# Planned Hybrid Solar Setup



## DWBayless (Jul 22, 2015)

2 small Harbor Freight solar panel kits live in my shed, charging my power tools, and running a few lights during an outage. We live far enough back in the sticks that outages are common, and fairly long-lasting. We do have a baby generator that is sized to be able to run the refrigerator, but I donât like running it all of the time, and my electronic devices donât like the power it produces, so it is time to build a small hybrid system. 

The goal for the system is that it should operate our computer network, lighting, communications equipment, a couple fans, a TV, and a laptop. Maximum normal usage has this at about 1.8KWH/day. If we have a day or two without much sun, we can switch back to the grid, to preserve as much charge as possible for outages. When an outage does happen, we can shift more loads to the system, and certainly will be able to handle more during the summer, and when the grid is down, weâd still have the generator. 

This is a budget build, so much of the equipment isnât premium. Iâm planning on building a more robust system when we build the new house. This system will be repurposed to a studio/guest cottage that we are building afterward. 

NASA says we get 2.91KWH/square meter/day at this location during the darkest month of the year, so Iâm figuring on the following:

The system will be 24 volt
- 3x Suntech STP275 solar panels - wired in series for 825 rated watts. I had considered Renogy 100 watt panels because they are smaller, lighter, easier to handle, and are free shipping. Even with the extra freight charge, the Suntech panels are are less expensive, and will require less supporting hardware - wires, mounting brackets, etc. If I miss the Suntech sale, there will always be something similar on the market. 

- Epic Solar Tracer 4215BN MTTP Charge controller. 

- 4 Duracell Ultra SLIGC125 golf cart batteries. Series parallel for 470AH. These are Johnson Control made units. These are not RE batteries, but they are incredibly inexpensive. The system will spend most of its time above 80% SOC. The batteries are available locally, so no shipping. Besides, if I make any terrible mistakes, whilst learning to live with solar, Iâd rather do it on $520 worth of batteries, rather than the more expensive ones. 

- Power Bright 600W pure sign wave inverter. Again, not a premium company, or terribly powerful inverter. But sufficient for everything that weâd likely run off of AC at once. Iâm considering upgrading to a 1000 watt unit. This would give us extra capacity that we'd be more likely to use in the summertime, but likely at the cost of a bit of efficiency at lower draw rates. Probably worth the $.

-Blue Sea systems fuse block. Circuit breakers are more modern, less troublesome, and make more sense, but Iâm an old fashioned kind of a guy. 

I plan to run everything that I can off of either 24V DC (lights), or via DC-DC converters. These solid state units are more efficient than inverters. 

Thoughts? I'm not the best in the world at making diagrams, but I'm a visual thinker, so gave it a shot:


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## homestead-hubby (Jul 9, 2015)

Well it sounds like you have done some homework on this one... It's not a truly remarkable setup though.... The worst part of building with low cost parts is the low quality of a number of the products.... However if you want to then by all means do it.... The only way you can test out the concept is to put it use.... Me personally I want to keep most of my needs at 12vdc

I would rather have a refrigerator that is A.C. D.C. and natural gas.... Computer systems can and do run well on DC current.... Among much more... I have to do something so I will comment more later


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## DWBayless (Jul 22, 2015)

It is true - budget stuff is generally budget for a reason. None of this stuff is exceptional, but it is a non critical system. If quality control makes me go through the return process a time or two, I can deal with it. Saving cash for the house build. 

I'd considered 12 volt, since I don't have any long wire runs, but it would limit me to less than 500 watts of input, on this controller. This gives me more room for expansion. 

the Macbook will be easy to run off of DC. The two desktops we have are iMacs. Opening those suckers up is next to impossible, so I'll be running them through the inverter. The refrigerator I have is AC only, uses about 1.1 KWH/day during the summer, about 950 watts a day during the winter. That is about a quarter the amount of power the old one used.


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## wy_white_wolf (Oct 14, 2004)

DWBayless said:


> ...
> - 4 Duracell Ultra SLIGC125 golf cart batteries. Series parallel for 470AH. These are Johnson Control made units. These are not RE batteries, but they are incredibly inexpensive. The system will spend most of its time above 80% SOC. The batteries are available locally, so no shipping. Besides, if I make any terrible mistakes, whilst learning to live with solar, Iâd rather do it on $520 worth of batteries, rather than the more expensive ones.
> 
> - Power Bright 600W pure sign wave inverter. Again, not a premium company, or terribly powerful inverter. But sufficient for everything that weâd likely run off of AC at once. Iâm considering upgrading to a 1000 watt unit. This would give us extra capacity that we'd be more likely to use in the summertime, but likely at the cost of a bit of efficiency at lower draw rates. Probably worth the $....


You made a mistake in calculating the batteries. They are 6 volt so it'll take all 4 of them in series to get 24v. So you bank will only be 235AH. That means you battery bank will be a little undersized. You should only use 20% of the capacity in a day. That would be 1124WH and your planning on 1800WH. Charge rate with your array ends up right at C/8. so right on the high side but workable.

Also go with the larger inverter. I think if you stay with the 600W one it'll have a hard time handling the startup surge of the frig.

Other then that it looks like a decent setup.

WWW


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## DWBayless (Jul 22, 2015)

wy_white_wolf said:


> You made a mistake in calculating the batteries. They are 6 volt so it'll take all 4 of them in series to get 24v. So you bank will only be 235AH. That means you battery bank will be a little undersized. You should only use 20% of the capacity in a day. That would be 1124WH and your planning on 1800WH. Charge rate with your array ends up right at C/8. so right on the high side but workable.
> 
> Also go with the larger inverter. I think if you stay with the 600W one it'll have a hard time handling the startup surge of the frig.
> 
> ...


