diy solar

diy solar

How to size based on usage + location?

solarflare

New Member
Joined
Dec 26, 2019
Messages
9
Location
Ohio, USA
While the prices of panels have come down, the worry about battery cost has really kept me from moving ahead... up until I saw the recent video on YouTube with the clear lowering of battery prices.

I have a home that has electricity requirements that are as much as a home mortgage each month. It's insane and I can't seem to lower our power consumption requirements due to location and other limiting factors. Here's the past 12 months of usage:
Image+2019-12-26+at+2.08.01+PM.png


We're located in a small valley in southern Ohio that's in between Columbus, OH and Charleston, WV. Got these values from https://www.wholesalesolar.com/solar-information/sun-hours-us-map:
CITY: Columbus (OH)
HIGH: 5.26
LOW: 2.66
AVERAGE: 4.15
CITY: Charleston (WV)
HIGH: 4.12
LOW: 2.47
AVERAGE: 3.65

Basically we have a lot of roof space facing west-south-west.

I'd like to build the entire system out myself since I have a background in electronics. Last time I sized this up I was looking at over 30k USD, which is way, way, way out of bounds for my budget.

I would really appreciate any thoughts / help on not only sizing up requirements, but also in selecting panels and pulling together a plan that would allow me to build the system up over time so as to basically start of small-to-medium range and then expand it up as funds become available. My ultimate goal is to entirely replace the grid except during really bad weather and even then having a fully charged battery array that would allow us to operate with minimal services for extended periods of time if needed.
 
My house was averaging 960 kWh in Kansas.

I put a 6 kWp solar system and just setup ~36 kWh of batteries for peak shaving. It is expected to produce 720 kWh per month, and has done so for the first 4 months nicely.

Now my grid usage is about 300 kWh.

You are looking at some huge bucks to do 6000 kWh

If you want to do retail with Tesla Powerwall expect $14,000 per wall installed, each is 14 kWh, you would need 12.

You are using about 165 kWh a day.

I am not sure I have ever seen something like this, as residential.

So, how to go about this elephant? (one bite at a time)

Solar panels (are you limited on size by your grid/utility?)
My 6.2 kWp produces basically 26 kWh a day. (scale that to yours, basically 7 x)
So you need 40 to 45 kWp of panels to make 165 kWh a day.

I have about 32 kWh of (used BYD batteries) and I only need it for 6 hours 5 days a week), if you scale that up to your power use, 220 kWh of batteries.

So, first how much power do you want to offset from the grid?
Do you have a time of use fee or demand tariff?

How much kWp does that $30k get you?

kWp - kilowatts potential of solar panels
kWh - amount of kilowatts used or how much energy batteries have.


Here is a DIY setup that I just completed and today I am running it live day #1!!!

I am at $7000 for about 32 kWh using BYD batteries and have 10kW (2xLV5048) of inverter, I can run my entire house on my batteries. (If tesla did it, the price would have been $28,000.)

My solar system was $18000 installed retail (I imagine about half that price if DIY).
 
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I have no real limitations as far as I know with American Electric Power (AEP) in Ohio. I've got a roof that's long and flat - about 20' x 100' on one side that primarily faces the sun (west-southwest).

My goal is to build a metal shed to house all of the batteries and controllers so as to isolate it from the house in case of any "problems". I'd obviously like to make this shed initially as large as it will ever need to get to simply not have to build onto it at a later date. I could use old fashioned car batters as far as I'm concerned if cost would make it worth it.

I'm more interested in cost + reliability and so size is no issue for me.

The video here about the LiFePO4 CALB really got my gears turning. I think it's even better than the RUiXU battery option here (which clearly seems to indicate that standard car batteries are non-starters now).
 
Just forget about using car batteries altogether, whatever "capacity" they have, instantly cut that in half, then whatever cycle life they have, cut that in half also. They are simply not at all suitable for long term continuous use. Car batteries are actually in the long term nearly 4 to 12 times the cost as any lithium-based battery setup.

Right now the goto for DIY is any crashed car EV battery, Nissan Leaf, Chevy Volt, Tesla S/X.

So for starters, the question is, how much energy usage do you use at any given moment. This way you can figure out how much of an "Inverter" you need.

The simplest way to get that answered is to go outside and look at your meter and see what the usage is when most everything is running. I can make mine go maybe 15 kW if I charge my car, run the dryer, microwave, heater and everything else in the house all at the same time. At night when nearly everything is off, I'm using about 600 watts though. (Right at this very moment, my house is using 1050 watts). Start off that way, add a Emporia Vue, or Sense monitor.

It's important that you understand how much energy you use so you can know how much to supply it with.

