Archive for Solar Power

How to make a light duty solar panel junction box

If you have multiple solar panels and you want to connect them together to form an array, it is very helpful to create a solar panel junction box to help keep the wiring organized, and to also help eliminate reductions in voltage or watts coming from the solar panels.  In this write up, I will describe how to make a light duty solar panel junction box.  My definition of a light duty solar panel junction box is a box intended to be used to join low voltage, low amperage, low wattage solar panels together in parallel.  If you have 12 volt solar panels under 5 amps, that use 18-12 guage wiring – then this box will work for you.  If you have higher wattage solar panels that use MC4 connections, I recommend you view my write up for a heavy duty solar panel junction box.

When I created this light duty solar panel junction box, my intention was to create a solar panel array that was composed of 6 15 watt solar panels all wired in parallel.  This way the amperage and voltage would stay the same, but we would be increasing the joined wattage of the panels at the junction box.  I had started with two of the harbor freight 45 watt solar panel kits that use 12 guage wire and do not produce a lot of juice compared to larger panels.  I planned to install these panels on the roof of my garage, run the wiring to the junction box, and then run the junction box to a charge controller that would regulate my battery bank.  I wanted to keep the setup as simple and clean as possible.  The junction box you are creating is basically just an enclosed positive and negative bus bar that joins all of the positive leads of the solar panels to one bar, and all of the negative leads of the solar panels to the other bar.  Again, this is parallel wiring, so the amperage does not increase, the voltage does not increase, but the wattage does increase.

Step 1:

Go to Radio Shack and pick up the following items:

1) Project Box Enclosure

2) Barrier Strip – 8 or 12 position

3) Jumper Strip (if they do not have anymore, get a pronged electrical connector that can be used as a jumper

4) Grommets

5) 12 guage wire with two leads.  If they only have 1 lead, then get two reels – 1 red and 1 black

6) Super Glue

Step 2:

Take out the Barrier Strips and Jumpers and connect the jumpers to the barrier strip:

Step 2 option B if no jumpers are available:

Step 3:

Super Glue the new barrier strip with junctions inside the project box:

Step 4:

Drill a holes in the bottom of your project box large enough for two wire lead in the bottom of the junction box, and drill one giant hole (largest grommet size) in the top of your box for all of the leads from the solar panels, and install your grommets.  Connect one of your wires leads to one strip, and one wire to the other barrier strip.

Step 5:  Run all of the leads from your solar panels into the large top holes on your junction box.

Step 6: Connect all of the positive wires from your solar panel to one barrier strip.  Then connect all of your negative wires from the solar panel to the other barrier strip.
You will now have one positive bus bar, and one negative bus bar.  Your junction box just helped you to take all of those messy wires from the solar panel, and organize the
into one neat box that not only combines all of the panels together in parallel, but also now gives you two nice neat wires to work with.

Step 7: Connect the new single positive lead to your charge controller, and then connect the new single negative lead to your charge controller.

Step 8: Connect your charge controller to your battery.


Here is a great device to use for measuring the wattage output of your solar panels back into your grid.  It is called the Kill-A-Watt from P3.  This device is usually used to help you determine what appliances in your house are using the most wattage, and to help you get control of your electricity waste in your home.  We have included the original description below so that you can see how useful this tool is – but here is how we use it for our solar panel grid-tie setup.

We use this device in line with our solar panels and our grid tie inverters to measure how many watts, and amps our solar panels are actually producing through our grid tie inverter, and how much energy we are putting back into our grid.  This device is great because it plugs into your outlet, and they you plug your grid tie inverter into it.  Once you switch on the inverter, the Kill-A-Watt, starts recording how many amps, and watts are being produced.  It will even show you how many Kw have been created and over how many hours so that you can really judge the effectiveness of your panels.  We think it is a great device and we have it hooked up to all of our solar panel arrays that are grid-tied.
HERE IS WHAT THE KILL-A-WATT is normally used for:
The Kill-A-Watt allows you to connect your appliances and assess how efficient they are. A large LCD display counts consumption by the Kilowatt-hour.  You can figure out your electrical expenses by the hour, day, week, month, even an entire year. Monitor the quality of your power by displaying Voltage, Line Frequency, and Power Factor.

