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Comment by jphil529 | Hacker News Reader

Really curious about the difficulty of doing a self install with Solar. I'm moderately handy (built a Sauna from no plans) and confident with electrical. Any gotchas?

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I just did an install to add solar and batteries to my shed to power lights and an AC. It was pretty easy. Hardest part was flattening the ground since I did a ground mount system. 5kw panels and 5kwh of batteries. $1000 for the panels, and $1,400 for the battery and inverter. $250 for the ground mount. Plus a bunch of miscellaneous expenses (tools, wires, permits, etc). It would be cheaper if I did it again since batteries and inverters seem to get cheaper every 6 months.

Check out https://m.youtube.com/c/WillProwse and https://diysolarforum.com/

I'm just getting into Solar myself and while it seems like a lot there are some things that you have to do math for. If you've got 10 panels you'll want to find out how to get all that energy to the inverter/mppt without going over the volt/amp limit on the device. This is probably the most difficult part and for everything else there's a huge solar community of people starting exactly where you are. I myself just bought an Anker solar battery and 2 panels that I bring out during the day to charge the battery and it runs my laptop and monitor for the evening after I get home from work. I want to do more but I'm renting so I'm just trying to find ways to do so. When my state legalizes balcony solar you bet I'm going to play with that too.

> without going over the volt/amp limit on the device.

It’s not clear what device you’re referring to in this context.

The MPPT solar controller.

MidNite has a sizing tool for this: https://www.midnitesolar.com/sizingTool/

So the most difficult part is using a calculator to determine the charge controller capacity.

No, you also need to calculate the voltage drop over your distance to show to minimum wire sizing, and the voltage and power levels at the ASHRAE minimum temperature, the current level at 156.25% over the wiring at the ASHRAE max temperature to compute the temperature adjusted resistance and show that your wiring meets minimum spec, etc.

It’s not too hard to actually do the computations. But there is a ton to learn. I installed my own 14.85 kW system last year, with batteries, and I spent hundreds of hours just researching everything. I know I went overkill, but the hardest part of the project was just getting up to speed on all the requirements to meet code.

Someday I’ll write up my entire experience and share my site plan I used for permitting in the hopes it will help someone else. But doing solar right is a nontrivial investment for a newbie (like me).

So the most difficult part is using domain specific online calculators to determine the wiring requirements and charge controller capacity.

The most difficult part is acquiring the necessary domain specific knowledge, including what your AHJ changed from the national codes. But yes, once you know everything it’s all pretty straightforward stuff.

No, just figure out how much solar you want and buy and accordingly sized charge controller/MPPT.

They will all tell you maximum input volts and amperage. You can calculate watts by multiplying those two and just need to wire your panels in a way that doesn't exceed either value.

Its not difficult, you just have to change the configuration of your panels between in series and parallel.

Ideally you dont buy the all in one batteries as they usually have anemic solar inputs.

It's fairly easy and there are a lot of forums around with knowledgeable people.

My main issue was ensuring wire gauges were correct. One's intuition about dealing with house wiring @15A changes when you're dealing with 50A circuits. Also you need to pay attention to things like equal cable lengths between battery banks so you don't overcharge one battery in a series.

However, I'm dealing with an off-grid cabin so I don't need to deal with any grid-tie circuitry, which would make it much more difficult and I'd definitely get an electrician for that.

Very cool. Thanks for the tips!

Modern off-road/off-grid inverter chargers make wiring to the network pretty easy. I'd still recommend an electrician, but most they'd likely need to do is wire the grid into the inverter-charger input, and your cabin to the output, and check whatever protection (like RCDs) your cabin has is sufficient/up-to-date.

I don't have solar myself but I worked for a solar tech company for a couple of years

I think the biggest gotcha we dealt with was that you can't (or shouldn't) just wire solar into your house and call it a day. You have to let your electrical company know, there are permits and inspections that need to be done before you wire your solar into the public grid. There may also be some relevant bylaws you should know about, or if you live in an HOA you should check their policy first so you don't start a fight.

It's like a lot of things. Conceptually easy, but bureaucracy makes it complicated

Alternatively, in Australia at least, "bureaucracy" streamlines the issues and at various times and locations offers rebates and schemes to reduce significant upfront costs and fold those into payments over time included in bills.

Globally, this of course varies.

I 100% agree with having inspections if you're grid tied. You don't want your system energizing the neighbourhood when the power goes out!

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