DIY Home Solar Power System

Dook · February 2019

DIY Solar Power For Home

I live in the California foothills on 10.45 acres. I have a 500' buried power line to my home but every ten years or so we get 6-8 inches of snow and it brings down a lot of oak trees that take out the power lines. It takes them a week to get the power back on. PG+E also shuts off power for as much as 3 days sometimes in the summer if we get a 10 mph wind because they are afraid that trees will down power lines and cause fires, so, I'm going solar.

Down at the bottom of my property I currently have two Sharp 170 watt panels on top of my wellhouse that power my Grundfos AC/DC well pump so that's not a home power need.

My home is 2,590 sq ft and my power use is 3.5 kwh a day in the summer (power bill is about $19 a month in summer) and 5.2 kwh in the winter (power bill is $34 a month). I don't have a wood stove so in winter I run the home heater, which is propane, and I use an electric space heater to heat one room. I'm going to install a wood stove so that should keep my power use at about 3.5 kwh a day year round. The front of my home faces due east but there are three gables on the front so that provides three sides that I can place south facing solar panels.

Can I get traingular solar panels? If not, I measured the gables and they will fit one 385 watt Hanwha solar panel and three 100 watt solar panels. That would be 685 watts an hour, or about 8,000 watts on every sunny day, more than twice what I need. Summers are pure sun every day but in winter the solar will not be able to power the home every day, sometimes we get stormy weather for two weeks straight, so, I would like the system to work with the already installed PG+E power.

How many batteries should I go with? What kind? Can they be installed in a metal cabinet in my laundry room with a small vent to the outside? One battery holds about 1,000 watts? Will the Hanwha solar panel wires connect to panels of other manufacturers? Does it matter if the panels have different voltages, 12 volts or 24 volts vs 39 volts?

Do the solar panel wires go to the charge controller, then the charge controller is wired to the batteries, and the battery power cord goes to the inverter, and then the inverter connects to the fuse panel? The PG+E power comes into the fuse panel from the bottom, how does the inverter connect to the fuse box, from the top?

The panels should be spaced off the rooftop by about one or two inches, correct? Can I just use a couple of 2" x 4" wood beams laid flat and screwed into the rooftop and then mount the panels to the two 2" x 4"? That's what I did with the two Sharp panels on top of my wellhouse. Summer days are typically 90 to 100 degrees F. The roof gets a lot of direct summer sun.

If I screw the 2" x 4" into the roof, through the asphalt shingles, and then mount the panels to the 2" x 4" how do you keep water from leaking down the screw hole and into the home, silicone sealant?

I don't really want to spend $5,000 on a top of the line inverter so I was thinking about using a cheaper 300 or 400 watt inverter that I could turn on and leave on all summer. I would have to switch over to PG+E power a lot in winter though but if PG+E power went out for a prolonged period I would have a day or two of battery power. Will the cheaper inverter power be clean enough for the television? What kind of charge controller do you recommend?

I don't have an air conditioner, so there are no really big amperage drawing start up devices. I have a 45" LED TV, a cable box, a big GE refrigerator, a microwave, a desktop computer and speakers, LED lights in the home, washing machine, dryer is propane heat, propane water heater, propane home heater, and my cooking stove is propane.

I'm planning on installing this all myself except I might get an electrician to check everything and wire the inverter to the fuse box. The system I need won't really be that large and I don't want to send excess power to PG+E. They only pay a fraction of what it's worth. Sorry for all the novice questions but thanks ahead of time for any advice.

petertearai · February 2019

Wow lots of good questions .. You say you plan to wire it all yourself . Unless your an electrician or have an electrical background i would hire a competant person to start with. You asked about mounting solar panels , if you can , consider mounting panels on stand alone frame a lot easyer and no water leaking issues .

mike95490 · February 2019

Look at the "gravity feed pellet stove" - that saves a bunch of power for the glow coil, feed auger and blower fan. But pellets are not cheap.

Dook · February 2019

petertearai said:

Wow lots of good questions .. You say you plan to wire it all yourself . Unless your an electrician or have an electrical background i would hire a competant person to start with. You asked about mounting solar panels , if you can , consider mounting panels on stand alone frame a lot easyer and no water leaking issues .

I'm not an electrician but I will likely get one to wire the system and tie into the fuse panel. What keeps the stand alone frame from moving in wind gusts?

Dook · February 2019

mike95490 said:

Look at the "gravity feed pellet stove" - that saves a bunch of power for the glow coil, feed auger and blower fan. But pellets are not cheap.