  • Enables cost forecasting
  • Accurate to within 0.2%
  • Cumulative killowatt-hour monitor
  • Displays Volts, Amps, Watts, Hz, VA, KWH, Power Factor
  • Operating voltage: 115 VAC
  • Max current: 15 A
  • Max power: 1875 VA

You can find these online, ebay, or even radio shack.

Grid Tie Solar Inverter

What is a Plug and Play Solar Grid Tie Inverter?

A Grid Tie inverter is a simple device that takes direct solar panel electrical input, and then steps it up to a pure syne wave that can be pumped into your household grid through a recepticle.  These devices look like AC/DC inverters, and in a way they are, but they are pure syne wave inverters that output AC electricity.  So they take the power from your solar panels, and then pump them into your house grid – allowing you to input the juice you are creating to your own home electrical grid.

There are pros and cons to using these, and in our experience, here are a few things to be aware of when using these devices.
1) When these devices are on, you DO NOT want to unplug them, as you can get an electrical shock.  Since these actually push electrical out of the male plug back into your house recepticle, these work opposite of what you are used to with normal plugs, and you should never touch the male plug from the Grid Tie Inverter while it is on, as it will electrocute you.

2) These should only plugged into a dedicated GFI circuit coming directly out of your main breaker box.  You really should have a shut-off switch between your main breaker and the GFI this is plugged into to completely eliminate this device from the grid in the event of a grid shut-down.  These devices have a safety on them that shuts them down when no grid electricity is detected, but if you have this plugged into the grid, producting electricity during a black-out, there is a possibility that a line-man could get a zap from your device.

3) We have learned that regardless of what the actual watts of power these inverters claim to produce, they are really only half effecient, and you should never try to overload them with more than half their capacity or they will overheat or catch on fire.  So if you have a 600watt Grid tie inverter – expect to only run 300 watts of solar panel juice to it, and expect it only to produce about 300 watts.  This is very important to note, as these have a tendancy to over-heat and shut-down or catch on fire if you overload them.

4) You can stack these devices to try and get more power output from them, but we do not recommend this.  It is best to keep them running separately on their own circuits when using more than one on your grid.  What happens with these units is when they are stacked, they actually become master and slave units, and the slave unit hardly gets any say in the amount of power or output it produces.  The master likes to take over, and they you are overloading that device.  So keep them on separate circuits, and pnly feed them from separate solar panel arrays.


Installing a Grid Tie Inverter is very simple.  Just connect the Red leads from the solar panels to the Red DC Input pole on the inverter, and connect the Black leads from the solar panels to the Black DC Input pole on the inverter.  Connect a ground wire to the ground lead and connect this to a ground terminal on your house.  Then plug the male AC Output plug connection into a dedicated GFI outlet on your house.  ONCE THIS IS PLUGGED IN, DO NOT EVER DISCONNECT IT WHILE THE UNIT IS ON!  Then turn on the inverter.  It will indicate that it is generating power to the grid by the LED lights on the side.  We recommend that you plug in a Kill-a-watt meter between your GFI and inverter to measure how much juice it is pushing back into the grid.

Solar Charge Controller

It has been a while since I have posted any Solar Power articles because I have actually been upgrading the electrical system at my rental property where I am installing the solar panels.  I just got done installing new utility boxes and meters and I really have not had a chance to tie the solar panels into the house electrical system yet.  I am still looking into the best system to use to tie my panels into my utility box.

However, my panels have been up on my roof and I use them at night to run low voltage DC lights in my house and in my garage.  The only problem is that I have to disconnect the system when I am not at home because the panels could over-charge my batteries.  Even when I disconnect the panels, they are still keeping my batteries topped off with the amount of sunlight they are getting.  I just can’t believe how much FREE ENERGY I am wasting by disconnecting the panels!  So how do you avoid this issue and make sure that you are getting the most power you can from the sun?  Get A Solar Charge Controller!

So what is a Solar Charge Controller and what does it do?  A Solar Charge Controller is a device that is installed directly in between your solar panel and battery bank and it helps protect your batteries from overcharging/discharging, and also helps to prevent an overload or short circuit in your system.  They are great for helping you keep your batteries working to their optimal level.  Additionally,  a good solar charge controller can also help to prevent the battery bank from reverse charging a solar panel – acting as a blocking diode if your solar panel system does not have a one-way diode already installed.

