Rudimentary questions.... i'm new.... please be gentle....

Fulthrotl

Fulthrotl

~Autocorrect is My Worst Enema.~
Location
HB, CA (19 Hrs. 22 Min. from Winged Horses)
Occupation
E
i'm contemplating, finally, panels on my house. so, i have questions....
i'm painfully new to all of this, and rather than wade thru the internet,
i figured i would just come and ask here.

in a perfect world, something modular like an ecoflow whole house
battery system would provide whole house supply, and the POCO
would simply top off the batteries in the event of sunlight shortfall.

roof was done 18 months ago, and so it's fresh. glace fire and ice
was used under comp shingles, on fresh OSB underlayment, so i
should be able to do racking with minimal grief.

the back side of the house is where PV's will sit, and it's pretty
hippy and convoluted, so total square footage is about 1K, so
efficient panels to maximize yield would kinda be a thing.

there will be a panel upgrade, and i can refeed home runs as
necessary to a sub panel driven by the inverter, so the only load
on the service is feeding the battery/inverter.

so, i guess i'm looking for what you guys like in hardware.....
panels, racking, components that go in the direction i'm headed.
once i know where i'm headed with hardware, i can see if this is
feasable.

house is about 1,700 sq. ft. located in so. calif.

thanks for any insight. figured this is the best place i could go for
info.
 
Fulthrotl said:
ecoflow whole house battery system would provide whole house supply,
Click to expand...
A quiet inverter generator on standby will outlast lithium battery cycling, with superior capacity.

Modern EVSE are being designed with 2-way power transfer for whole house batteries.

No reason to pay rent twice for the same lithium junk. NEC also makes the exception for GFCI, with 2-way power transfer.
 
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@Fulthrotl
Clarify your goals for us.
Is bill savings or backup power more important (or both)?

If you want automatic transfer for whole home (or a significant portion of a home) then it's critical to understand which piece of equipment is your MID (micro-grid interconnect device). System design is largely built around that but it's quite variable how different manufacturers implement it.

Rapid shutdown compliance pretty much requires micro-inverters or optimizers. Batteries without UL9540A certification may make approval a PITA.

Module cell efficiency is generally less important than price per watt, but top tier residential modules these days are all pretty efficient.

I don't agree with ramsy's advice and his comments about bidirectional EVSE are, unfortunately, not really true yet. EV manufacturers mostly haven't given the go ahead. The only one really out there is Ford, which isn't compatible with anything else and may be of limited availability.
 
ramsy said:
Enphase appears mature,
Click to expand...

Yes I'm confident Enphase will be the first major manufacturer to market with a fully integrated V2H+solar+home battery solution ... as soon as they can secure cooperation with an EV manufacturer.

and there are several others
Click to expand...
Australia? Anything on that page available in the US?

expecting bidirectional model EV’s.
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Key word 'expecting'. No actual products mentioned on that page.

I think it will be here within the next five years, but that's what I thought 5 years ago. There's definitely been progress. It's clear at this point the holdup is not technological.
 
jaggedben said:
Clarify your goals for us.
Is bill savings or backup power more important (or both)?
Click to expand...
yes. ;-) the driving desire is to be self sufficient.

and while tariffs may skewer stuff, and last year may have been a better time to buy in,
hindsight has never been that useful. it is what it is.

so i'll need to do a load calc and see what i draw, and balance the system to that, but
i'd like a system that'll charge off peak to say 70%, so it'll only charge when the system
has really been pulled down, and if i've designed it correctly, i'll seldom need power.

while i can start with referencing my electric bills for load, i have a fluke meter that will
clamp on nicely, and show me what is going on.

i'm not running AC at this time, but will be adding it this year i want a new forced air unit,
so now is the time..

my utility bill without AC is running about $300 a month, so any savings can offset the
cost of the system, which i suspect will be substantial. i don't want to sharecrop my
roof to the POCO, and generate for them. weather events like hailstones aren't an issue
here,

usage without AC is running about 700 kwh a month, and it looks like the hightest month
was 775.

so in true grumpy old man mode, i'd like to run standalone.

here's what the .gov calculator says i can pull off my roof. it'll be a lot less than that.
i'll have to cad the roof to see how many panels i can get on there.

