Solar Power Shed Project

3RRL · Aug 25, 2006

Some of you may recall this thread Solar Power Shed where I built the shed. This is a continuation and will show the progress we're making. After much delay, we finally got the electrical materials in and started to install them.
Here is a picture of some of the wires that are going to be used to hook everything up. It's not all of it though.

Then there is the conduit and pvc that we will use to bury the wires in. Again, I'm sure we're going to get more as we start to pull the wires. Also shown are one of 6 big battery trays in case of leakage. It has been quite an experience working with the solar contractor. You can't believe how much their is to learn. Plus it's very exciting realizing that we will be making our own power...completely off grid...no electric bills ever. (other than maintenance)

Timber · Aug 25, 2006

I'll be very interested in this. I have been looking into putting up a solar array on my house because it is a perfect candidate for this project. I will stay on the grid but we have been talking about it for a couple of months. This is something I have planed for next summer. My home is mostly electric and it will be my way of dealing with the oil energy problem

3RRL · Aug 26, 2006

Indeed this is interesting considering I don't know a darned thing about it, but I am learning. I'm by no means an electronical engineer so bear with me as I try to explain the system.

Including buiding the power shed and the 20kW standby generator it will be approaching $100,000. There will be 2 Watson 225 dual axis trackers that will hold 12 Sharp 200w modules each. They will track the sun from dawn to dusk to allow maximum photovoltaic action to occur.

This is all the power we will have...totally off grid and never an electric bill except battery change over about every 10 or 15 years and normal maintenance of the system. (mimimal) There will be a "back-up" 20kW generator to help charge the batteries in the event they don't store enough energy to run the house and shop. The system is designed to keep the generator time down to the very minimum...maybe having to kick in approximately 10 days per year or so. We wanted the system to be large enough to keep the generator run time down to reduce propane usage. It will exercise itself automatically every week.

3RRL · Aug 26, 2006

There will be no conduit in the slab. The wiring will enter and exit the shed in 2 places to and from 2 Outback MX60 Power Systems. They will be placed in PVC underground running to the house and the other to the barn and machine shop. There is a cut-out in the concrete slab on the opposite side I showed that allows the wiring and pipes to enter and exit the shed, then run down into the ground. There are no overhead wires or poles allowed in our area....everything must be underground.

The system to the house will be 14.4kW 240V AC (48V DC inpput). The system to the barn and machine shop will be 7.2kW 240V AC. (The one for the house has 4 Inverter power panel and the one to the shop has 2 Inverter power panel) The 2 systems will have the ability to "cover" for each other (seamlesss) in the event one fails. Included also is a computer controlled Remote monitoring system with battery back up. It has programmable AUX output that can be used for load diversion and utilizes a 5 stage charging system. According to the Solar contractor, it will do everything except wipe my butt. Ha ha...

How many watts of solar panel power will be installed and what type of batteries? Total Solar power input power on this system is 4800 Watts, 71 Volts @ 84 Amps. Instead of going with 32 Surette S-530 6V batteries, we went with the more expensive (16) Surette 12-CS-11PS 12V batteries. They have a much longer life span than the 6V, up to 15yrs and the warranty runs for 10yrs (instead of 2 yrs.)

The shed will have shelving to hold the batteries off the ground contained in Spill Containment Trays. They will have 96 Water Miser battery caps for hydrogen recovery reducing maintenance. Finally, there will be a partition separating the batteries from the generator and the Outback MX60 Power Panels. The battery compartment will have two electric power vents.

Here's a picture of the schematic...I hope it's clear enough to read???

3RRL · Aug 26, 2006

Well, those batteries are pretty hefty. I think they weigh about 272lbs each. 503 Amphr @ 100hr lead batteries. They store enough energy to run the house and machine shop but it's all DC. Therefore, the DC has to be converted to AC via the inverters. (and they are expensive) These inverters will put out a pure sine wave (not a "square" or "modified" one) which makes the AC electricity useable to run delicate electrical instruments such as computers, monitoring systems and some of my digitized measuring equipment in my shop.

The whole idea about sizing the system correctly is to reduce/eliminate the generator from having to come on. It will run off propane and propane is another commodity that may go up in price over the years like gas has. By being able to store enough energy in the batteries, we may be able to do this.

To give you an idea, when we first looked at designing a sytem, propane was 98¢ a gollon. In our area it's now $3 a gallon! If it keeps going up it will have an impact on our fixed retirement income. So that's why we want the generator to run only on emergencies and not plan on it "feeding" the system on a daily basis.

Here are a couple of (not very good) pictures that show the shelves and 12V Surette 12-CS-11PS batteries. You know Loretta and I built a dividing wall to separate the batteries from the generator. This is on the battery side of the shed.

There are 2 large shelves on each side of the shed and they each hold 4 batteries. We increased the system to 16 of these huge batteries instead of 12 for additional stored power. Well. each battery weighs 272lbs!! So the shelves are re-enforced and on roller bearings so they can slide out for servicing. The batteries will be cabled together and then hooked up to the two Outback Power systems.

Here is a picture showing the trays on the other side and a glimpse of the Sharp 200w modules. Everything is all "packed" in there tight for storage when we're not there.