Most Solar Charge Controllers can be used with a 12volt or 24volt battery bank system and can handle anywhere from 50 watts to 400 watts of power.  It really depends on the wattage and amps coming out of your solar panels that will help guide you toward a solar charge controller.  There are also two types of solar chargers available –  PWM (Pulse Width Modulation) and MPPT.  I will explain these in another post, but for these purposes, a PWM controller is fine.

Solar Charge controllers are really easy to install and do not require any electrical skills to get into your system.  You simply connect the solar panels to the charge controller, and then connect the charge controller to the battery bank or appliance/lights you want to run.  That easy!

Solar Charge controllers are available for different wattage and amperage (amps) useage and needs.  To determine what size solar charge controller you need,  look for the watts and amps producted by your solar panel.  For example, I have a 45 watt solar panel kit from Harbor Freight on my garage powering some lights.  When you read the box, it says that each of the three solar panels are “Maximum current, 3000 mA. 15 watts max per panel. Peak voltage: 23.57 volts open current”.  So the max power voltage may be guesstimated by dividing 15 watts by 3000mA or 3 amps equaling 5 volts. If wired in series, which they are, they will produce 15 volts with is common for a 12 volt system (wiring in series change the voltage and wiring in parallel changes the amperage).  So I know I need a solar charge controller that can handle at least 15 volts and at least 25 amps.  So I purchased a 30 amp 12-24 volt solar charge controller.  Solar Charge Controllers are easy to find on ebay, and can be purchased for as little as $40.

When looking for features in a solar charge controller look for the following:
1) maximum power-point tracking (MPPT)
2) a low-voltage disconnect feature and load terminals. This makes wiring much easier and allows the controller to disconnect the load from the battery if the battery-charge level drops below a safe level.
3)  a low-voltage cut-off 

Some Models of Solar Charge Controllers:
1) Pro Star

2) Morning Star:
12-volt Sunsaver Model #SS-10L at 10 amp and Model #SS-20L at 20 amp. Use the 20-amp controller for solar arrays in the larger 150 to 200 watt size range, and the 10-amp controller for smaller array sizes.

Grid-Tied Solar System with Battery Backup

Grid-Tied Solar Energy System With Battery

When I first started looking into how to set up a Solar Power system on my home, the system that made the most sense to me is a Grid-Tied Solar System with a Battery Backup.  This system makes sense to me because I can still tap into the electric lines for larger power consumption needs, but I would also have the additional benefit of slowly building a solar power system that wold support my energy use as well as supply uninterruptible power in the case of storms or blackouts.   Another cool feature of this system is that I can still take advantage of net metering and grid connection rebates as my system expands.


So how does a grid-tied solar system work? 
Take a look at the diagram attached to this post to help provide  a visual for the information listed below:

1) Sunlight hits solar panels attached to your roof  and convert sunlight into electricity.
2) This electricity travels through wires to the charge controller, which senses battery voltage and regulates battery charging.
3) The Charge Controller is then conected to a battery bank and the electricity is then used to keep the batteries fully charged
4) The remaining electricity is then transferred to the inverter, which takes the electricity from the solar panels and battery bank (DC electricity) and converts it into the electricity your home needs to run your regular appliances, lighting, etc. (AC electricity)
5) This AC electricity then travels to your standard utility breaker box, and is supplied to your new utility net meter – which then of course feeds the electricity both to your home and to the electrical utility grid.
6) In the event of an emergency (blackout or power loss), your system automatically begins to draw power from the backup batteries and converts it into electricity. The Backed-Up AC Service Panel feeds into the appliances and other electrical needs you deem necessary in the event of power loss.

The main components of this system are:

Solar Panels and Mounting racks
Charge controller
Battery bank
DC/AC Connection/Disconnect Box
Net meter

This is the system I hope to build in my rental property as the final stage of my Solar Power Project House.

How to estimate a Solar Grid-Tie System

As I was researching ideas to turn my rental house into an alternative energy consuming living space, I ran across some formulas that I found very helpful to help me determine what size solar power system I wanted to add to my home. Hopefully this can be a good start for anyone else thinking about doing the same thing.