First Inverters - remember they are scalable, go about 25% larger than what you think your peak usage would normally be.

Next Solar and Batteries - How much "backup" do you want? Remember Solar only works part of the day, the worst thing about solar is that when you produce more than you consume, it gets put on the grid and vanishes into nothing. So a system should really send that excess to the batteries, not the grid. In the long run, you get nothing for giving your energy to the grid. Credit is just that, you receive nothing but a lower bill, you get nothing back.

To do a 165 kWh a day of solar in Ohio, might take about ~90 to 95 kWp, which is M A S S I V E. I'm talking like 300 panels of 300 watt panels.
 
I'm just curious where all of that energy is going. Are you running a factory in the back? Is someone leaching your power to mine Bitcoins? To me this seems extraordinary in a way that it must be wrong... I can't believe this is a regular family home. It seems it's not too hot, nor too cold where you're at if I see that right.
 
I'm just curious where all of that energy is going. Are you running a factory in the back? Is someone leaching your power to mine Bitcoins? To me this seems extraordinary in a way that it must be wrong... I can't believe this is a regular family home. It seems it's not too hot, nor too cold where you're at if I see that right.
Grow lights. ?
 
I do have a TED (The Energy Detective) hooked up and here's what I'm seeing for the past day:
Going back a bit further I saw

Wow!

Yep, my guess was about right. I have no idea how it's possible to have that much power usage, but you are doing it.

Now, let's look at what your objective is.

What is your objective?

You can spend $40K on parts real easy, to save you $200 a month. Does that make sense? I spent on my system the equivalent of 9 years of electricity bills and now my monthly bill is about $16. What is 9 years of electricity bills for you? 9600x9=$86400. I have solar, and I have a battery, but they are not connected. The battery is used during the day from 2:00 to 7:00 to negate the demand tariff. In hindsight, I still think my setup is best for negating the utility price gouging. I manually switch over and have two breif outages for some of my stuff not plugged into UPS's M-F.

With as much usage as you have, I imagine the power company hits you a lot of demand usage on your bill.

We do not have access yet to flow redux batteries. For as much usage as you have, that is the only reasonable option that I can see.
 
I'll be frank here. I've been scratching my head and fighting electricians for years. Every time I talk to someone in a forum (kinda like here) I get laughed out of town and I usually just go away. I'm not saying anyone's outright rude - it's just that I don't know what to do. I've literally had fights with AEP over this situation. We do use a lot of electricity with an office at home (many computers and servers, but even these only average out to around 1kw max it seems when they're all on) and a 3200 sq ft home that's single story. We poured a bunch of money into insulating the attic to very little avail.

The only real odd thing that I'm seeing (and I've argued with others about this locally) is that when my primary furnace heating elements circuit kicks on, it jumps to about 10k watts with another 4-5k watts on the "blower" circuit. This 14-15k watt surge tells me that there's something weird going on, but frankly it's back off after a matter of a minute it appears.

Again, I've had folks locally tell me again and again and again (for about 10 years now) that my energy usage for this size house is "normal" for our area. I have a very, very hard time swallowing that.

But yeah, here I am. AEP is going to bankrupt me. I'd like to figure out another option, but I cannot for my very life figure out what is actually going on.

I'm about to say "eff it" and rent a dozer and excavator and cover my house in plastic sheeting and BURRY most of it! I'm really trying to figure something out out of desperation at this point. I wouldn't mind throwing a few hundred dollars a month towards resolving this issue such that perhaps by this next summer I've got some of this monkey off of my back, but yeah, it's a very very hard nut to crack.

You'll have to forgive me, it's been a rough day. :LOL:
 
I have 960 sq ft house when my heater kicks on, the fan blower hits 1.5 kW for about 3 seconds then drops to about 500 watts while it's blowing. Just like any induction motor, there is the surge when it turns on, but 15 kW in your case makes no sense. Mine is only 3 years old though, but 15 kW is more than 60 Amps, you would flip your circuit breaker every time it turned on. Are you on a gas or electric furnace? I've never seen or used an electric furnace so I have no idea how much juice they suck.

PS - on a side note, I put about 10 inches of blown-in insulation in my attic, then I watched a whole bunch of what to do and what not to do videos. This spring when It's not so cold and before it gets hot, I'm going back up there to SEAL it with foam. Every stupid hole in the rafters from the lights and the electrical wires adds up, and is the cause for about 50% of the heating!
 
Electric furnace x2 (one for main portion of house and one for the addition, BUT the addition is essentially always off since computers keep the large office area warm and space heaters are used elsewhere when needed). The big spikes you see are for the main portion of the house's furnace.

