thebaldgeek

This may either change things or shut me down. Not sure just yet which….

http://www.batterystuff.com/kb/tools/calculator-sizing-a-battery-to-a-load.html

Long story short, we ran the numbers.
400 watts at 12v DC is 33 amps. To run 33 amps for 10 hours requires a 700 amp hour battery.
Yeah.
That’s a big battery. A. Very. Big. Battery.
Honestly. It’s too big.
Not only can I not afford something that size, but I also do not have the space to house it.

So. Options.
Clearly I have to pull back a bit on my desire to run the computers all night on the battery.
If we kick it back to 5 hours, things become more sensible.
If we move to a 24 volt system, things become more sensible.

Just to complicate things, our power company has voted to go from the current 4 tier power use system to a 2 tier. I am not sure what that is going to mean for our power bill. I suspect it will go up, but it also means I have to make the solar work harder to save more money for it to become profitable (or worthwhile).
Just to make things even more complicated, there is talk of them moving to a time of use system as well, but no solid data on when that may happen.

Ugh. It’s not supposed to be this hard!!

This is one of the most interesting things I have found and done in a technical aspect for some time……. (And yes, after you read it, you too will come to the conclusion that, A. I don’t get out much and B. I should get out more).

We had a customer ask us to help get some Opto set up to measure the mains frequency, why does not matter.
I thought it would be easy, turns out it only sorta is.
Long story short, there is a lot of noise from computers and stuff on the mains and that makes measuring it tricky.
Longer story short, use a 100 Hz filter and you are pretty much good to go with an Opto frequency module.

Here is the really fun part…. In order to double check that the filter was working, I put an Opto module at my house (with a filter) and another on my desk here at work (with a less than optimal filter).
I then networked the two Opto modules into my computer and used groov to plot the mains frequency measured from around 6 miles apart (that’s around nine and a half clicks).
Not sure what I was expecting, but I giggled like a kid when I saw it….

So, there you have it, my house and work have the same mains frequency.
That is soooooo cool!!!!! I mean just stop and think about what’s going on here.
We are measuring the frequency across town and they are just about are in lock step!
We can do this because I have set up a VPN (Virtual Private Network) to my home, so my work computer thinks it’s on the same network as my house where the rack of Opto gear is with the measurement module is on it.
The work computer is also on the work network, where my rack of Opto gear has the other measurement module on it.
groov is running on my work PC, and simply logs the data from each module.
They both have noise filters on them (the red one, the one at my house is the better filter – don’t ask) and so they track really well.

For another blog is how much the frequency changes and why.

Too Cool!!!!

I was going to email a few of my readers and go over this topic, but have decided to just throw it out there and you never know what may come…..

I bought 3 broken solar panels a few weeks back and am in the middle of repairing them and will put them up at my house.
Ok, thats pretty straight forward, so whats so confusing about that?

Whats the best way (ie, the cheapest) to use the power they generate?

If you are interested in the panels and the repair process, have a quick read of the blog I did on them over on the Opto website… I will wait here while you go do that……

http://blog.opto22.com/optoblog/repairing-broken-solar-panels

Ok, so thats the panels and I plan to epoxy / repair the next two this weekend. They should be on the roof a few weeks after that.
Thats all well and good, but then what?

They are 30 volt panels. I sorta planned to wire all three in series and get 90 volts, this way if one or more is a little shaded, I will still get some power from them.
I also planned to run a 12 volt battery and inverter, this way I could use the power from the panels during a blackout.
I chose 12 volt as I can easily get stuff to run off 12v and any parts I buy could be used in a car or RV down the track if (when) we move out of the house.
So whats the problem?

90 volt to 12 volt chargers are expensive.
Here is the ‘best’ one that I might be able to afford…..
http://www.amazon.com/Solar-Charge-Controller-150VDC-Display/dp/B00K71C7PI
The thing is, when you do the numbers, I will have 60 amps, and this thing is limited to 50, so I am throwing away 10 amps, but only if the sun is shining and the batteries are flat, so I am not sure how often that is going to happen.

Should (can?) I run a 24 volt system and forget this charger all together and just run the solar panels into the battery with a simple on/off switch?
If I do this, then I save 250 bucks but at the loss of the usefulness of having a 12 volt system…. What is that going to cost me in the long run?

Should I forget the idea of putting the panels in series, and just get a 30v to 12 volt solar charger for each panel? (I have not looked, but suspect that I could buy 3 of these for less than the cost of the one big charger).

The other issue I have is working out the size of the 12 volt battery…. I have a 400 watt load I want to run as long as I can after the sun goes down.
So how many amp hour battery do I need to run 400 watts for 10 to 12 hours and only have around a 20 to 30 percent depth of discharge of the battery?
I was thinking of going for a 12 volt deep cycle battery, either gell or lead acid. Lithium batteries are around, but they are still really expensive. (I was quoted 1000 bucks for 200 amp hour for a used pack).

My house runs around 800 watts all the time, of that 400 watts is my computer gear. As it happens ALL the computer gear is plugged into my UPS, so the plan is to have the solar system run an inverter that will be switched in and out of the UPS, thus running all my hobbie stuff off solar / battery when it can. When I can’t, the UPS just gets switched back to mains and the batteries can recharge off the solar.

So, thats where I am at. I have 750 watts of solar. I have 400 watts of load that is wired back to one outlet via a UPS. Seems prime to switch the UPS between mains and solar and try and run the UPS for as long as I can after the sun goes down.

How do I do that as cheap as possible?

Windows PC’s are getting smaller and cheaper.

http://www.engadget.com/2015/06/23/lenovo-ideacentre-stick-300/

Lenovo is joining the fray with the Ideacentre 300 Stick. The extra-tiny Windows PC is much like a sleeker, more polished version of Intel’s Compute Stick. It shares the same 1.3GHz Atom chip, 2GB of RAM and 32GB of built-in storage

Apparently it will sell for 130 bucks here in the States.
Im sure it will be running Windows 10…. Have not looked at it yet, so cant comment on that aspect…. But, by all accounts it should go pretty good for most light duty computing.

Pretty crazy when you can just plug it into the back of a tv and get going (using 2 or so USB ports for power).

I have no idea what I would use one for, but hey…..