Step 1:
Find the average monthly electrical use from your electricity bill. This number will be in kWH (kilowatt-hours). Record average monthly kWH electrical use: __________kWH

Step 2:
Multiply this average monthly kWH electrical use by the percentage you want the solar system to produce: __________kWH ie: 1000kWH X 50% = 500kWH
NOTE: most homes consume between 20,000 to 50,000kWH a day on average.

Divide by 30 for the daily output from your solar power system: __________kW

Divide by the daily average sun hours for your location: __________kW 6 in Sun Belt, 4in NE / NW

Divide by 75% to compensate for system efficiency: __________kW

DONE: Take your final kW number, and this is the smallest size system you should build. You can make it bigger if you want to account for margins of error.

Solar Power/Alternative energy House Project

I have finally decided to try and create a living space that is run primarily from Solar Power and Alternative energy sources as opposed to grid power. This idea hit me when one of the upper units of a rental house I have suddenly lost power for no apparent reason.  After a lot of discussion with a few electricians and contractors, the power could only really be restored after we ripped out the walls and ceilings to find the source of the problem – so in my case necessity is the mother of invention.  UPDATE – July 22nd:  $1500 later the source of the electrical issue was an old electrical box that was arcing.  Very bad. I had this fixed because I want to later tied the solar panel system into the grid – so the electrical system needs to be up to par. 

So how do I plan to do this? Well, I have taken into account that converting a house to run strictly off solar and other alternative energy sources as opposed to grid power can be expensive and time consuming. I am looking for the best DIY methods that are both effective and safe. I am also going to be looking to incorporate off-the-shelf products such as solar panels, inverters, batteries, and wind generators to help make this possible. I am also not going to rule out any practical clean sources of energy, such as solar, wind, and propane.

This project is going to be done in steps and I will try to tackle the biggest pressing power consumption issues that occur in our daily lives at home. Phase 1 of the project will be to simply integrate some simple solar panels and use them to power lights in the house.  Phase 2 will be to step-up the solar panel output and put bigger inverters into the house to run standard AC appliances off the battery bank.  Phase 3 will be to tied the system into the grid and try to make money back from the power company during the day!

To start out, I want to install a very basic off-the-shelf solar panel kit on my garage to power some garage lights and exterior lights.  This will be a very basic unit that will be used to practice for the main event.  This will also serve to show how the system works and will help me to scale up to the house.  Right now, here are some of the things I am considering as an initial checklist for the garage install. Since Phase I is really just about using the Solar Panels to light the garage and practice, the list will be small and simple. 

PHASE I LIST OF MATERIALS:  (roughly $800  -$1000 total cost)
Solar Panels – 4 sets of 45watt solar panels (purchased from Harbor Freight)  $450 combined total
Power Inverter – Harbor Freight Power inverter – 700watt:       $100
Solar Charge Controller – Harbor Freight or Morningstar Unit:   $40-$80
2 Deep cycle Marine Batteries:  $120 (walmart)
Automotive battery wiring: $60


Phase 2 will simply be the setup to get the house ready for a solar panel installation.  There is a lot of prep-work that goes into getting a house ready for solar power use, and a lot of this initial equipment is expensive, so I need to break this all down into bite-sized bits.

Phase 2 Material List
Install a Grid-Tie DC/AC Inverter (Looking at a Trace 4024 inverter) (basement)
Install a Trace Ground Fault Protector (basement)
Install a Combiner Box (array) to wire more solar panels to the house and into the battery bank (basement)
Install a breaker box for the solar panels only (basement)
Install a bigger battery bank system coming off the breaker box (battery amount not yet determined – basement)

Phase 3 will consist of wiring the new solar panel setup from Phase 2 and connecting it to the current Utility Breaker Box on the house.  This will tie us into the grid and allow the system to be connected to both the solar panels as well as the utility fed power lines.

Phase 3 Material List:
Certified Electrician
Utility Net Metering Setup
Digital Measuring system to capture input and output

Boost the Solar Panel system to produce somewhere in the range of 780 Watt – 1000 Watts of energy that can be run fully off the grid.  

– I need to set this system up to be a 24 – 48 volt electric system
– The system should produce 2 to 4 kilowatts of usable power on a sunny day.
– Should support a home of up to 3 people.
– System needs to provide enough power for high efficiency lighting, a small TV, DVD or satellite receiver, stereo, computer, dish washer, kitchen appliances including a microwave, hand-held power tools and a 120 volt AC or DC well water pump, and a small DC refrigerator.