Oh, yes! Absolutely right. Thanks.


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## homestead-hubby (Jul 9, 2015)

wy_white_wolf said:


> You made a mistake in calculating the batteries. They are 6 volt so it'll take all 4 of them in series to get 24v. So you bank will only be 235AH. That means you battery bank will be a little undersized. You should only use 20% of the capacity in a day. That would be 1124WH and your planning on 1800WH. Charge rate with your array ends up right at C/8. so right on the high side but workable.
> 
> Also go with the larger inverter. I think if you stay with the 600W one it'll have a hard time handling the startup surge of the frig.
> 
> ...


Good catch... I didn't even look at that till you mentioned it..


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## homestead-hubby (Jul 9, 2015)

DWBayless I will write more tomorrow... I'm off to bed... The old lady says so... She's the boss... But yes that setup would be better with a larger inverter........ might want to invest in a battery bank of some of the deep cycle 12v batteries or something.... 

I'm personally not a fan of being grid tied so I'm a bit biased against setting up to be grid tied... Okay I gotta go... I'll write when I am a bit more coherent... Sleeping pills kicked in...


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## DWBayless (Jul 22, 2015)

homestead-hubby said:


> DWBayless I will write more tomorrow... I'm off to bed... The old lady says so... She's the boss... But yes that setup would be better with a larger inverter........ might want to invest in a battery bank of some of the deep cycle 12v batteries or something....
> 
> I'm personally not a fan of being grid tied so I'm a bit biased against setting up to be grid tied... Okay I gotta go... I'll write when I am a bit more coherent... Sleeping pills kicked in...


My first considered COA was a 12V system, 470AH. When I decided when I'd decided to go 24V, I indicated that I'd need double the batteries on my system worksheet, and my estimation of what I was planning to power with the system. It didn't stick in my grey matter, I suppose. I got stuck on 2X2. I guess that is the risk of system planning during insomnia moments. . 

I'm thinking about heading out of Budgetsville, and upgrading my purchase to 1 string of 4 Surrette S-480s. That would give me 370AH. Cycle depth would stay in the top 20% most of the time, and charge would be just slightly slower than C10 rate, and there would be no parallel strings. Cost would only be a couple hundred more than the budget batteries. It is a bit less capacity, but probably much longer lasting. 

With decent batteries, and with an abundance of caution, I'm also thinking of upgrading to a Midnite Classic 150 controller instead. I have some misgivings about budget controllers that I just can't quite get past. Every time I buy budget equipment, it ends up costing me more in the end, this applies to everything from consumer electronics, to cars, rototillers, etc., so probably applies equally as well to charge controllers. In that same spirit, I'm thinking of a more substantial, higher quality inverter/charger also, instead of the Power Bright unit. 

My system isn't going to be grid tied, for various reasons. Among them are the number of outages here, and the added administrative and technical complexity that grid tie involves. 

I'd like to get away from connecting the new house at all, or if I do connect it, just use the grid in place of a generator, when absolutely necessary - mostly for idealogical reasons that make no immediate financial sense. It just isn't practical to do that in this house. If everything goes to plan, we'll have the new house up and habitable in 2017, and this wheeled box will be moved down the road.

With this system, I'm going to take several circuits off of the grid; circuits that I consider essential, or highly desirable to have operate during outages. In principal, it is more of a backup that attempts to use as much of the power that is produced as possible. 

I appreciate all of the input. I'm pretty sure you folks have talked me out of a few long-term-high-cost decisions regarding my attempts to make an inexpensive setup.


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## homestead-hubby (Jul 9, 2015)

I had just finished typing a response to this and everything and even sent it and I see nothing.... I can't even tell if it posted


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## homestead-hubby (Jul 9, 2015)

I guess it didn't... ----.... All the words and I can't take the time to type it all out again


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## DWBayless (Jul 22, 2015)

homestead-hubby said:


> I guess it didn't... ----.... All the words and I can't take the time to type it all out again


Every now and then, my computer decides to do that to me. Not fun.


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## wy_white_wolf (Oct 14, 2004)

DWBayless said:


> ...I'm thinking about heading out of Budgetsville, and upgrading my purchase to 1 string of 4 Surrette S-480s. That would give me 370AH. Cycle depth would stay in the top 20% most of the time, and charge would be just slightly slower than C10 rate, and there would be no parallel strings. Cost would only be a couple hundred more than the budget batteries. It is a bit less capacity, but probably much longer lasting.
> 
> With decent batteries, and with an abundance of caution, I'm also thinking of upgrading to a Midnite Classic 150 controller instead. I have some misgivings about budget controllers that I just can't quite get past. Every time I buy budget equipment, it ends up costing me more in the end, this applies to everything from consumer electronics, to cars, rototillers, etc., so probably applies equally as well to charge controllers. In that same spirit, I'm thinking of a more substantial, higher quality inverter/charger also, instead of the Power Bright unit. ...


 If this is your first system, I'd advise going with cheaper batteries. Seems everyone destroys their first set learning how to properly maintain them.

Upgrading the charge controller is a good idea. The midnight will do a better/more dependable job.

I prefer to keep the inverter and charger separate. Just want them separate so if something does go wrong it's easier to fix and can still keep the system partially operational until replacement parts arrive.

WWW


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