From Shed to Home.

A story about how solar power was added to a shed, and grew to power much more.

My goal was to at least provide power to a shed that had no electricity in it. The project grew over time, and it ended up powering my home office, and much more, too.

The original plan was to make the system a battery based one. This would allow for power during an outage, and eliminates the worries associate with connecting with the Power company. By charging batteries, and using the batteries to provide the power, It would cost me more up front, and be slightly more complex, but it would begin to cover one of my major worries ... power outages.

So, for a battery based system, I would need a Solar Panel ( PV ), Charge Controller, Battery and Inverter.

The Solar (Photo Voltaic ) Panel would create DC power from the sunlight

The Charge Controller would take the wildly veritable DC power from the Solar Panel, and use it to keep the battery properly charged.

The Battery would store the energy so that it could be used at any time, and allow for occasional heavier loads if they were needed.

The inverter would take the DC from the batteries, and convert it in to standard 120v Household AC current.

Inverter: I started with a Xantrax 1000w inverter.Got mine at a significant discount at the time, less than 500$ Looks like they are running at nearly 800 or more right now. This one is 12volts input, so I need to make sure my battery bank matches.

You can find similar models today located here: Amazon

This one is much better, it includes an automatic transfer switch: AltE Store

Solar Panel ( PV ): Next, I purchased 1 Evergreen 170 watt panel. At the time it had great low-cost-per-watt. The current models are at an even bigger savings, and have higher wattage ratings. Today's comparable model is at least 180 watts. At this size, currently, you can get panels at about 3.33 per watt, or around 600$ This one is 18 volts, so I need to make sure my Charge Controller matches.

AltE Store

Charge Controller: I then purchased an Xantrex MPPT Controller. This particular model is designed to maximize the input power from the 18 volt panels, and constantly track and use as much power as possible to maintain the batteries at optimum charge state. The MPPT stands for Maximum Power Point Tracking, and is the best type of controller to purchase if you intend to use larger panels. This matches my 18v panel and my 12volt battery.

You can get them for around 540$ here: AltE Store

Battery: Next the battery I chose was a Deep Cycle Sealed AGM ( Absorbed Glass Matt ) and is designed for 'no maintenance required'. Perfect for me. :-) This model is MK 8A31 and can hold 105 amp hours each. This translates to about 105*12= 1,260 watts for 1 hour or about 52 watts continuously. The reality though is that you want to use only about 20% of the battery between full charges to get max life, so this one battery only gave me about 10 watts continuous. But since I started only using it occasionally in the shed, I could easily get over 100 watts out of it for the short uses. You can get them here: AltE Store

Then the smaller pieces which included Disconnects, and a Combiner Box.

The first panel was installed by just leaning it up against the shed. The wires were run under the shed up in to it and connected to the charge controller nailed to the wall. The battery was set on the floor underneath the charger, and large alligator clamps were used to connect the charger and the inverter. The inverter was hung on the wall beside the charger and a lamp was plugged directly in to the inverter. This was how it started .... but it grew.

After the one panel was installed, the project evolved to provide power to the back yard and garage too.

Purchased second panel and top of pole mount.

Pole Mount: I went with a top of pole mount large enough to hold 4 panels, hoping to some day having two of them installed. The top of pole allows for easy tilt orientation, giving you the chance to better optimize solar collection during different months in the year. In the Summer, the sun is nearly straight up, but in the winter it is much lower on the horizon.

You can find this one here: AltE Store

Used rails from pole mount to do a much better temporary ground mount.

Here are the two panels installed and pointed to the Solar South by South West. I had to point it more towards the West due to compensate for the heavy tree line that blocks the eastern Sun up to around 11:30 am to 12:30 am. I'm still trying to convince my wife that topping the biggest trees just east of the panels, will not look all that bad, and that it will give us a couple of extra solar hours or power.

Now its time to clean up the wiring, and make doubly sure that the ground is good, and the disconnects are all labeled and functioning well.

The first revision of the wiring is completed. Now, at this point, I have two batteries for a total of 210 amp hours.

Kept growing, and purchased two more panels. 180w Evergreens. and 2 more batteries. The panels are still on the ground, and the so called temporary mount has been in play way too long. But, I'm now up to 700 watts of PV, charging 420 amp hours of AGM batteries.

I finally ran wiring under ground to put power in to the Garage, and decided to keep going, so wired up in to the attic, and down to two dedicated / isolated receptacles in the house. This gives me a fully isolated ( not connected to any existing household wiring at all ) circuit that provides emergency AC power on demand.

I Added Solar power Vent fan to Solar Shed .... to help keep it and the battery bank cooler during the summer.

Fan: Sometimes my shed would get up to over 130 degrees f on a hot summer day. The main problem was that the vent on the shed just didn't allow for much in the way of air flow. I went to Home Depot and picked up a solar power attic fan. Home Depot

You can get a much better version here: Alt E Store

Put the AGM batteries in to an enclosure. Not a very good picture, but its the gray box on the floor. Since the batteries are AGM, I don't have to worry about outgasing or venting, but the enclosure does include some air vents on the sides.

Enclosure: It has room for 6 batteries, and keeps them safe from accidental contact or damage. You can get one like this here: AltE Store

Finally time to begin the pole install for the array top of pole mount. I'm tired of seeing the bottom panels contacting the ground, and the fence keeps throwing shade on them in the evenings. This temporary install has got to be fixed.

