Really Noob Question

KnowledgeSponge

Just getting into Solar. Doing a lot of reading but somehow interactive (posting on forums and getting live feedback) is more fun.

So, generally, I want to use solar power as a backup when the grid is down for short or extended periods.
I currently have a Honda eu2000i Generator in my "arsenal".

My "plan" at this point is about 1000 Watts of Solar Panel and about 500 - 700ah or battery pack capacity.

The main things I want to power are (in order of importance)....

1). Refrigerator
2). Lights
3). Computer and similar electronics
4). Other small appliances and electronics

My current arsenal of Solar Power ware includes...

1). Harbor Freight 45 Watt Solar kit
2). 1 x Q-Cell 100Watt Solar Panel
3). 2 x 80 ah AGM batteries
4). 1 x 200ah Marine Battery
5). 1 x cheep cheep 30A ebay PWM Solar Charge Controller

My next planned acquisition is a ProWatt SW 2000 Inverter, then, 1 additional 100W panel per month

What should I focus on / acquire first?

Any traps I should avoid?

Thx for the guidance.

Cariboocoot

Re: Really Noob Question

Add this to your arsenal before you add anything else: Kill-A-Watt meter.

Plug your refrigerator into it. Watch it blip 1000+ Watts on start up. See it consume 130 or so Watts while running. Thrill to the Watt hours rolling up to over 1kW hour per day.

Then do the same for everything else, and add up the numbers.

Then price out what it actually costs to supply that much power from solar. (You will suddenly find everything you've got in solar equipment now is useless.)

Then go give your generator a hug; it's your best friend in a power outage.

KnowledgeSponge

Re: Really Noob Question

Cariboocoot wrote: »

Add this to your arsenal before you add anything else: Kill-A-Watt meter.

Plug your refrigerator into it. Watch it blip 1000+ Watts on start up. See it consume 130 or so Watts while running. Thrill to the Watt hours rolling up to over 1kW hour per day.

Then do the same for everything else, and add up the numbers.

Then price out what it actually costs to supply that much power from solar. (You will suddenly find everything you've got in solar equipment now is useless.)

Then go give your generator a hug; it's your best friend in a power outage.

Cool answer :cool:
thx

RandomJoe

Re: Really Noob Question

You have almost exactly started down the road I did. I'm no expert, this is all just my experience and personal opinion/suggestions...

My motivation was sitting in the dark and cold for several days after an ice storm, never wanted to do that again. It was also just because I like tinkering with electronics and solar power, that helps to offset the fact there's NEVER going to be any payback in this...!

As Coot said, you MUST know your loads. For purely backup purposes like you describe, you also have to put some thought into how you're going to plug things in. If all you have is a one-room shack it's not so hard, if you're trying to power items in various rooms around the house things get more complicated.

In the end my system has grown to 2200W in panels on the roof, 880AH 48V battery bank (8 x T105 "golf cart" batteries), a full Outback Power system - FM80 charge controller, VFX-3648 (think that's it) inverter, FNDC battery monitor, Mate interface. I also have a manual transfer switch to switch inverter input between grid or generator (a separate circuit run to a bulkhead connector on the back patio so I can plug my EU2000i in without running a cord through a door or window), a breaker sub-panel to distribute the power, and have rewired some of the circuits in my house.

Let's not forget the INCREDIBLE PILE of miscellaneous supporting materials that are required to mount and connect all that stuff! Panel racks, screws / nuts / bolts, wire (of various types), conduit, enclosures, the list is quite extensive. (And expensive!)

I self-installed everything, so my only "costs" were materials - if you count my labor as "free". I'm somewhere around $10,000 total and even with just that number I'll never see this system pay back. I'd have to run the system for something like 54 YEARS - *without any failures* - just to break even. Grid power is cheap! Of course the battery bank will have to be replaced several times in that span, so forget payback.

On the other hand, with the setup I have now most of my house can switch to solar / backup power instantly if the grid drops, or on command via computer. I haven't had any major outages in that time, just one several-hour one, but quite a few shorter ones and I pretty much never know. Just notice the microwave clock (not on backup) has reset! I do get a small return on investment by utilizing the solar system as much as possible. I drop grid each morning, draw the battery bank down some, then let it replenish during the afternoon. Go back to grid at sundown.

Unfortunately I can't go 24x7 offgrid with this setup. I use too much power! My battery bank is good for about 2.5kWh to 75% SOC, the fridge takes 1.6kWh and my computer loads eat the rest up in a hurry. (I have some "servers" on 24x7 - nothing fancy - total wattage is only 150W but that's still 3.6kWh/day!) In an extended outage, the numbers aren't so bad - the servers would be shut down and I'm willing to take the battery bank to 50% SOC, I just don't want to do that every day.

