Solar for Renters (Part 2)

When I left off, I was describing the first part of my solar power system designed for renters. You can read about it here.

As I described, I placed 250 watts of Renogy panels on my roof. Given how much power they output, the panels are pretty reasonable in size. All the panels together are about 6 feet by 4 feet. You could definitely fit this on the balcony of a city apartment, and could probably even go bigger, using Renogy’s 170 or even 300 watt panels. I connected the panels to a railing using metal safety chains used for theater lighting, which work great.

A quick note here; shading makes a huge difference in panel output. With even a tiny bit of shade–like from the railing of a balcony–my panel’s output was HALVED. That’s a huge loss, and I ended up moving my panels to a different part of the house with full sun to avoid the issue. If you’re designing system for a small balcony, make sure to avoid panel shading as much as you can.

From the branch connectors, I used a 40ft 10awg cable from Renogy to get power down from the roof to my garage. That length and gauge is not ideal for a 12v system; really it should be 20ft max, and I’m probably losing about 10% power with the long cable. But it was a long run down, so again, oh well. If you’re able to put your battery right by your panels, you could avoid this and get a big efficiency boost.

In the garage, the cables go into a 30amp Renogy Adventurer charge controller. I bought an extra Bluetooth module, which allows you to monitor the system in real time from Renogy’s app. The Adventurer plugs into a 12v lead acid battery, with about 120 amp hours. Sealed lead acid or even lithium would be better, but this works fine for initial testing.

From there, I use a 500w Renogy inverter (the lowest wattage available today is a 700 watt unit) to turn the panels’ output into 120v house current. Renogy’s inverters are really good, and have safety settings like low voltage protection and overcurrent protection. They’re also able to adjust their fan speed and other settings up and down based on load, so you can leave them on all the time and they don’t draw that much current at idle. You even get a little car key style remote to turn the inverter on and off remotely.

Here’s how the whole thing looks in action:

So how does it actually perform? Stay tuned for Part 3 to learn more!

Solar for Renters (Part 1)

A few years ago, I wrote an article about my dream of building an apartment-scale solar power system for renters. I wanted the system to be something you could install on a balcony or in a backyard, that could generate power off-grid without having to install traditional solar panels on your roof. My vision was for something renters could use, in anything from a small city apartment all the way up to a rented suburban home.

Well, several things have changed since I wrote that article. For one, solar panels have gotten a whole lot cheaper and better. You can now get off-grid panels for well under $1 per watt, and batteries and charge controllers have both come down in price. There’s exciting new battery options, too, like lithium batteries which might destroy your bank account but eliminate the need for ongoing maintenance and have a much lower risk of catching fire/exploding than old fashioned lead acid.

So with all these things coming together, I finally went ahead and built my system! This article covers the basics, and I’ll go into a lot more detail on specifics, too.

First a word of caution; if you have any doubt about working with electricity, hire a professional. And although this system is designed for renters, make sure your landlord allows this kind of thing before installing! 

Okay, with that out of the way, here’s what my system looks like. Ideally, I wanted to have at least 200 watts of generation capacity, as I wanted to run a computer off solar power. So the first part of my system is 250 watts of panels from Renogy; three 50w panels and a 100w panel. Ideally all your panels would be the same wattage, but I had the 100 watt panel already, so oh well. These are wired up in parallel using a four port MC4 branch connector, and placed on a balcony on my home’s roof.

This is part one of a series of posts about the system—please follow my blog for the next post in the series!