• Have you tried out dark mode?! Scroll to the bottom of any page to find a sun or moon icon to turn dark mode on or off!

diy solar

diy solar

7 newbie questions

Ericccc

New Member
Joined
Dec 15, 2023
Messages
5
Location
North Carolina
Complete newbie here and hoping to find answers to what I assume are some very basic questions.

But for some very basic background there are two things I'm looking to do.

One is to get a small non-grid-tied solar system at my grid-tied house in order to experiment and learn, reduce my electric bill a little (even if those savings never add up to as much as I pay for the system), and maybe eventually enlarge that system to meet my most minimally critical electricity needs in the event of a grid power outage (at least during the day on sunny days.)

The other thing I'd like is to have a complete but minimal solar system at a cabin where I don't have grid power, but I have a wood cookstove I can use there, and I plan to use an outhouse, plan to do without running water... so I wouldn't ever expect to use much electricity there, but I'd like to have lights, run a freezer, maybe be able to use some power tools on sunny days...

So the questions:

1. I currently own practically zero tools for doing electrical work. What would a complete set of all the basic tools I'd need to set up and maintain my own solar electric systems cost?

2a. I'm not yet even seriously thinking about taking my house completely or even mostly off-grid, but very, very roughly what would it cost just for a quality system (not counting tools and if I could supply all the labor myself) to go completely off-grid in North Carolina if I were to continue using the roughly 1200 kWh/month that I currently use for my house and small farm? And what additional costs would I have over the life of the solar panels?
2b. Very, very roughly what would it cost for a complete system capable of supplying just 300 kWh/month (but with components compatible with future expansion up to 1200 kWh)?

3. What are the most common solutions for people that are completely off-grid and not-grid-tied to the constraints of winter and cloudy days? I assume practically every off-grid solar system is sized much, much larger than it needs to be to supply the electricity needed in the summer on sunny days in order to still have enough electricity for most of the winter and for cloudy days, and even then I assume most people that are completely off-grid still have generators or some other source of power besides solar for the longest periods. What's the typical range of how over-sized off-grid solar systems typically are under optimal conditions in order to still be usable most of the rest of the year? If you can't feed that surplus power back into the grid, are there other possibly transferable ideas for what to do with that surplus electricity besides just not using it?

4. If I only ever did laundry, irrigated the garden, and did other flexible electricity-consuming things when the sun was shining, and if I only cooked in more energy-efficient ways like with an instapot or used completely non-electric ways to cook when there wasn't plenty of sun, could I potentially save a significant percentage of what I'd otherwise need to spend for a solar system?

5. Do people have mixed AC and DC off-grid solar systems? For example, is there any reason not to use DC for lighting but have an inverter to be able to use AC for appliances that might not be available or that would be a lot more expensive in a DC version?

6. What's the best way to find out the limits of what I can legally do with solar panels without having to get permits, hire licensed contracts, or otherwise have to deal with any government offices? How much do those limits vary across the US and what's more or less average for what's legally allowed without regulation?

7. I like Will Prowse's teaching style a lot, so I plan to get his book, even though mobility isn't something I'd be looking for, but what other books would be good to read in order to gain an understanding of all the basics I should know before I even try to buy my first little starter experimental solar system?
 
Welcome. Some of your questions should be threads within themselves. Many answers are mostly opinions, so you may get many answers.

Cost of tools.....you need a multimeter and having one with an AC/DC amp clamp helps a lot. You can expect $40 to $90 for a meter that is functional. Some wire stripers and crimpers are needed as well. There are many types and lots of cost ranges but cheaper tools are okay if just for home use. If you are wiring panels, the crimpers for the PV connectors are very handy. Wiring batteries, big crimpers are needed but you can also order custom large cables with the lugs crimped on already. If you just connect one or two batteries, maybe ordering custom cables would be better but a cheap large crimper is less than $100.
 
Just some quick answers before delving into the weeds too much:

1: Probably a hundred bucks or so at Harbor Freight for a ratchet set, screwdrivers, meter, and basic electrical tools like strippers and crimpers.

2: Roughly $3k for a 3kw 120v AIO, 48v battery, used panels, and wire. Take a look at Will's solar dolly video.

Cost in the long term for panels is pretty much nothing as they're usually still running strong after 20 years. The up-front and mounting is the expensive part, but on CL and Marketspace the average is about $100 for a 250-ish watt panel. Online solar panels are only a good deal if you're buying 1 or 2 small 100w or a pallet of larger as shipping costs are murder.

3: You can oversize if budget and space allow, but figure on having a generator to recharge the batteries every so often in winter. Getting an inverter generator is a must as most AIO's and inverter/chargers are picky about their incoming power.

4: Yes, the more you can do without electricity the smaller your solar system needs to be.

5: Yup, suprisingly common, I do it myself at my camp. Some 12v lights and the diesel & propane heaters run 12v and the rest of the lights, the fridge, TV, Starlink, PS3, all run off the inverters 120v.

6: You'll have to contact your local AHJ to get the exact details but generally if you're not touching the grid or mounting to yoir roof the requirements are pretty low, especially in an off grid cabin. Your solar dolly is a "portable" system and there's nothing usually required for that. Some AHJ's will have rules about ground mount arrays depending in your area.