Pellet stoves don't work without power. I just went four days without power so my home heater and space heater wouldn't work. The house temperature ranged from 36 to 41 degrees. I have more wood (seasoned oak) than I could ever burn so it's time for me to get a wood stove and some solar panels.

mike95490 · February 2019

New gravity feed pellet stove. takes the same 40# $7 bag of pellets No electricity 40,000 BTU
https://www.tractorsupply.com/tsc/product/us-stove-gravity-feed-non-electric-wiseway-pellet-stove-2-000-sq-ft
"The Wiseway from US Stove eliminates the need for electricity by utilizing a natural gravity feed system that eliminates all mechanical parts meaning less maintenance and break downs. This patented revolutionary design is the only EPA certified and UL Listed non-electric pellet stove on the market today. "

petertearai · February 2019

My frame is made from treated wood . With posts dug well into soil . You can add concrete to the posts/ piles to anchor even more . I think you may find some photos of ground mounted set ups on this site .

petertearai · February 2019

Wow that pellet stove is surely an amaising contraption .kind of ugly but kind of nice ...... all in one go !

Dook · February 2019

mike95490 said:

New gravity feed pellet stove. takes the same 40# $7 bag of pellets No electricity 40,000 BTU
https://www.tractorsupply.com/tsc/product/us-stove-gravity-feed-non-electric-wiseway-pellet-stove-2-000-sq-ft
"The Wiseway from US Stove eliminates the need for electricity by utilizing a natural gravity feed system that eliminates all mechanical parts meaning less maintenance and break downs. This patented revolutionary design is the only EPA certified and UL Listed non-electric pellet stove on the market today. "

Hmm, gravity fed so no electricity... That's an interesting piece of equipment.

I have so much seasoned oak, stacks of it, 10 feet high. I think right now the regular wood stove is best for me.

Dook · February 2019

petertearai said:

My frame is made from treated wood . With posts dug well into soil . You can add concrete to the posts/ piles to anchor even more . I think you may find some photos of ground mounted set ups on this site .

I thought it was some kind of solar panel frame that just sits on top of the roof and doesn't connect through the roof.

Dook · February 2019

What I think I may end up doing to mount the solar panels to the roof without having to put screws through the asphalt shingles is this, lay two 2" x 4" flat, mount the solar panels to them, then, where the 2" x 4" are even with the front of the house I will install a galvanized plate that screws into the front of the 2" x 4" and the front side of the 2" x 6" on the house.

It might look a bit redneck but if I paint the galvanized plate to match the color of the 2" x 6" it won't be as noticeable.

BB. · February 2019

Solar panels can be just big sails if there is a good wind... There are some "ballasted" frame mounts (frame on roof or ground with sand bags)--But I would highly suggest that you buy/build/engineer a strong set of framework.

The panels may weigh 3 lb per sqft... But they are typically snow/wind load rated at 50 lbs per sqft. Your array might be around 35 sqft:

35 sqft * 50 lbs per sqft = 1,750 lbs of wind & snow loading

You don't want your panels taking off in a storm and possibly damaging other property.

-Bill

petertearai · February 2019

Best to have a gap behind panels to help keep cool. Hot panels have reduced output.

Dook · February 2019

BB. said:

Solar panels can be just big sails if there is a good wind... There are some "ballasted" frame mounts (frame on roof or ground with sand bags)--But I would highly suggest that you buy/build/engineer a strong set of framework.

The panels may weigh 3 lb per sqft... But they are typically snow/wind load rated at 50 lbs per sqft. Your array might be around 35 sqft:
35 sqft * 50 lbs per sqft = 1,750 lbs of wind & snow loading
You don't want your panels taking off in a storm and possibly damaging other property.

-Bill

Before my house was finished I lived in a trailer at the bottom of my property and had two large Sharp 170 watt panels laying on top of it for power. One time the wind caused one of the panels to come off the trailer. Now those panels are on top of my well house, which has an angled roof towards the south, and I just have screws close to the panels as friction to hold them down and they've never moved.

Dook · February 2019

petertearai said:

Best to have a gap behind panels to help keep cool. Hot panels have reduced output.

Yeah, I learned that. My two panels down on my well house were just laying on top of the corrugated metal roof and I checked them out one day and one of the panels was delaminating on the bottom. They were getting too hot in summer so I put two 2"x 4" flat on top of the well house underneath them to give the back side some air. I'm going to do the same thing when I put the solar panels on top of my roof. I'll have two 2" x 4" laying flat underneath them.