1746726611308.png
 
Fulthrotl said:
here's what the .gov calculator says i can pull off my roof. it'll be a lot less than that.
i'll have to cad the roof to see how many panels i can get on there.
Click to expand...

The PVWatts estimate looks quite high. Do you mind sharing your inputs?
Fulthrotl said:
the back side of the house is where PV's will sit, and it's pretty
hippy and convoluted, so total square footage is about 1K, so
efficient panels to maximize yield would kinda be a thing.
Click to expand...

If you pack 1000 square feet of roof perfectly with perfect solar panels I think you will get less than 1/2 of your estimate.

With a good solar resource, best bang for your buck is to maximize the PV production, shift consumption to match production, use the power company when necessary, and ignore the batteries. The cost of putting (an essentially free) kWh into a battery and then getting it back out again, when you consider the cost and depreciation of the battery is likely 2-4x the cost of electricity bought from the power company.
 
winnie said:
The PVWatts estimate looks quite high. Do you mind sharing your inputs?


If you pack 1000 square feet of roof perfectly with perfect solar panels I think you will get less than 1/2 of your estimate.

With a good solar resource, best bang for your buck is to maximize the PV production, shift consumption to match production, use the power company when necessary, and ignore the batteries. The cost of putting (an essentially free) kWh into a battery and then getting it back out again, when you consider the cost and depreciation of the battery is likely 2-4x the cost of electricity bought from the power company.
Click to expand...
the inputs were wildly optimistic, and came from here:

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations
pvwatts.nrel.gov pvwatts.nrel.gov

if i could pull 2kw, i'd be quite happy.
i figure with AC, my load will be 1,600 ish a month,
about double what it is now. i've got window shakers
in three bedrooms now, and that will change to central AC.

the batteries are more from a self sufficient point of view.
i won't live long enough to break this thing even, i suspect.
at this point, i want it 'cause i want it.

i still work from home, as does my wife. i've mentioned a few
times about whole house battery would be a good thing to have,
and last month, the power went off for three hours in the middle
of her database manipulation, and there is nothing like a slap in
the face to get one's attention, is there?

the largest running load i have is the pool pump, and right now,
the app says it's pulling 465 watts, doing 50 GPM for six hours,
during the daytime, which is my lowest cost period here. you can
run it slower and shorter in the winter, but chemicals and power
all increase when the temp goes up.
 
Yeah that PV watts estimate must be for an approximately 30kW system, which is actually the limit in California for a standard residential interconnection. For 700kWh/month you probably only need a 5-6kW system to cover annual consumption Okay more to cover the AC.

We use a software service to analyze usage and production and calculate bill savings with battery cycling and maximize payback time. If you are adept with spreadsheets and have lots of time you can probably download your utility data from your online utility, as well as hourly data from PVWatts, and figure out how to do something similar, if you really want to understand how it might work. Otherwise it's very much a guessing game, but a reasonable design process might be as follows:

Design the solar system to produce as much energy as you use in a year (probably actually that's somewhat overkill for bill savings). Analyze how much battery you need to store your average daily overnight usage, then add more battery capacity (double it?) for as much as you want to have a 'backup reserve' for outages. You can oversize the solar system to try to be more self- sufficient in winter months but at a certain point it will be a big net loss (bill savings will never cover additonal cost). Also the utility likely has limits on the size of your solar compared to your usage, so don't go too big without getting utility approval before you install.

Don't try to be completely off grid, if money is a controlled substance. 😉 If you avoid 70% of annual utility imports you've done well.