I'm going to be moving the excess dirt to beside the shed to help with the un level rear access, so I got a new John Deere x300 and a Johnny Bucket Jr to help with the gravel and dirt moving. :-) You can find the Johnny Buckets for most lawn tractors here: Johnny Products. The provide powered lift and Dump. They do a wonderful job of transporting material. And even allow you meter (evenly spread) out the material as you dump by slowly increasing the dump angle.

Started moving the gravel and top layer of dirt. This was a slow but easy process. I was able to use the bucket Jr to dig in to the dense, compact clay to about 1 foot down. At that point the hard dry clay and the angle became problematic, so it was time to get out the post hole diggers and shovel.

The actual digging the hole for the pole, required some help. I managed to get the hole to about 4 foot by 2 foot by about 2 foot deep, before I 'yelled for help'. Clay is very dense around here. It takes more youth than I have. But, with the extra man power, The hole got to the desired 4foot by 3foot by 4 foot deep.

The hole is complete, the pole has been dropped in to place, rebar has been put through the pole, and fastened in to a cage around the pole. It has been plumbed and anchored in to place. Its time for the concrete.

The concrete has been poured. It took about 1.5 cubic yards. This seems like an over kill install for just 4 panels, but I wanted to make sure it met the guidelines to support a minimum of 90 sq ft of panels in an over 125mph wind. Just in case I add a larger mount and more panels later.

The top of pole mount and main rails have been installed. It is oriented towards the south by south west sky, where it gets continuous sun from about noon to 4pm ish (winter) to 6pm ish ( summer) .

The Panel mounting rails have been installed. Its time for the panels. I got several tons of crusher run delivered to replace what had been moved, and to cleanup the damaged area. The x300+bucket jr saved my back on putting the rock in place!

The Panels are installed. I had to purchase and installed an additional 110w panel to 'balance' the array pole mount. My wife was not pleased with the hole in the middle of the 4 panels. And I was not pleased with the top of the pole being fully exposed, plus, it looked like 'lost opportunity'. :-)

Extra Solar Panel: CTI-110 110W Its dimensions were near perfect to fit in the space between the other panels, while still leaving an air gap to relieve wind pressure. It was also cosmetically similar to the existing Evergreen panels. This panel is 12 volts instead of the 18 volts that I have been using, so I can't connect it to the same MPPT charge controller. But no worries, I'll just get an inexpensive PWM controller to connect it to instead.

These currently run at about 580$, and you can get this panel here: AltE Store

Extra Charge Controller: Morningstar Sunsaver Ss-10 . These charge controllers a very inexpensive and extremely easy to install. You can get them here: AltE Store

The second revision of the wiring is competed. Now includes an additional small PWM charge controller to help utilize the extra 110 watts added to the array. It now also includes another 210amp hours in the battery bank, for a total of 810watts from the PV array, and 630 amp hours in the battery bank. It also has a much larger disconnect box that allows me to do a much better job of routing the wiring, especially to and from the batteries. I also added a 'meter' to monitor consumption of power generated. I still need to add a monitoring device, and move the cc battery wires up in to the disconnect box, instead of a direct run.

Disconnect/ Enclosure: MNDC125. This box is much larger than the original, and it allowed me to put all of wiring in one clean and safe spot. You can get one like this from here: AltE Store

Power Meter: GE Solar KWHR Meter. This one was for the fun of it. I like the looks of having a good old fashioned KWH meter turning to show that I'm using real power. :-) You can get one here: AltE Store

Here is a rough drawing of the project:

I Ended up powering:

• Shed receptacles
• Garage receptacles
• Back Yard receptacles
• Sprinkler system
• DSL internet router
• Laptop
• Telephone
• Light

Using about 1.5 kilowatt hours per day, and charging, back in to the bank, up to 3 kilowatt hours per day.

Normally allowing for at least up to 3 or 4 days of usage during extremely cloudy weather, and continuous usage otherwise.

Using the National Renewable Energy Laboratory's PV Watts Calculator at: http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/

The following results appear support my observations:

This was a lot of fun, and I learned quite a bit in the process. Mostly I learned that I still need to learn more! :-)

Things I did right:

- Got a certified electrician involved to go over all of my wiring to be sure it was safe and to code.

- Had fun.

Things I did wrong, so you don't make the same mistakes:

- Started out with the inverter. This demanded a 12 volt system. A 12 volts system is fine, but it limits what you can do with batteries. On a 12 volt system you want to stay at three or less 12 volt batteries. Makes it harder to grow. consider starting out with a 24 volt system instead.

- Originally undersized the wires from the batteries to the inverter. Melted the plastic covering when I plugged in a high amperage shop vac. Be sure to always make sure wires are appropriately sized.

- Bought 1 panel at a time. This wasn't really a mistake, since I wanted to do this slowly and as money became available. But, It cost a lot more this way. Each shipment had as much as a couple of hundred extra dollars added to it due to freight shipments. If you are going to do this yourself, try to plan your shipments to reduce costs.

-Many little things that were easily corrected. But ended up costing more in the long run.

-Forgot to take pictures of many of the steps.

So, as of now, the project is 90% complete and fully functional.

My recommendation: If you want hands on fun, do something much smaller, and get a certified local installer for your big project. They'll do it right the first time ... and cheaper too!

Updated on: 09-13-2009