7: Will's book has a lot of good info even if it is a little out of date now. This forum has too much info to fit in one brain. 😉

Let me go grab my blurb and throw it in here, it'll help get you pointed in the right direction.
 
Blurb time!

Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. :) Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round :) ) and help figure out which parts and pieces you're going to want to get.

Well that's the thing about solar systems, there is no 1-Size-Fits-All answer. Your system will need to be designed to fit YOUR needs. When you design and built the system, it's not going to be the perfect system for me, or Will or 12vInstall or anyone else, but it Will be the right system for You and that's the goal.

As for where to get started, let me throw my standard blurb in here to help point you in the right direction. There's going to be a lot of math and research involved, but that's going to be a LOT cheaper than just buying parts off of someone's list and finding out that it doesn't do what you need.

Don't panic on the Power Audit, you'll actually be doing that a few times. When you do the first pass put in ALL the Things that you might want. AirCon? Sure. Jacuzzi? Why not. MargaritaMaster-9000? Go for it.

The second pass will be the "I Absolutely Need This To Survive" list that isn't going to have much on there.

The third pass will be the "This is what is realistic" audit that you'll use to design the rest of the system.

The Power Audit is going to tell you 3 primary things: 1: How big does your inverter need to be to power your loads? 2: How much battery bank do you need to last $N number of days with krappy weather? and 3: How much solar panel will I need to install to refill those batteries in a 4 hour day (the average usable sun hours rule-of-thumb).

Once you know what you Want and what you Need and what your budget can Afford there will be somewhere in that Venn diagram where those three things meet.

After that, THEN you can start looking at parts.

Yes, it's a long drawn out process, but it's worth it in the end. Not every house has the exact same floorplan, not every vehicle is the same make & model, and not every solar system is designed the same.

Another thing to consider when doing your power audit is HOW you use your power. As a great example, we had a new user on here a while back trying to figure out power for his tiny home. He ran through the power audit multiple times and kept coming up with needing a 10kw+ inverter for a tiny home.

I pointed out that if he promised NOT to make espresso in the blender while frothing it in the microwave while his hair dryer was going, he could easily get away with a 3kw unit.

So, HOW you use your power is also a significant part of designing a system. If there was one single design that worked for everyone, there would only be one system for sale.
 
Thank you both very much for those very helpful responses.

And I'll take your advice, DThames, and separate out some of the details on one or two of the questions to separate threads.

Thanks again!
 
I typed something else that I realized didn't make sense, and I can't figure out a way to delete it, so never mind this post.
 
4: Yes, the more you can do without electricity the smaller your solar system needs to be.

I didn't mean to particularly ask about doing without electricity but about postponing electricity use to optimal times. I think you answered a very similar question when you talked about not making espresso in the blender while frothing it in the microwave while his hair dryer was going... but I was wondering particularly about batteries. If I still used lots of electricity but postponed most of my electricity usage to sunny days (if I only irrigated during the day on sunny days, only ran the washing machine during the day on sunny days...) and only used very little electricity the rest of the time, am I correct to assume I could get by with a very minimal battery system but still be able to use lots of electricity while the sun was shining?
 
Hi - a question which I ought to know the answer to …. But don't. I have just replaced my inverter (lasted 14years). The new one reports 'pv fault' which from the error code was over-voltage (single string of 18 panels). I disconnected 6 panels and the inverter now works. My old inverter was a 'single' MPPT but the new one has two inputs. Here's the question - if I divide my 18 panels into 2 strings of 9 and connect each string to its own MPPT port, will the inverter see the voltage of each string or does it 'add the voltage of each string together'?
 
I didn't mean to particularly ask about doing without electricity but about postponing electricity use to optimal times. I think you answered a very similar question when you talked about not making espresso in the blender while frothing it in the microwave while his hair dryer was going... but I was wondering particularly about batteries. If I still used lots of electricity but postponed most of my electricity usage to sunny days (if I only irrigated during the day on sunny days, only ran the washing machine during the day on sunny days...) and only used very little electricity the rest of the time, am I correct to assume I could get by with a very minimal battery system but still be able to use lots of electricity while the sun was shining?
Answer....for example....I have about 4000watts of emergency solar panels and about 10kwh of batteries. I don't like to run down my batteries if not an emergency but on a sunny day, maybe use some of that solar. I can switch my "critical loads" panel over to the emergency inverter. If it is really nice and sunny, I can heat or cool my garage from that power. If it partly cloudy, I can run my critical loads only and the solar will keep the battery charged. If a cloud goes over, the power will come from the battery but then charge back up when the cloud passes. If I had a smaller battery, this would still work but it would just discharge the battery to a lower state under the same conditions.

Hope that is helpful
 
Regarding tools, I would suggest you also look at a non-contact voltage tester. I have a Klein. Your cabin sounds remote, and I’d personally plan on having someone check up on me periocally if working alone. I don’t know who has this avatar, but “remember kids, electricity can kill you.”
 
Regarding tools, I would suggest you also look at a non-contact voltage tester. I have a Klein. Your cabin sounds remote, and I’d personally plan on having someone check up on me periocally if working alone. I don’t know who has this avatar, but “remember kids, electricity can kill you.”
My brother brow beat me into getting starlink at my camp so he could check in on me. I made a forum thread instead.
 

diy solar

diy solar
Back
Top