Dook · February 2019

I'm the only one living in my home and I use 3,500 watts a day. I've looked at the typical power use for the devices I have but something must be wrong with the listed power use because I'm not using anywhere near what they are supposed to be drawing. Is the following correct: 42" LED television: 300 watts 14 hours a day Desktop computer: 50 watts 14 hours a day Computer 27" monitor: 30 watts 12 hours a day Computer speakers: 15 watts 14 hours a day New large refrigerator on always 80 watts kicks on for maybe 20 minutes each day Microwave: 1,500 watts 5 minutes a day All lights are LED 300 watts 30 minutes a day TV Cable box 15 watts 24 hours a day Washing machine, twice a month ? Phone, camera, electric shaver recharge negligible

WaterWheel · February 2019

They make racks designed to securely mount to your shingle roof with no leaks.    But first verify that your shingles are in good condition. It would be a shame to need to replace the roof 4 years after you mounted the panels.

Start with the batteries. It looks like you already know what your needs are (5.2 kwh/day) so first we need to size the battery bank. 2 days of no sun reserve while keeping the batteries above 50% SOC (state of charge) so about 21,000 watt/hrs of storage.    If you go with a 48v battery bank and have one string of eight 6v L-16 sized batteries which may be a good choice. The fewer battery strings the better and the 48v allows you to use a smaller charge controller. Batteries require regular maintance if you want them to last.

To properly charge that 420 amp/hr 48v battery bank at roughly a C/10 rate you need enough panels to provide about 42 amps at 58v (charging voltage). After taking in panel and charge controller inefficiencies into account you need about 3000 watts worth of solar panels.    A 50 amp or larger charge controller will work fine.
Ground mounting the panels will help you keep the snow off or some people mount some of their panels vertically on a wall so the snow falls off.

It looks like all of your loads are 120v so you may be able to get away with an inverter like this one.    https://www.solar-electric.com/magnum-energy-ms4048-20b-sine-wave-inverter-charger.html
To help that washing machine run smoothly you're probably going to need at least a 2500 watt inverter with the ability to surge over 4000 watts.
Don't buy a cheap AIMS type inverter that uses tons of power while just in idol.

Yes, since you'll be using some of your daily power while the sun shines you can probably get away with a slightly smaller system or use a cheap inverter but if you want a quality system you need quality parts that are sized for the job.

Dook · February 2019

WaterWheel said:

They make racks designed to securely mount to your shingle roof with no leaks.    But first verify that your shingles are in good condition. It would be a shame to need to replace the roof 4 years after you mounted the panels.

Start with the batteries. It looks like you already know what your needs are (5.2 kwh/day) so first we need to size the battery bank. 2 days of no sun reserve while keeping the batteries above 50% SOC (state of charge) so about 21,000 watt/hrs of storage.    If you go with a 48v battery bank and have one string of eight 6v L-16 sized batteries which may be a good choice. The fewer battery strings the better and the 48v allows you to use a smaller charge controller. Batteries require regular maintance if you want them to last.

To properly charge that 420 amp/hr 48v battery bank at roughly a C/10 rate you need enough panels to provide about 42 amps at 58v (charging voltage). After taking in panel and charge controller inefficiencies into account you need about 3000 watts worth of solar panels.    A 50 amp or larger charge controller will work fine.
Ground mounting the panels will help you keep the snow off or some people mount some of their panels vertically on a wall so the snow falls off.

It looks like all of your loads are 120v so you may be able to get away with an inverter like this one.    https://www.solar-electric.com/magnum-energy-ms4048-20b-sine-wave-inverter-charger.html
To help that washing machine run smoothly you're probably going to need at least a 2500 watt inverter with the ability to surge over 4000 watts.
Don't buy a cheap AIMS type inverter that uses tons of power while just in idol.

Yes, since you'll be using some of your daily power while the sun shines you can probably get away with a slightly smaller system or use a cheap inverter but if you want a quality system you need quality parts that are sized for the job.

Thanks for the reply and the information. I don't need 5.2 kwh a day. I know you don't believe me but I use 3.5 kwh a day for most of the year. The 5.2 kwh was only during winter months and that was because I ran the home propane heating unit fan and a space heater. I'm getting a wood stove so I won't be using the home heater or space heater very much, if ever. So my use will be 3.5 kwh year round. One 385 watt and three 100 watt panels will provide double my need. The three gables I have on the front of the home provide perfect south facing directions for solar panels. Snow will cover them but since they will be near the front of the home I can clear them with a broom the same way I clean the TV dish and internet dish of snow. I'm figured I would need about six to eight batteries. I don't know about the inverter yet, still doing research.

mike95490 · February 2019

> New large refrigerator on always 80 watts kicks on for maybe 20 minutes each day

I find that very hard to believe, that a large fridge can stay cold by running only 20 min daily.