Several problems with expansion: Cost, of course. I'm running out of room on the roof - plenty of space for panels, but the "prime" sunny space is taken. Anything else will be less-than-prime and be shaded sooner - vicious cycle, now I need even MORE panels for the same output totals! I could increase the battery bank, but then I'd really need to increase the number of panels to ensure proper charging current (with my usual loads applied).

Such a fun game!

Now, if you can get through all that and still want to do this...!

My primary suggestion would be to get good equipment! Yes, there are cheaper ways to put a system like this together but the beauty of a system like Outback or Xantrex is that everything communicates so it works well together and you have much better control over what's going on. I went with the Outback system over Xantrex because they published docs on the comm protocol with their Mate so I could integrate it into my home automation system. It was a tough decision, Xantrex has some really cool features in their firmware - I really wanted "load sharing", where it will add grid power to whatever the solar system can produce, you aren't limited to just either-or. Were I buying today, I think my preference would go to Midnite Solar, wish they had an inverter...!

Also, try to at least have a fair idea of your endgame. You can build a system in phases - I did, started with 500W in panels, then 1kW, then 2kW, also started with 6 batteries then added two more less than a year later (don't wait too long on batteries though, you don't want to mix old and new) - but be sure you can get from where you are now to where you want to be without too much "waste". In my case I started out with a 12V system but realized fairly quickly I wanted to go to 48V. Fortunately the charge controller I had bought (the FM80) works just fine on both voltages so could be reused. The 12V 1500W Samlex inverter of course couldn't be used.

Think about the battery bank some too. 12V is "easy" - so much stuff available at that voltage, although much of it is pretty cheap (and I don't mean cost). If you have a really good reason to use 12V, it may even be a good idea. I'm a ham radio operator, and thought at first to run my station directly from the bank. Problem is the wire sizes get HUGE! There's also precious little "wiggle room" at 12V - the difference between full charge and inverter drop-out voltage is quite small. 12V lights and appliances are also quite a bit pricier than the 120V equivalents. At 48V there's more wiggle room on voltage and the current draw is 1/4. Much smaller wire sizes required. I do still have a small 12V system for the ham bench, but everything else is on the 48V system.

gww1

Re: Really Noob Question

I really think random joe pointed out the need to have the proper motivation to want a solar system and that you can't beat the cost of using the grid. I also think you really need to look at how things affect each other in the system. Hard to change just one part. There is so much stuff that cost alot that you don't think of in a system. Racking, wiring, connectors, trenching, etc etc.... I am over $10,000 and have half of that, or more, still to go to see the potential of what I have. I keep getting the caculator out and try to figure pay out and I think with the batteries I will only be losing about $0.50 a kwh above what I would have to pay for grid power for the rest of my life. I don't want to quit though.
Cheers
gww

NorthGuy

Re: Really Noob Question

gww1 wrote: »

I keep getting the caculator out and try to figure pay out and I think with the batteries I will only be losing about $0.50 a kwh above what I would have to pay for grid power for the rest of my life.

$/kWh measurements are deceiving. After I installed the system, we undertook a conservation effort, which in fact increased our per kWh cost (because the cost is the same, but we use less kWh). If you look at something more suitable, such as yearly amortized cost, I'm well ahead of the grid. My initial investment will pay off in 9 years. And that is not counting potential increases in grid cost over these years. Although my grid was expensive.

So, it all depends ...

BB.

Re: Really Noob Question

gww1 wrote: »

... I don't want to quit though.
Cheers
gww

We are still talking about solar RE power... Right?

-Bill

KnowledgeSponge

Re: Really Noob Question

I got into Solar specifically to provide "enough" alternative renewable energy to power basic necessities such as a refrigerator for extended periods.
I guess I'm one of those that feels the grid "could" go down for more than a month or two. (It went down for 3 weeks during a hurricane a few years back)

So I'm not concerned so much with the financial aspect of it as I am the convenience it will provide in a disaster.

I've only spent about $1500 and have already reached my goal of being able to power the refrigerator during extended power outages.
I'll increase capacity to about twice what I have then just improve the setup. 600-1000watts is all I'm shooting for.
And only to power essentials. Not to replace the grid entirely.

Cared for properly, batteries can last many years. I have one that is 4 years old and still performs to 95% of the new ones.
(based on simple tests with current draw over time and battery testers)