Energy Use Considerations:
1) Lighting: I am going to install sky-lights and larger picture windows throughout the house to help light the home better throughout the day. At night, DC Lighting will be used initially, and will be installed into each room from the ceiling as primary light source. 5 rooms of the unit will need to be lit.
2) Power inverter system will be needed to convert DC power to AC power in order to run two computers, wireless internet, television, a radio, kitchen appliances, a microwave, and a dishwasher.  Eventually this needs to be upgraded to run the furnace and washer and dryer as well.
3) Refrigerator – considering the purchase of a propane or solar powered refrigerator.
4) Cooking – convert the gas stove into a propane stove. Oven will not be used in the unit. Could investigate the use of a propane oven if needed.
5) Air Conditioning: I have found some really cool methods for creating a solar evaporative swamp cooler – so I want to try that, but that is not ideal.  I do not have central air, so I will install “whole house fans” and I am also looking into purchasing some of those solar powered attic fans to keep air-flow moving in the home.  Solar Power Air Conditioning units exist and are an option, but they are very expensive.
6) Heating: Right now it is the summer time, so I am not worried about heating the house. However I live in MI, so I have to figure this out soon because it gets really cold here. I am going to start with a system to heat my water using solar energy.  There are also a lot of good DIY solar heater instructions using a solar heated air system I want to try. 
7) Long term goal will be to run each outlet in the house off the battery bank and inverter system and have it powered from solar, wind, and grid power. Longer term will be to dump power back into the grid and make money off it.


I want to purchase 40 100-watt solar panels and attache them to, the roof of the house. Ultimately I want to achieve a 24-48 volt system. I want to be able to divid the solar panels into array of 4 sections, each having 4-6 24V module pairs, depending on the size of that section of the roof. The wires from each module pair will run into a junction box for that section, and from the junction boxes down to the inverter setup that I hope to install in the basement.  The wires from the 4 sections will then go through a ground fault interrupter, through a set of DC breakers and, then finally to the battery bank. I want to eventually install two of the Trace inversters, and so I will need to install 2 more DC breakers, one per inverter between the inverters and battery bank.  The AC input from the  power grid will connect to the inverter, as well as the AC output to the house loads. The inverter will manage the power from both  sources. This will be done so that based on different power demand loads,  power  can be pulled from the panels or the grid to account for the difference. If the loads are not fully using the solar power, the extra juice will be dumped inot the grid, running the meter backwards – and paying me back.

So far that is the gameplan, and this is the first entry to help chronical the alternative power house experiment.  I am going to start Phase I of the project by using some really simple solar panels and hooking up lights, a small TV, and a computer to the system.  I already have 4 sets of the 45watt solar panel kits form Harbor Freight and these should work out nicely for the lights in the house.  I will begin installing this system during the month of July over the next few weeks.
July 2nd, 2010 – purchased Four (4) 45watt solar panel kits from Harbor Freight

July 12th, 2010 – purchased two deep cycle marine batteries and created a make-shift containment box

July13th, 2010 – assembled and installed two of the kits and mounted on back roof.  Connected them to the deep cycle batteries.  Connected light and the house now has solar powered lights in the kitchen and bathroom.  Temporary testing installation only – not permanent, but could easily be done for cabin’s sheds, or garage use.

July 19th – ordered a basic solar charge controller for use with the basic solar panel kit to be used in the garage install.

July 22nd – had to fix the power meters on the house, update the boxes, and have the wiring checked due to a short.

July 29th – received the solar charge controller.

August 7-8th, 2010:  Moved a bunch of stuff in the garage and organized a place that I could use to mount my solar panel conversion equipment and battery bank.  Drew diagrams for the simple garage solar power system. (will add to blog)

August 21st -22nd- installed a basic roof mount system on my garage for the solar panels to mount onto.  Attached two sets of the solar panels to the garage. (I need to update this blog with photos).  Now I need to run the wiring down into the garage and install the breaker box.