Yeah, we've got about 20 inches of blown in insulation in the attic. It dropped our electric bill by about $50 a month when we added it several years ago.
 
Let me just pop on the minutely view for today as an eyeopener:

Anything come to mind when seeing this insanity?
Here is my "today" grid usage. I'm charging my car right now also.

Go take a photo of your loads panel, let's see what ya have.

Screenshot_20191226-214515.png IMG_20190820_234908020.jpg
 
Electric furnace x2 (one for main portion of house and one for the addition, BUT the addition is essentially always off since computers keep the large office area warm and space heaters are used elsewhere when needed). The big spikes you see are for the main portion of the house's furnace.

Yeah, we've got about 20 inches of blown-in insulation in the attic. It dropped our electric bill by about $50 a month when we added it several years ago.

Well, the low hanging fruit is the furnace fan. That thing kicking on looks like it rusted in place and taking everything in the county to get it to turn again. But it only looks like it is running every 90 minutes or so. It might even be a hard drive bank spinning up. But I can't possibly see how an HD could suck that much juice just turning back on.

Another low hanging fruit is changing bulbs to LED's. I have 23, I turn them all on and it's 150 watts.
 
Well, here are the past 4 hours of minutely readings (fairly sane compared to when spikes are occurring since it's been around 50ºF all day and furnaces have not kicked on):
skitched-20191226-230828.png


Main breaker (old open pic from a few years ago WITHOUT TED; still same but of course I DO have a cover on it and TED makes it a lot messier now):
IMG_6436.jpg


Secondary breaker (same story as Main):
IMG_6439.jpg
 
Solarflare, I'm sorry if I came across as laughing at you, that was not my intention. However I do believe your priority should be to figure out what is causing this extremely high usage and fix that. I think starting with the furnace is a good idea, and then go through all the other stuff that could potentially cause the issue and turn it off, monitoring for changes.
 
Holy. Crap. Thats a lot of power going somewhere. You have a 5kw base load never mind your usage spikes - thats 120kwh a DAY. In comparison I have a gas furnace/hot water here in the pacific northwest and we use 830kwh a MONTH and thats actually kind of high.

The only thing I can think of is that you start turning off breakers one by one and monitor your usage load to isolate where all the power is going.

Maybe you have a electric radiant heat embedded in a concrete slab thats not insulated from the ground underneath or bad hot water elements that are so calcium-ed up they can't get their heat to the water very well so all they do is burn power.

Your best bet might be to changeover to a air or ground source heat pump system instead of a straight resistive heat system. From what I understand you get something like 5 times the amount of power used in a heat pump returned to you in heating or cooling. If you have a straight electric house your utility company probably has rebates and incentives on changing over to a heat pump system.

For that matter you could avoid your main furnace alltogther and install ductless mini splits, one central compressor with 8 distributed heating/cooling heads you can put in various rooms either on the wall or in the ceiling if going through the attic is easier. I installed one with a single head here myself and it's just not that hard, just a PITA. Also, each room gets its own thermostat.

Luckily, solar panels have gotten cheap; 35 cents-ish a watt if you shop around, but you'll need a awful lot of space to mount what you need so you might want to think about a ground mount. Your big expense isnt going to be the panels, it's going to be the inverter, especially if you want a local battery backup. If primarily what you want is to knock down your utility bill your least cost option will be to mount the panels and use the cheap Sunny Boy grid interactive inverters on ebay right now. You'll need about 3 of them. If your utility supports it you can net meter and any extra you produce gets put into the grid like a 'battery' and you get kwh credits that you can then draw back at night time.
 
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I feel I must also chime in here. First Rule of Solar is simple, Conservation is cheaper than Generation or Storage and always will be, no matter what. You mentioned an Electric Furnace, there IS one beast you are hunting for, baseboard heaters if you have any, then the Hot Water Tank (suspect if elements are not good but I it is a major power hog in any case). Central Air Conditioning can also be a huge drain on power, especially older units, heat pumps & mini-splits are much more efficient. Anything that uses resistance is a power sucker.

I had a 3500 Square Foot Cape Cod style house modern built (late 80's) & well insulated. my computer room had 4 quad servers and 4 workstations & 1 heavy Graphics Animation station (severe energy pig). The Power KILLERS in the house , Electric Forced Air furnace, 60 Gallon Hot Water Tank, 1970's 22 cu foot freezer. Those three power pigs accounted for 75% of the energy bill every month and it was ludicrous in winter ! Luckily we had a wood stove in the basement and so 20 cord of wood every year helped manage that. BTW: The cookstove was a Caloric Professional Series propane range so it had no effect on the power usage as such, except for it's hot Glow Bar in the oven when in use. That house is now sold and I moved on....
 
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