A company like Enphase comes with everything software ready to maximize self-consumption and bill savings. Other offerings might be cheaper and you may like certain aspects of the installation more, but may require you to be your own software and support guru to a much greater extent.

It's hard to give comprehensive advice over a forum like this. But hopefully that helps.
 
while there isn't an EV in the house now, it's probably gonna be
a thing, so i'll need to put in a branch circuit to the garage to run
that.

then there is where to charge it from? perfect world would be
a slow charger off the battery pack, with a fast charger off the
main house panel, during the daytime.

our off peak is during the day, at .23 per kwh. it spikes to .65 kwh
at night, when everyone is charging their car to go to work in
the morning.
 
wwhitney said:
Right, but what values did you put into the calculator?

If I input Huntington Beach, CA, and stick with all the defaults (of which the most salient are 4 kW DC, 20 degree tilt, 180 degree azimuth), it spits out 6,593 kWh/year.

Cheers, Wayne
Click to expand...
agreed. i drew in the back half of my house, and it calced it like it was perfect, which it is far from that.
 
Fulthrotl said:
while there isn't an EV in the house now, it's probably gonna be
a thing, so i'll need to put in a branch circuit to the garage to run
that.

then there is where to charge it from? perfect world would be
a slow charger off the battery pack, with a fast charger off the
main house panel, during the daytime.

our off peak is during the day, at .23 per kwh. it spikes to .65 kwh
at night, when everyone is charging their car to go to work in
the morning.
Click to expand...
You don't really want to dump your home battery into the car if you're running off grid. Most likely your car will have enough charge to leave town in an emergency, and you'll want to use the home battery for the home.
Put the fast charger on a non-backed up circuit, and don't plug the car into a backed up slow charging circuit unless you really intend to when already off-grid.

Depending on the design details you can usually have the battery monitor your whole house usage to supply energy to non-backed up loads during normal on-grid operation.
 
jaggedben said:
Yeah that PV watts estimate must be for an approximately 30kW system, which is actually the limit in California for a standard residential interconnection. For 700kWh/month you probably only need a 5-6kW system to cover annual consumption Okay more to cover the AC.

We use a software service to analyze usage and production and calculate bill savings with battery cycling and maximize payback time. If you are adept with spreadsheets and have lots of time you can probably download your utility data from your online utility, as well as hourly data from PVWatts, and figure out how to do something similar, if you really want to understand how it might work. Otherwise it's very much a guessing game, but a reasonable design process might be as follows:

Design the solar system to produce as much energy as you use in a year (probably actually that's somewhat overkill for bill savings). Analyze how much battery you need to store your average daily overnight usage, then add more battery capacity (double it?) for as much as you want to have a 'backup reserve' for outages. You can oversize the solar system to try to be more self- sufficient in winter months but at a certain point it will be a big net loss (bill savings will never cover additonal cost). Also the utility likely has limits on the size of your solar compared to your usage, so don't go too big without getting utility approval before you install.

Don't try to be completely off grid, if money is a controlled substance. 😉 If you avoid 70% of annual utility imports you've done well.

A company like Enphase comes with everything software ready to maximize self-consumption and bill savings. Other offerings might be cheaper and you may like certain aspects of the installation more, but may require you to be your own software and support guru to a much greater extent.

It's hard to give comprehensive advice over a forum like this. But hopefully that helps.
Click to expand...
thanks. and, yeah, there is a point of diminishing returns. and yeah, you did help.

and i don't draw a ton of power now. i figured if i could offset 75%, going bigger would be a waste, unless i wanted to run off the grid entirely. and if there were an extended power outage, which is unlikely but possible, the house can run on 3kw easily. i can pull the meter, and feed the entire house off the inverter in the jeep. except for the induction range. the jeep has 3kw, 400AH on board, but not 220. it's just a jeep.

the ecoflow top tier unit still has pre tariff pricing, so they loaded the front end, for a while anyway.
 
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