For the past 6 months or so I've been running a little solar off-grid power solution at our firework storage container.

It is made up of basically 2 50w solar panels, a Morningstar MPPT charge controller and a Elecsol 100aH battery. It's current purpose is to power a little alarm panel, but I have bigger plans for the system once it is proven a workable solution.

To monitor it, and to also test how well it will stand up to running a CCTV system 24/7 I've also been running a Mikrotik router, with a 3G card running a VPN back home so I can remotely monitor the Morningstar controller.

During the summer the experiment went well, but as the days are getting shorter I am starting to get battery low warnings from the alarm panel. Shutting off the Mikrotik router is currently solving this problem, but I had hoped that I could run at least the router, monitoring hardware and at least once CCTV camera. Clearly I am lacking in capacity and diversity in the system.

Unfortunately due to a quite frankly terrible bit of monitoring hardware from a company called PacketFlux and my inability to get it working with Cacti as it should, I don't have any useful data to play with. Shame as that was the whole point!

I was just wondering if anyone has any experience in this type of installation, I am looking to avoid big pitfalls as I am already spending too much on this already.

I think I have already decided to add another battery and change the solar controller to something with built in monitoring (or at least one that can send direct via GPRS). But I was also thinking about adding wind power to the mix, anyone have suggestions ???

Edit - I should also add I plan to run some 12v LED lights from the system as being there in the dead of night with no lighting is just plain scary !!!

Cheers

Cris

Very interesting experiment. I've been looking into this too because at a certain point I would like to install solar panels onto the roof of my house. But, contrary to almost all current consumer installations, I do not want to also connect this system to the main grid.

Here in Belgium solar panels were big business, because of all the government grants. A lot a people jumped into this because the were convinced the panels would make them a lot of money. Basically the government would refund you an amount of your installation costs, and also pay you for every 1000 kW you put onto the grid. This seemed like a good deal, but I've never believed in it because I just don't trust the government. I've always said that, once hundreds of thousands of homes have solar panel installations, the government would start taxing them. Turned out I was right, because a couple of months ago they announced such a tax. And I'm pretty sure that tax is only the beginning.

For this reason I do not want to connect my solar panels to the grid. So I've been reading up on the matter. There's a lot of good info on the web, like eg. which battery type to choose etc.

So I never got passed the theory stage (yet), but I also feel there's still a lot to learn before I can install the perfect setup for my use.

With regards to wind power, I've also looked into that. But unfortunately I've come to the conclusion that it's almost never worth it. I don't know how the situation is in the UK, but in Belgium, consumers cannot install turbine master that are higher than 12 meters. I can see why they decided on this number, because higher than that would quickly become very annoying for the neighbours in densely populated areas. Unfortunately, the constant wind speeds you need for a turbine to run reliably are much, much higher than that. In the first 12 meters, the wind is scattered and not constant. There's also a very good chance it will get blocked by surrounding buildings, trees, etc...
So that's one point: wind turbines work best if you live in a rural environment, because you need an open area. Also, for the whole investment to be worth it (read: producing more than break even during the lifetime of the installation, considering the cost) you need a more or less constant wind speed of AT LEAST 4 to 5 m/s (= 8 to 11 mph). This is almost never do-able with consumer turbines, unless you live in rural areas and preferably along the coastline where there's traditionally always more wind.

I've only encountered ONE wind turbine which, due to it's revolutionary design, does not experience most of these drawbacks, and that's the Hybrid turbine by Alex Erauw. What this turbine is capable of doing is unbelievable. For one, it has a Betz rentability of 56%! (the theorectical maximum being 59.3% - Betz Law). Almost all other consumer wind turbines don't even reach a Betz value of 10 to 20%. Read the naked truth about wind turbines here (crappy website, but the info is genuine), or view a video here. The biggest downside of these turbines is they are ugly to look at and they still don't perform miracles, you still need a basic amount of constant wind (4.5 m/s), or it's just not worth it.
A few other videos here, here and here
This is the commercial site of these wind turbines : Dyna.

All in all, Wind power turbines are a lot harder to implement (correctly) than solar panels. It may be worth it, but it depends on a large number of factors. This makes it a big hassle and almost never worth it for consumers (compared to solar), unless you're one of those people who doesn't mind a challenge.

How far is it from your home, and what size battery do you use? We use a small leisure battery and solar panel to power the electric fence round our cherries, it didn't keep pace with demand this year so we bought another battery and swapped over every few days to allow mains charging at home.

I certainly don't mind a challenge, and our location would be perfect for wind. But I don't own the site and only rent the ground the container sits on, so anything would have to be roof mounted and as you point out it gets very expensive and not really worth the money, I think!

The container is in the middle of a field, up against some old barns. We positioned it with Solar in mind so it is generally south facing with nothing shadowing the panels. I had thought 100w would be enough, but I am starting to think I need something like 200w.

The nearest connection point to the grid is about 400m away, and due to the nature of storing explosives it really needs to be low voltage anyway

Cheers

Cris

Would they not tax the panels whether or not they were attached to the grid?

tanstaafl.

They don't actually tax the panels (yet), but they tax the amount of power you put back onto the grid, saying this is a fee because you're using the grid. Which is BS of course, since that was part of the deal for almost every solar panel owner from the very beginning.

Besides, I'm thinking : if you don't apply for a government grant, they have no way of knowing you have those panels. Which is the way I like it. I don't see them sending out public servants to go and check if your roof actually holds any PV panels or not.

Doing some straight (theoretical) maths on your setup. Assuming 12V battery you have 1200Wh using the full rated capacity of the 100Ah battery.