Dook · February 2019

mike95490 said: > New large refrigerator on always 80 watts kicks on for maybe 20 minutes each day

I find that very hard to believe, that a large fridge can stay cold by running only 20 min daily.
I don't know how often it kicks on but I leave the television on for 14 hours a day (I'm retired) and I'm on the computer for 12 hours a day and somehow I'm only using 3.5 kwh. So, however you want to figure each device, they all have to fit into 3,500 watts a day. My neighbors use much more power than I do but mostly that is because their well pumps have to kick on every time they use water. My water pressure comes from a large water tank that is about 50 feet above the house on a hill.

petertearai · February 2019

Maybe get a little kwh meter and check each device for 48 hours .. then add them up . The fridge freezer in my house uses around .7 tk .8 kwh per day .

Dook · February 2019

petertearai said:

Maybe get a little kwh meter and check each device for 48 hours .. then add them up . The fridge freezer in my house uses around .7 tk .8 kwh per day .

I don't have to check every device because my monthly electric bill shows my daily kwh average and monthly kw use. We're just going around and around and around, going over the same information that I've already posted in the original post. You guys should call this DIY solar power forum the "Carousel."

I'll find another forum.

WaterWheel · February 2019

Dook said:

One 385 watt and three 100 watt panels will provide double my need.
I'm figured I would need about six to eight batteries. I don't know about the inverter yet, still doing research.

Be careful when mixing panels.    The current and operating voltage needs to be very similar between the panels or you're not going to get good output with that 385 watt panel you've got.

Many people make the mistake of getting their panels before considering the rest of the system.    I like to first consider the load, 3.5 kwh/day in your case, then figure what size battery bank will support that load for 2+ days without dipping the batteries below 50% SOC (state of charge).    Then you can figure how many panels you'll need to properly charge the batteries.

Last comes the AC side of the system like the inverter and breaker box.    Buy nothing until you've figured the entire system out. A long lasting and efficient solar system needs to be balanced, particularly between the loads and the battery bank and between the battery bank and the panel sizing.

mike95490 · February 2019

I'll do it.

> 5.2 kwh in the winter (power bill is $34 a month).

So you need battery storage of at least 3x that amount. 16Kwh of storage. What can provide that?
My seat of the pants spreadsheet says 4, large Marine batteries would be comfortable @ 48V. If you could
save a bit of power and get to the 3.5kwh summer usage (10.5kwh storage), you could get away with 2 batteries and a 24V system

For each 100A of capacity, you need 10A of charging, so 90ah batteries in series need 9A of charge at the appropriate voltage
for a 48V system. you would need enough panels to harvest about 500w for 3 hours a day. Assume about 600 - 700w of well aimed panels to acomplish this, more panels if they are not well aimed. Look at the 200-350W panel sizes, cheaper price/watt than 100w panels.

Image: https://us.v-cdn.net/6024911/uploads/editor/ff/4e50jy7f282h.jpg

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petertearai · February 2019

Sorry to hear your not happy with the discussions .
This forum has a good number of people with experience to chat to . My reason for suggesting an other check was to see if you house meter had gone on a slow down and your getting an incorrect reading .old mechanical meters can do that ,although unlikely .. you did mention that you found your consumption quite a bit different from your neighbours . I would have thought it couldn't be explained by the water pump.
.

MrM1 · February 2019

Dook said:
I'll find another forum.

Try solar panel talk ... They'll tell you what u want to hear.

Or if u copied the system in my sig at 3.5 kwh per day it would just about get u there for $7k. Have no idea Ur budget. To do it over I would have gone 48v inverter, 4 more batteries for 1 sting at 48v an 3 more panels. It would have cost about $1k more

littleharbor2 · February 2019

MrM1 said:

Dook said:
I'll find another forum.

Try solar panel talk ... They'll tell you what u want to hear.

That's some funny stuff there.
Maybe you'll have the pleasure of having SunKing will answer your questions.

wellbuilt · February 2019

Sun king is a funny guy , that will be some good reading

Ampster · February 2019

littleharbor2 said:
That's some funny stuff there.
Maybe you'll have the pleasure of having SunKing will answer your questions.

Pleasure? LOL. 50% of what Sunking says is useful. The rest is vitriol and peppered with insults. I am also on that forum with the same handle and haven't seen a post from him in 30 days.

I did get banned from that forum for 10 days for suggesting that one could install a solar and battery system and one would not have to get permission from the POCO. Of course you would need a building permit and that would imply that you would need UL approved equipment and be able to configure your equipment for non export. I have researched this and not found any rules or ordinances that prevents anyone from generating their own power. There are plenty of rules that say if you are served by the grid you cannot go off grid, but that is not what I am talking about here.

BB. · February 2019

Ok guys... Let the thread go....

-Bill

Ampster · February 2019

Sorry for the digression.

DIY Home Solar Power System

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