can not be sent to the grid for later use, or a compensation payment amount, PV production has to sit idle. Those people that are grid tie never encounter this since they upload to the grid whatever their panels produce in excess of house loads.

You see many folks trying to find a use for extra PV capacity by either manual load addition or automatic dump loads. Other folks add more battery storage so that they can go longer between PV production intervals. Most of the solutions bring their own problems. One being if you get dependent on the "dump" load you added than the times of lower PV production puts you further in the hole. In the case of added battery storage you can reach the limit of not having enough PV to charge back up your battery in a reasonable time frame if it gets drawn down too much. More PV than puts you back into a possible under utilized potential.

My latest setup allows me to manually transfer a hot water heater on if I see my batteries charged by midday. Or I can switch a window AC to run.

Curious of how other off gridders handle the feast and famine times.

After going thru a few famines I figured out that if I use the feast better I will have more for the famine.

On a bright sunny day, I will put on large loads in the morning 7 AM - 10 AM so the battery is down to 30 % for that feast day, this allows me to run the dishwasher, or other heavy loads before the feast kicks in.


Instead of running a clothes dryer, I use fans to dry my clothes.... I have found an efficient fan and use far less energy to dry them.


I try to plan my loads such that the last two hours of the day the battery is in resting mode, so that it is fully topped off at the end of the day.


I use this forecast site, as it shows me cloud cover for the next days time. If there are clouds coming, I scale back and budget the power. Doing this, I have had rarely to power up a generator, as I live in budget.

Summerfield, FL 10-Day Weather Forecast | Weather Underground

Summerfield Weather Forecasts. Weather Underground provides local & long-range weather forecasts, weatherreports, maps & tropical weather conditions for the Summerfield area.

www.wunderground.com

You can see the % of clouds on each day, EXTREMELY useful for planning.

 

[Mattb4]

Off grid solar folks do pay attention to weather forecasts. In my case if I see several days that look to be bad weather I will switch off my second AIO and just run from the one AIO. I flip the breakers so that the array it is connected to connects instead to a SCC that draws very little of operating current. This drops off 50w of idle load while still utilizing both solar arrays.

 

[Hedges]

I plan to do similar for loads with my Sunny Island battery inverters. With 4x connected, up to 3 can sleep at 4W when not needed for load (when off-grid), so only master and any others active consume 25W. Catch is, split-phase gets lost. So I need to connect an auto-transformer (will do that by relay only when off grid.)

 

[EastTexCowboy]

I doubt I have water saving anything fixture wise. My plumbing is from the mayflower more than likely (very old house).

I'm leaning towards on demand hot water in select locations. The house was used by a daycare one point and I have 14 sinks scatter thru the house and 3 bathrooms. I'm removing the sinks slowly but people like to make use of hand washing at various locations at times so they still get used.

I have a similar problem. most things on this house they went first class. Plumbing not so much. There are 2 NG on demand water heaters on the exterior walls either end of the house. That's great. But then they ran 2 miles of water lines to reach the use points. It takes almost 2 minutes for the kitchen faucet to get hot. Not a water saver either. I replaced that already. It's frustrating. And they ran it in uninsulated CPVC which I am no fan of. Fortunately the house itself is 6 inches of blown on insulation so I don't have a problem with frozen pipes, but otherwise it sucks. I may swap for the recirculating kind but not all the pipe is accessible with it being two story. Well, not easily accessible.

It's crazy. Ten ft ceilings, 8 ft custom doors with glass transom lights, oversized high end windows, and a lot of other expensive upgrades, but crappy plumbing.

 

[Hedges]

How about one of these under your kitchen sink?
(would like it to start from cold, throttle down power when hot water finally arrives 2 minutes later)

EcoSmart POU 4T Point-of-Use Temperature Controlled Tankless Electric Water Heater 3.5 kW 120 V POU 4T - The Home Depot

Have plenty of hot water with this POU 4T electric tankless water heater. For convenience, you can install it right at the point-of-use. Energy-saving self-modulating technology adapts energy based on

www.homedepot.com

I don't believe in "on demand" for the house. I prefer tank-type.

 

[Mattb4]

Although the afternoon was not perfect sunny skies, like the morning portended for the day, I still managed to get in a couple of hours heating my water for my shower. It was great though now my cats are afraid of me since I don't smell quite right.

 

[EastTexCowboy]

How about one of these under your kitchen sink?
(would like it to start from cold, throttle down power when hot water finally arrives 2 minutes later)

EcoSmart POU 4T Point-of-Use Temperature Controlled Tankless Electric Water Heater 3.5 kW 120 V POU 4T - The Home Depot

Have plenty of hot water with this POU 4T electric tankless water heater. For convenience, you can install it right at the point-of-use. Energy-saving self-modulating technology adapts energy based on

www.homedepot.com

I don't believe in "on demand" for the house. I prefer tank-type.

That's a good option but it would be a challenge to get a 30 amp circuit to where I need it due to the 2 story thing. I'm pretty sure the DW and disposal are 20a. Still worth investigating though. Thanks.