2x50W will take 12 hours to fully charge that at full power. You'll never get 12 hours of full power to charge in a day I don't think.

Another battery isn't going to help you if you can't charge it. An extra battery would only help if you had excess charging capacity that the single battery couldn't use. An extra panel if anything would be what I'd be looking at.

Do you have an idea how much power you need? Your load should be fairly constant as it is now. From there work backwards as to how much energy/capacity you need. 1200Wh is a fair bit of energy. That should run a 50W load for 24 hours if fully charged. If the number of sun hours per day x 100W is less than your average power x 24 you'll go backwards slowly. So you're probably slowly going backwards with the shorter days.

It is a 12v setup yes. I have been running at about 7w (I think) but was hoping to add some more if I could. The camera I am testing at the moment runs at about 2w in the real life test I have been doing, it's one of these...

http://www.ubnt.com/airvision#aircamdome

My idea was to design a system that could cope with almost no charge for 7 days, so during really bad weather we would more than likely be ok. What I am finding is that the battery appears to fully charge from the over night charge in 2-3 hours of morning light and the rest of the day is wasted basically. But these figures are changing as the nights get longer of course.

I think another 100aH battery and a 3rd 50w panel would be a pretty sound investment.

I may also look into changing the charge controller to something like this...

http://www.ecs-online.org/en/reload.html?green_controller.htm

They quote a figure of 2w of consumption for itself, and it is GPRS enabled already, so in theory I could save about 5w of power as I could turn off the SiteController (as it would be redundant) and only switch the MikroTik on when needed (for remote monitoring of the CCTV for example).

It's really hard to get good figures out of the setup I have at the moment, so something major needs to change!!!

I really like the sound of using wind, but I just can't seem to find anything that actually works!

Cheers

Cris

If you're really running somewhere in the sub 10W range, you should be able to go approximately 5 days on a full charge theoretically. In Australia, I'd be fairly comfortable with that - even overcast days you'd probably get there. UK is a bit different of course

2-3 hours sounds about right based on those numbers (i.e. 240Wh).

In that case the extra battery may be OK since you do have that excess charging capacity. As long as typically the energy produced each day from your panels is greater than the amount you use you'll be OK.

How would you switch on the router? Can that controller turn on loads via its GPRS module? But can it then operate as a router? In that case wouldn't it make the router unnecessary? Or you'd need two SIMs/connections (1 x GPRS and 1 x 3G)?

The alarm panel has it's own SIM card and you can control a relay via SMS, I use this to switch a 12v line on or off as needed. It's been on most of the time, but when it sent me a battery low warning (that means the 100aH battery has been disconnected by the charge controller) a simple text message turns off the Mikrotik Router and SiteMonitor, so when the sun comes back up as much power as possible is put into the battery.

I did get about 5-6 days of dull weather, but the days are getting shorter and shorter. It's really hard to tell as the system actually stopped logging data for 2 weeks before it cut off and I didn't notice!

The controller is pretty limited, it can't act as a gateway/router. It only sends packets of data back to a server for collating into a very nice but basic site. At the moment you can't control the relays remotely, only via pre-set parameters set up locally. They say they are working on a solution.

In an ideal world I'd like a one box solution, that uses almost no power. But where would be the fun in that!

I think I might try the extra battery and see how I go on. I actually need to move the battery outside the container anyway, so now would be a good time to do that. Hydrogen gas and fireworks don't mix! Who would have thought!

Cheers

Cris

Only batteries of the flooded type release a gas when charged. You could use Gel or Absorbed Glass Mat (AGM) batteries instead. Performance is superior, they keep their voltage better, self-discharge slower and they are completely leak proof. Of course, they are more expensive too.

I did look at AGM, but they are too expensive. Almost twice the price.

I know looking for MPPT in a charge controller is a good thing, but as for brand it's an area I don't know much about. I have a MorningStar at the moment, and as with most of these controllers getting data out of it isn't very easy!

Cheers

Cris

You need to be dedicated and disciplined about maintaining your battery bank. You can lose a ton of capacity for storing power if your batteries aren't healthy.

This is more than just checking the water level (although that is vital), it's learning to test the specific gravity of each cell and the voltage of each cell to test for sulfation. It's learning how and when to do equalization charges, etc...

Archeon: unless you want to invest the time to do this, it'd be better to just go grid-tied. There are a lot of other advantages to being grid-tied also, like having enough power to cover spikes in your normal usage or to compensate for inadequate charging due to several cloudy days in a row. At the very least, I'd put in a switch to be able to revert to the grid if your batteries are depleted (some controllers can do this automatically.)

Thanks John, any more tips on battery maintenance then ???

I've gone with these batteries after a bit of research...

http://www.elecsolbatteries.com/products/Leisure-Batteries/Elecsol-100.html

As the site is unmanned most of the time there isn't anyone there to check on a daily basis and I visit every couple of months (on average), so how regular do I need to be checking things ???

Cheers

Cris

Agreed!
I didn't specifically mention this, but that was the general idea I had in mind: be self-sustained as much as possible, but still have the main grid as a backup solution. I indeed plan to do this with a capable controller.
I still don't plan to let the government know though.

I would say that once every couple months is not often enough. They shouldn't get too low in that amount of time, but the consequences IF they did could be that you permanently diminished the capacity of your batteries. I'd plan on checking the water level in the batteries once a month. You should be fine with doing the rest of the stuff ( including the equalization charge ) quarterly or every 4 months. Because I didn't feel like typing so much, here's a couple of the google results for maintaining batteries that pretty much match my experience.

Maintaining batteries
Equalization charge

Our bank has 16 batteries, so it is a significant time investment. With only one or two batteries, it shouldn't take too long.