diy solar

diy solar

Which solar panels to buy?

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Otisd85

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Jan 2, 2020
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I'm looking to build my first solar array for a off grid home I'm building. To start, I'm thinking around 10kw give or take. I'm thinking about used panels just because they're cheaper, but I'm still not sure if that's the way to go. Would either of these be good panels to start building my system with, or is there anything better anyone could suggest? I'm really new to this, and it's still a lot to take in.
The jinko panels are $117 each and the SunPower are $150 each. I don't know yet if either price is negotiable at all.
Thank you.
 

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The panels that you purchase is somewhat dependent on how you plan to wire them and what (exact) type of charger/inverter you plan to use.

Most people will connect some number of panels in series. In series the Voc adds up. One charger might allow up to 150v in and another might allow 250v in. These numbers will limit the number of panels in series and also determine wire size and wire "runs" count. A 60 cell panel will have less Voc than a 72 cell and a 72 cell less than a 96 cell.

Purchasing panels without an end to end plan is not a bad idea, but you will put limits on what you can do with the wiring. There are always limits of course. You just need to determine if "cheap" today is going to add limits that you don't want in the future, which you get your charger/inverter.
 
I'd suggest doing a detailed analysis of your needs including expandability in case you underestimate. That will let you pick an inverter, charge controller and batteries to meet your requirements. Then use the specs for the inverter to figure out what panels and configurations would work given your available space. For example even though I have lots of space next to a barn, the cost of ground mount systems pushed me to buy the highest output panels I could get easily because that reduced mounting costs. If it were on a roof top where mounting cost is much less than on the ground, I would have had more options for lower output panels. Think about how much 10kW of panels weighs, do you have the ability to pick them up yourself and handle them at each end? I also have 10kW of panels and the package they came in weighed 1400#. I ended up buying new panels from a local supplier because they deliver for free and have a power lift gate to lower them. I happen to have a tractor big enough to lift a pallet that size, but if you don't you're going to have to move them one by one by hand. In the end I found that buying new allowed me to get matching high wattage panels, a guarantee, and free delivery from the place I bought them. I bought from CEDGreentech, they're all over the country and mostly deal with commercial installers but are very friendly toward DIYers.
 
Depends on how much real estate you have and how you want to wire them. From my research the 250w panels are the least expensive per watt, but you obviously need more of them to get to 10kw.

10000/250=40x$50=$2000/10000kw= $0.20 per watt
10000/400=25x$117=$2925/1000kw= $0.29 per watt
 
Before you start buying anything, I think it more prudent to perform an energy audit first to actually quantify your needs. I'm not sure that's the appropriate size for you? Can you put together an itemized list of what it is you want to power? I'm assuming that air-conditioning is a goodly fraction of that?

The prices you mention are ok, at around 3W/$, but as "iamrich" mentions, you'll find better deals amongst the 250W panels. Last summer I was getting closer to 4.5W/$ with those. Don't start buying random components till you have a solid plan.
 
I'm have my basement built, and I'm looking to get it watertight and livable to winter in before I start building the upstairs next year if finances allow, it may be 2 years. My demands are unknown at this point, and I intend on having to add to the array once the house is complete. Space is not too much of a concern, but i don't really want the array to be bigger than necessary. I plan on it being a ground mount, possibly mounting it on a shipping container.
 
Otisd85 said:
I'm have my basement built, and I'm looking to get it watertight and livable to winter in before I start building the upstairs next year if finances allow, it may be 2 years. My demands are unknown at this point, and I intend on having to add to the array once the house is complete. Space is not too much of a concern, but i don't really want the array to be bigger than necessary. I plan on it being a ground mount, possibly mounting it on a shipping container.
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I am assuming budget is an issue then. What are you looking to spend and realistically what are you looking to power? A fridge and some lights, occasional microwave? Or are we talking usually home creature comforts (AC, Heater, Water heater, fridge, microwave, lights, tv, internet, etc.)?
 
iamrich said:
I am assuming budget is an issue then. What are you looking to spend and realistically what are you looking to power? A fridge and some lights, occasional microwave? Or are we talking usually home creature comforts (AC, Heater, Water heater, fridge, microwave, lights, tv, internet, etc.)?
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Yes, unfortunately I am NOT monetarily rich. I assume I'm going to spend around $20k on a diy system with charger, batteries, inverter, and what not. I don't want to be cheap where I shouldn't, but I also don't want to pay retail where it's not necessary. Im trying to save some money in the long run while not being reliant on the power company. I'm not really looking for a new hobby, i already have more than I can keep up with. I'm going to try to keep energy consumption to a minimum, but that's going to be a major adjustment for my wife and kids. I want to plan on using creature comforts we're accustomed to, and if it's reasonable maybe i won't have to double the size of the system once we get upstairs.
 