45 Watt Solar Panel Kit

45 Watt Solar Panel Kit

If you are looking to get started into using clean renewable solar energy, but you are not sure where to start, I would recommend that you buy a 45 watt solar panel kit from Harbor Freight.  (I am not being paid by them or endorsed by Harbor Freight to write about this product, but I am recommending it because I have used it and still use it). 

So why do I recommend that you go out and buy this kit?  Because it makes it easy to get started learning and using solar panels.  If you have a Harbor Freight location near you and you can check this solar panel kit out in person, you will see that it is pretty durable, easy to set-up, and it can be expanded to provide you with more power if you need it in the future.  The cost also is not bad – roughly $250 if you pick it up in store, a little more if you have it shipped to you. 

With this kit, setup is a breeze, and you can be up and running in about 30 minutes.  This solar panel kit included three 15 watt solar panels that you can string together to get 45 watts, two DC florescent lights, a power converter, a few cords for connecting everything up, and an aluminum frame to mount the panels.

I use this at one of my rental properties to light some exterior lights on a garage, and I am even thinking about using this kit in conjuction with another kit to power the lights of the entire upper unit of my duplex.  I plan on posting some pictures and some video about how to set this thing up and use it in a few weeks as of this posting.

You will need to buy a 12 volt deep-cycle battery and a 300 or 700 watt power inverter (I recommend at least a 700 watt power inverter to run lights and a television and computer).

FREE SOLAR PANELS – how to get them

You often see signs around construction sites that are solar powered, from time to time these signs will get damaged from drunk drivers or rubber-neckers passing through construction areas. Most of the time, the solar panels are still working but the glass above them is shatered so they have less of an output. Typically they still produce about 30 watts of power. The ones that are not shatered produce 60 watts and cost about $200-$300 dollars. Look closely at the signs and you will find a sticker with the phone number of the traffic sign rental contractor. Use your pen and paper to write down this number.

Call the company and ask for the shop maintaince manager or head mechanic and ask him for free damaged panels. If you have kids who enjoy doing experments, have them ask. Most companies love to help kids doing a school or class project. Most all traffic rental sign contractors have free solar panels that have some cracks or slightly damaged when drunk drivers hit the parked sign trailers. They replace them and throw away the damaged ones – and their insurance covers the cost. If they say you can come down and pick them up, you will want to take a big truck or trailer with you so that you can take off of the garbage panels they have with you. I tis best to take all of it, and disassemble whatever you do not need at home. If they do not have any panels or are unwilling to work with you, be nice, and ask them if they can refer to anyone that would be willing to unload some damaged panels. Be on time when you make an apointment to go and see them – and do not skip any appointments you make with them! Thank the shop mechanic with a box of doughnuts and refreshments and he might even call you when he has some more discard solar panels!

Once you get the panels home, test and repair the damaged panels as needed, cracks can be resealed with clear silicone. Wiring can be soldered back together.


Always Be polite when asking for discard parts

Don’t stop on a busy road to get the phone number from a solar sign, as this is very dangerous and you can cause an accident.

Is heating water with solar energy right for you?

The average house spends more on hot water than any other part of their heating bill. On average, 25% of a home’s energy bill is from heating water. If you can implement a system in your home that would allow you to use solar energy to heat your water and transport it throughout your home, it would be one sure-fire way to help you cut down on your energy bill. .

Ideally, you want a south facing roof with a slope of your latitude + 15 degrees. Your solar collector should also have full sun between 9am and 3pm.

When considering a hot water panel setup, you want to make sure that you have panels large enough to supply enough hot water for everyone in your home. A general rule is to get a solar panel that has 10-15 square feet of collective solar area per person in the house. So if you have a home that has 4 people in it, I would recommed that you look at a collection system with panels that cover at least 40 square feet of area to sufficiently supply a constant hot water supply.

These systems, when used properly and installed properly, can help you to shave at least $200-$300 off your energy bill a year. It is important to factor in the amount of shade and the demand for hot water in your home to help you figure out the overall costs and savings.

Now that you know how much these systems can help you save in a year, it is important to note that a typical solar heating system on the market can start anywhere between $1500 and $3000. The systems will generally pay for themselves in about 5-10 years. You can look at the initial price of the solar collector as pre-paying for hot water. There are a wide range of solar water heaters available, so make sure you do your homework and find the system that will work best for your application. You do not want to invest this kind of money only to find that your system is inadequate for your needs.