Cooljerk
New Member
I'm sorry if this is a little too broad of a topic, but I've read through all the FAQ and have been doing homework here for the past several weeks and I just want to lay out my entire plans to make sure i'm not missing anything before I start throwing money into this project. A bit of background -- I've built myself a 120 sqft tiny home outside of Houston, Texas on a plot of land I own. I want to do an off-the-grid setup and bring my cost of living down, and a big component of that is Solar Energy. I work from home as a computer programmer, so my energy needs are a bit diverse.
Long story short, I've calculated that, with the equipment I have to do my work, I need a budget of about 4800w per day to run my development computer and some other necessities. A friend of mine in the area converted his garage into a home office and runs it off of solar power (and he also warned me how deep of rabbit hole this can all be, haha), and he gets away with a 4800w system, so that's what I've targeted.
What I'd like is a system where I can use solar panels to charge batteries to provide this 4800w daily. Ideally, I'd like to start with something at 4800w initially, then grow it with redundant batteries for prolonged periods of rain, but for right now, I'm concentrating on having a single battery system. My friend recommended I look into server batteries as they can be had at good prices here in Texas because, while they're nearly impossible to ship cheaply, we aren't afraid of driving 200 miles in this state to pick up something. And, low behold, there's a place in Dallas selling server batteries that seem like they're what I need: https://signaturesolar.com/all-products/batteries/server-rack/eg4-lifepower4/
My plan is to get one of those 24V 200aH batteries, which would provide me a capacity of 4800w if I've done my calculations correctly. That would run me $1250.
My worst-case peak solar hours by month according to a calculator site are:
Jan: 4.08
Feb: 4.27
Mar: 4.89
Apr: 5.48
May: 5.7
Jun: 5.67
Jul: 5.63
Aug: 5.82
Sep: 5.6
Oct: 5.33
Nov: 4.57
Dec: 3.74
So I'm doing my calculations based on an average of 4 hours of peak sunlight per day (since I can skirt by with less power in the winter).
I've looking into buying used Solar Panels from this place in Dallas: https://beenebrothers.com/product/ja-solar-315w-solar-panel-used/
That's a 315w solar panel. As I understand it, that means the solar panel can produce 315w per hour at peak sunlight, so at 4 hours of peak sunlight per day worst-case scenario, a single panel is producing 1260w. So I'd need 4 of those panels to produce the 4800w I want my battery to hold in one day? Is that correct? 4 of those panels at $60 each would be $240.
Assuming I get the number of panels I need, I'm next looking at an inverter. I need it to be the size of my solar array, so the inverter would need to be 4800w as well, is that correct? I've been pricing them, and they look to run at about $500, does that sound correct?
Finally, I'm looking at a charge controller. What I've read is they need to be the size of my solar array wattage divided by the voltage of my battery. So if my battery is 24V, and my Solar Array is 4800W (technically 5040), I do 4800/24 = 200a. The solar panels I'm looking at are 72 cell, so unless i'm mistaken I can go with a PWM charge controller to save a little bit of money? I've been looking around and I think a 200 amp PWM controller tends to go for around $1000?
Do these numbers sound correct? I'm looking at a rough cost, without wiring or mounts, of about $3000? Is there anything obvious I'm missing? Am I getting myself into trouble here or is this a good starting point for more research? Further, assuming in the future I wanted to add a second battery, what pitfalls should I avoid? And if I wanted to add more solar panels, that would mean I'd need a second inverter, correct? Would it be smarter to size my inverter upfront for any future expansion?
Thanks in advance for any response, I'm sorry if this was rambling. It's just simply soooo much to take in.
Long story short, I've calculated that, with the equipment I have to do my work, I need a budget of about 4800w per day to run my development computer and some other necessities. A friend of mine in the area converted his garage into a home office and runs it off of solar power (and he also warned me how deep of rabbit hole this can all be, haha), and he gets away with a 4800w system, so that's what I've targeted.
What I'd like is a system where I can use solar panels to charge batteries to provide this 4800w daily. Ideally, I'd like to start with something at 4800w initially, then grow it with redundant batteries for prolonged periods of rain, but for right now, I'm concentrating on having a single battery system. My friend recommended I look into server batteries as they can be had at good prices here in Texas because, while they're nearly impossible to ship cheaply, we aren't afraid of driving 200 miles in this state to pick up something. And, low behold, there's a place in Dallas selling server batteries that seem like they're what I need: https://signaturesolar.com/all-products/batteries/server-rack/eg4-lifepower4/
My plan is to get one of those 24V 200aH batteries, which would provide me a capacity of 4800w if I've done my calculations correctly. That would run me $1250.
My worst-case peak solar hours by month according to a calculator site are:
Jan: 4.08
Feb: 4.27
Mar: 4.89
Apr: 5.48
May: 5.7
Jun: 5.67
Jul: 5.63
Aug: 5.82
Sep: 5.6
Oct: 5.33
Nov: 4.57
Dec: 3.74
So I'm doing my calculations based on an average of 4 hours of peak sunlight per day (since I can skirt by with less power in the winter).
I've looking into buying used Solar Panels from this place in Dallas: https://beenebrothers.com/product/ja-solar-315w-solar-panel-used/
That's a 315w solar panel. As I understand it, that means the solar panel can produce 315w per hour at peak sunlight, so at 4 hours of peak sunlight per day worst-case scenario, a single panel is producing 1260w. So I'd need 4 of those panels to produce the 4800w I want my battery to hold in one day? Is that correct? 4 of those panels at $60 each would be $240.
Assuming I get the number of panels I need, I'm next looking at an inverter. I need it to be the size of my solar array, so the inverter would need to be 4800w as well, is that correct? I've been pricing them, and they look to run at about $500, does that sound correct?
Finally, I'm looking at a charge controller. What I've read is they need to be the size of my solar array wattage divided by the voltage of my battery. So if my battery is 24V, and my Solar Array is 4800W (technically 5040), I do 4800/24 = 200a. The solar panels I'm looking at are 72 cell, so unless i'm mistaken I can go with a PWM charge controller to save a little bit of money? I've been looking around and I think a 200 amp PWM controller tends to go for around $1000?
Do these numbers sound correct? I'm looking at a rough cost, without wiring or mounts, of about $3000? Is there anything obvious I'm missing? Am I getting myself into trouble here or is this a good starting point for more research? Further, assuming in the future I wanted to add a second battery, what pitfalls should I avoid? And if I wanted to add more solar panels, that would mean I'd need a second inverter, correct? Would it be smarter to size my inverter upfront for any future expansion?
Thanks in advance for any response, I'm sorry if this was rambling. It's just simply soooo much to take in.