Panels are $0.20 a watt used (80% or more output, likely 20+ year lifespan)
LiFePo batteries (plug and play) are hovering around $300 per kwh
Charge controllers/inverters can be under $1000-5000.

You could build a solid system with 9kw of panels (250wx36), 20kwh of battery (24v, 200ah x4), and 6kw (MPP 3048LV-MKx2) of split phase (120/240v) inverter for right around $10k. Really your only risk is the controller/inverter cost. Panels are panels, you can reconfigure them to almost any controller (especially the lower wattage 250w panels). Batteries are reconfigurable as well so as your needs grow, so can your system. But I am talking all DIY, so if you don't want another hobby that might add cost (installation). Add a small generator (1000w would do it) and as long as you have sun and/or fuel, you are good. With 9kw of panels, even if you only get 80% and 3 hours of sun you are still looking at 21kwh a day of usable power.

The system I built cost me $3000 and has 2kw of panels, 6kwh of battery, and 2400w of inverter. It will power most smaller items, but not big ticket (water heater, washer/dryer, stove, etc.). It will run 1500w of heater and split AC fine and most of the smaller power tools.
 
Your comments support the majority of the thoughts I have, pretty close to what you are suggesting. It sounds like i have more research to do on 250w panels, but most of them I've come across seem considerably older than the higher wattage panels for some reason, and that's part of what's kept me away up to this point. I plan on building what I can myself, and learning as much as I can so I can work on the system when there's issues.
 
Otisd85 said:
I'm have my basement built, and I'm looking to get it watertight and livable to winter in before I start building the upstairs next year if finances allow, it may be 2 years. My demands are unknown at this point, and I intend on having to add to the array once the house is complete. Space is not too much of a concern, but i don't really want the array to be bigger than necessary. I plan on it being a ground mount, possibly mounting it on a shipping container.
Click to expand...
Your main wiring to where you put your array(s) will be a limiting factor. So careful planning on AC, or DC, higher voltage DC, etc will govern your wiring plan and then wire to a size that is large enough for your best guess plus (whatever). Keeping the array close to the house will help on both wiring cost by distance and by size, as the size will go up (somewhat) as the distance increases.

My ground mount with is a mix of "good" and cost effective parts.
 
Otisd85 said:
Your comments support the majority of the thoughts I have, pretty close to what you are suggesting. It sounds like i have more research to do on 250w panels, but most of them I've come across seem considerably older than the higher wattage panels for some reason, and that's part of what's kept me away up to this point. I plan on building what I can myself, and learning as much as I can so I can work on the system when there's issues.
Click to expand...
Mounting cost per panel needs to be considered as well.

There appears to be an effort to keep the current to about no more than 10amps per panel, so larger watts will see higher voltage to keep the amps down.
 
Otisd85 said:
I'm looking to build my first solar array for a off grid home I'm building. To start, I'm thinking around 10kw give or take. I'm thinking about used panels just because they're cheaper, but I'm still not sure if that's the way to go. Would either of these be good panels to start building my system with, or is there anything better anyone could suggest? I'm really new to this, and it's still a lot to take in.
The jinko panels are $117 each and the SunPower are $150 each. I don't know yet if either price is negotiable at all.
Thank you.
Click to expand...
Where did you find Jinko panels? thanks Joe.
 
About wiring distances from arrays to controllers. I'm wiring four 30V panels in series to get about 124VDC. I'm finding that I can run that as much as 130' away from the combiner box with no noticeable voltage drop using 10 gauge wire. I'm utilizing Midnight200 charge controllers, so I'm not anywhere near the 200Voc limit.
 
As some have said, the amount of real estate is a real issue. I have plenty of room, so I started out with 40 of Santan Solars used 250 watt panels at $50 each delivered price at the time. They're good panels, I get about 200-210 watts out of mine. They're in two groups and starting to take up a lot of space, so for my next project I bought 24 of Santan's 370 watt REC panels, much newer tech, brand new, high efficiency. They're the same width, only 5 inches longer and put out a lot more power. They work out to 50 cents per watt deliverd, versus 25 cents for the 250 watt panels.

If you can spare the room, I think it's hard to go wrong with a couple of pallets of the 250 watt panels. Frankly, panels are just dirt cheap these days, compared to the $4-$5 per watt I used to pay, and I have serious concerns about their ever being so cheap again, so my last purchase was party a hedge against inflation. As we've all seen in the last couple of years it doesn't take much for prices to soar overnight. Having them on hand gives me a warm fuzzy feeling that's worth quite a bit...
 
Joe BoyKey said:
Have no clue, started with 6 395w and 1 spare, need 1 more to have 2s4p and more watts, Joe.
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Why 2s4p? The 395w panels I'm getting (Bi-facial Half cut from Signature Solar) would be 98v and 39A. That seems backwards to me. Most want High volts low amps like 4s2p. That would be 196V 19.4A. That would allow smaller wires and match more Inverters. Just a thought.
 
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