Desperately seeking info and understanding

[Amy Lucier]

Hello,

I am definitely out of my comfort zone here, as my knowledge of matters relating to "the Green Life" is virtually non-existent. Without a doubt I will be the the least-informed person who has ever interacted here; my questions will be rudimentary and exceedingly basic in nature. But all I need is one very patient person to have mercy and educate me about a few specific things. (I just wanted to get that out of the way...)

I need to understand various aspects of the functioning and economics of rooftop solar panels, having had them installed on my house in 2015. I know what some might be thinking: if you know nothing about renewable energy, why would you invest in solar panels? I guess I knew enough to convince myself it was a good idea.

In short, I liked the idea of "going green", ie. harvesting earth's natural energy to power my house. But what may have been the stronger impetus was my increasingly higher and more ridiculously exorbitant power bills, and my desire to escape the financial clutches of the local energy monopoly.

So, driven more by impulse and resentment than a profound understanding of the mechanics and marketing of solar, I dove in, full speed ahead. Questions would be later: 3.5 years later to be exact. My suspicions that something major isn't adding up on my power bill finally compelled my quest for a clue, and here I am.

That was more of a full post than introduction. Thank you.

Amy Lucier

[Dave Schwartz]

Welcome Amy,

I may not have more knowledge than someone like Rob but I do have a fair bit of time in the seat... rooftop system running flawlessly since August 2010 and reached simple payback at the end of October 2015.

[Joe Blake]

Hi Amy,

I'm sure there'll a few people here who'll be able to answer some of your questions or maybe even inspire you to do something you hadn't thought of previously. From my point of view, over the years I've learned that the "green life" is not (just) about hugging trees, saving small furry mammals or using renewable energy. It's about how you look at the world and seeing opportunities that other people may not spot, or even think of looking for. Some areas I've investigated include (obviously) renewable energy, both generation AND storage, transportation (bicycle, electric vehicles, rebound boots for walking), greening your house (lighting, rainwater harvesting, insulation), growing your own food (I'm currently in a glut of strawberries and my cherry tomatoes are approaching ripeness), clothing (I've got a 50 year old knitting machine and a 70 year old sewing machine, and a leatherworking kit), the list could go on. Like Dave Schwartz, I've been on this board for many years and am quite happy to share knowledge and experience. So I'd suggest you spend a bit of time wandering through the many posts here and "follow your nose" on any interesting topic that you come across. :idea:

[Amy Lucier]

Hi Joe,
Thanks for your thoughtful reply. I agree, and it's not really up for debate, that "living green" has implications and scope far beyond what some people think of when catchphrases like "renewable energy" and "environmentalism" are tossed around. It's an entire world view and way of life; one that will continue to expand and evolve over time as our understanding and consciousness grows, and as technology and innovations show us more efficient ways to proceed. I won't bring politics into this, but until we can, as a human race, make a serious commitment to the preservation of what resources we have left, the movement towards sustainability and renewability will be limited to the enlightened minority. As long as there are still entire counter-movements which literally refuse scientific realities like climate change, the cynic in me wonders if the efforts of green-minded folks will be futile ultimately. But I know better than that. We can't give up, or get complacent.

This is the second reply that I have composed because my first one was too long and preachy and circuitous. Where the written word is concerned I can ramble indefinitely and I am forever repressing this urge! (I really need to start a blog already)

Thanks again for your reply. I'm going to post my specific solar ?s and issues in a different forum and try to keep it concise...

[Bill von]

I need to understand various aspects of the functioning and economics of rooftop solar panels, having had them installed on my house in 2015.
OK. Anything specific?

In general there are two kinds of systems - on grid and off grid.

On grid systems connect many panels in series. Since panels run around 30-60 volts, that means you get panel 'strings' that are around 400-500 volts DC. DC isn't usable by most appliances, so a grid tie inverter converts that 500 volts DC to 240 volts AC, which then feeds your house. If you use more than the inverter can provide your loads draw from the grid; if you use less, the inverter feeds back to the grid. Most installations use something called "net metering" which means that if you generate 200kwhr a month and use 600kwhr, you only pay for 400kwhr. If you go "over" and generate more than you use, you generally don't get that money back, although you often get a small credit. If there is a blackout generally there is no backup power available, since the inverter needs to "see" a working grid to function. (There are a few exceptions to this.)

Off grid systems use a few panels in series to get a lower DC voltage. A charge controller then charges batteries. Small systems use 12V batteries. Larger systems use 48V batteries. An inverter then converts that DC voltage to 120-240 volts AC for the home to use. There is almost always a generator in addition, so during long stretches of cloudy weather there is a backup source of power.

There are also hybrid systems that do both.

In terms of economics, many utilities bill on a tiered system - so your first 600kwhr a month are one price (say 12 cents/kwhr) and your next 600kwhr are much more (say 18 cents/kwhr.) Thus getting a solar system just big enough to reduce your total usage so you are only billed in the first tier is the smart move. You can get a system large enough to "zero out" your bill but that usually isn't economical unless you live in Hawaii or California (high power costs.)

However, it should also be mentioned that reducing loads/improving efficiency is ALWAYS cheaper than solar. If your fridge is more than 5 years old, replace it. Get your A/C serviced and clean the filters regularly. Unplug "wall warts" that provide power to things like phones and speakers, and put them on a power strip so you can turn them off when you are not using them. Replace all incandescents with LED bulbs. Do that first, and often the need for solar will go away.