3RRL · Aug 26, 2006

BTW, the solar contractor and I laid the panels out to test them and provide 100% rated output!!! The sunny California weather is good for something.

We decided to buy a Cummins GGDB20 (20kW) It is liquid cooled and runs at 1800rpm on propane. The generator can run the household and will be wired up so that when there is an immediate demand (from the house or shop) it will send power that way. It will also start to charge the batteries until they get charged full either by the generator or the through the photovoltaic panels mounted on the solar arrays. I'll probably have to fill them with distilled water. But that's what the hydrogen recovery caps are for...to minimize maintenance. And the Power Vents are to keep the area ventilated so I don't blow myself up when I go in there smoking a stogie. Ha ha.

The batteries are pretty expensive and list at $990 ea but My cost is $688.22 each. So that's what we'll be looking at to replace them every 10 or 15 years. However, these also have the 10 year warranty so it will be important that they fail every 9-½ yrs so I can get them replaced under warranty. Not only that, but as newer technology appears regarding battery mediums, they may reduce in price years from now. The flip side is I may be dead by then???hahaha so who cares.

Here's another picture of the rest of the batteries.

3RRL · Aug 26, 2006

So in the mean time, while my contractor is wiring up the Outback Power Packs and electrical stuff, my job is to dig a trench from the power shed to the homesite. Although the earth was very hard right here by the shed, being mostly decomposed granite, the trenching got easier as I got closer to the rocks. My contractor had a ditch witch but could not get through some of the many large rocks that were in his path.

So I start here.

The homesite is over by those rocks at the end of the picture, but the trench will not go that far yet. We will only dig it about 100' for now. Eventually, I will also need a trench that goes over to the barn/machine shop and a short one for the propane tank to the shed.

EddieWalker · Aug 26, 2006

Hi Rob,

Sure is an ambitous project. At first the hundred grand sounds like allot. If you spend $300 a month on your electric bill, it would be 30 years until you broke even. Then I remembered a friend of mine got a quote of $100,000 just to run power to his future home site, and that was only if he could get permision from the other property owners to cross there land.

I don't know anything about it either and appreciate you taking the time to post what's involved with all of us. I am curiuos about the cost of the materials. No including the shed or labor, what do all the parts cost?

I'm also curious about how much power you actually get from the system. Not using the generator, how many amps do you have? Do you have 240 volts, or is it just 120? Does it drop when the sun is down or on clowdy days?

Thanks,
Eddie

3RRL · Aug 26, 2006

EddieWalker said:
Hi Rob,

Sure is an ambitous project. At first the hundred grand sounds like allot. If you spend $300 a month on your electric bill, it would be 30 years until you broke even. Then I remembered a friend of mine got a quote of $100,000 just to run power to his future home site, and that was only if he could get permision from the other property owners to cross there land.

I don't know anything about it either and appreciate you taking the time to post what's involved with all of us. I am curiuos about the cost of the materials. No including the shed or labor, what do all the parts cost?

I'm also curious about how much power you actually get from the system. Not using the generator, how many amps do you have? Do you have 240 volts, or is it just 120? Does it drop when the sun is down or on clowdy days?

Thanks,
Eddie

Eddie,
I'll try to answer best I can, but remember that I am no expert on the system. As to your first paragraph, you may remember I got a quote from SCE to install the power lines from the nearest pull box to my homesite. The cost is $24 per linear foot. On top of that, everything must be underground, so to trench it and conduit that is an additional $25 per linear foot, a total of $49 per foot to get it to my place. The nearest pull box is 4,000 feet away from my homesite....and the trenching was quoted WITHOUT consideration in case they hit a huge rock. With that in mind, spending $100,000 is already a savings of $100,000 right out the get-go.

Material alone for everything excluding the generator, shed and labor is approximately $70,000. But I am getting state of the art compnents and monitoring systems, as well as the best and biggest solar panels that are mounted to computer aided dual axis trackers.

I will get both 120v and 240v with just under 100amps when both systems are engaged. There was an added cost for separating the shop and the house but the safety margin and dependability increased, as they cover for each other. One thing I didn't know is that even on cloudy days the photovoltaic cells (solar panels) accumulate energy...just not at the maximum rated power. At this point, the Sharp 200 panels should fill the battery pack in about 4 hours of bright sunlight, but may take longer to fill on cloudy days....but it will still fill them.

If ever they don't produce enough energy, or the battery level drops too low, the standy by emergency generator will kick in and 1) start to charge the battery pack and 2) provide energy to the ouse or shop. That's why we got a 20kW generator so it can do both at the same time. The battery draw will be just over 7kW to charge so that leaves 13kW to run the house during that time. We expect the generator to kick on only about 10 days per year...we'll see if that turns out correct or not.

3RRL · Aug 26, 2006

Well, it became kind of a friendly race between the two of us...each checking on the other's progress. Like I said, the first part of the trench was REALLY hard digging! But I managed to get it about 30" deep for the first 8 feet where the propane line will lay in the same 18" trough with the electric cables. The rest I dug 24" deep for the electric lines only. It took a long time to dig this 10 foot long trench in that hard stuff.

Meanwhile, the solar guy had installed the Outback Power supply that feeds the house. He had it mounted to the wall and it's ready to wire up to the batteries and generator now.