With Instructables you can share what you make with the world, and tap into an ever-growing community of creative experts.
Tell us about yourself!
12V is OK for small installations like campers and RVs, but I wouldn't use it for a system like this because of the huge currents and massive wire needed. His inverter is 2500 watts, and with 12V, I think that would need 4/0 cable. He's going to have over 200A going into the inverter at times, which is dangerous in a DIY system in my opinion. He could have 1/4 of that with 48V. Grid tie can eliminate the whole bill, not just a little. Well, I need to qualify that; they do charge $10 a month for the privilege of using the grid, but I don't mind that too much because they are, in effect, providing me with a huge unlimited battery that I never need to maintain.
You said "the power company will let me tie into them", so it depends on the purpose of the solar. If it is to save money by lowering your bill, you want a grid tied system. You can do that if your power company allows it and allows for net metering. If you want to have backup power for when the grid goes down, the cheapest way is with a generator, but solar can be used if you don't mind paying 5-10 times the cost of grid power.
That junky install makes me glad I am not one of his neighbors. The fact that his system is 12V should tell you something. "So you think buying a generator that takes fuel and maint cost is a better solution than buying NiFi batteries once that don't take fuel, lol."Yes
I just read an article where he says ""...And I was having trouble because I wanted to vacuum but there were no sunny days. I can't run my vacuum if I want to have power in the evening."So he's having to carefully conserve so much that it has changed his lifestyle. Meanwhile, with my grid tie system, I'm able to run the A/C, hairdriers, TVs, anything I want, and still spend no money for power. Looking at his roof, my system is about 1/3 of his size, physically. There is one difference: If the power goes out, I have no power, but he does. To me, having all the power I want, when I need it, for free, I can suffer through an outage once or twice a year. So even if he didn't have any battery cost whatsoever, I would never advise anyone to do what he did, unless they are just really into it. For him, it's a hobby, a labor of love, and all that. That's great for him, but it's not what most people are in this for, they just want to save money or get off the grid without understanding the ramifications. Even if there WAS a ROI, you'd have to value your time at zero to realize that.
People (like me) go with grid tie because net metering makes it economically a win (unless you end up in a bad lease, PPA or simply over-pay). I installed my 4 kW system myself for $8000, the IRS gave me back 30% of that and my $1200 annual power bills are now slightly negative :-) I've paid no power bill for two years now, and it's a pretty good feeling, and slightly weird to have the power company owe me money. If I had batteries it would be very different. With FLA or AGM batteries cycle cost at roughly $.50 to $.80 per kWh, my power cost would more than quadruple. SO there is no way I would have a battery system. If I needed backup power, I would just buy a generator. At work we install large off-grid solar battery systems, but not with NiFe because the ones we looked at had high internal resistance and low charging efficiency, which would require much larger arrays. The people we have talked to that do use them say they are a PITA to maintain and take a lot of water, and that they wouldn't buy them again. At least they don't suffer from sulfation. I think they are worth watching to see if they improve, but I wouldn't suggest using them now unless you like to fiddle with batteries.If you have a system of your own and would like to post your experiences with it, by all means do so, I've love to hear about it. I value advice based on first hand experience much more than advice based on what someone reads on the internet.
Amy, your contributions on solarpaneltalk are great! And I think your youtube videos are great too.
It's because off-grid solar power costs from 5-10 times what it does from the power company per kWh. There is never a ROI due to battery cost (initial and replacement cost). With grid-tie, you can have an ROI.
Join 2 million + to receive instant DIY inspiration in your inbox.
Download our apps!
© 2016 Autodesk, Inc.