Category Archives: DIY

Micro PV

So, having moved the garden shed and the PV panels in August/September 2011 to a more sun friendly position, I was pretty sure that there would be more output from the system over the next 12 months. Now, that 12 month interval is just coming to an end.

When I checked this evening, the average power generated 24×7 for the last 12 months as per rrdtool is 40 Watts, with a peak of 357 Watts. Which equates to approximately 350kWh, or somewhere between 70 and 90 Euro worth of Electricity for the year.

So in short, yes there was an increase in output, an approximate 42% increase in average power and a 100% increase in peak power. At least now I can tell myself it was worth the effort!

Radio-Active weekend

In between cleaning the rubbish off the deck, entertaining my cousin Saturday afternoon, getting the tables and chairs out, putting the glass back into the glasshouse (literally), and getting the lawn cut. I got some time to look at some digital modes for Amateur Radio.

First up was getting my tunnel set back up to AMPRNet. That took a bit longer than expected, but I finally got it all sorted and have rip44d (Written by Heikki, OH7LZB) running, with a slight modification to use a separate routing table for the “44” Network. More on this below.

Next up, was to get my 4m (70Mhz) AX.25 port back running. Then configure LinuxRMS to allow the port to be used as a Winlink Gateway.  This will allow anyone that can connect to my 4m port to use it for sending and receiving email over radio (just like a smart-phone, only much more slowly 😉 and much larger range between base-stations).

Now, the only real way to test it properly was to connect to it from another machine which meant configuring paclink-unix on my (recently re-installed) Linux laptop.  So I unpacked my Emergency Communications Go-Kit, plugged it all in, downloaded and installed the latest version of paclink-unix. Configured it up and tried to connect.  Lo and behold it all worked.

While I was as it, I tried out the wl2kax25d daemon and the peer-to-peer mode of paclink-unix and it also seemed to work quite well (for instances when no Winlink gateway is available).

Now that I had the tunnel to AMPRNet running, I though I’d test it out some more so configured up a second ethernet port on the machine with my AMPRNet address of, and configured the (same) laptop with the address of  Once it was all set up I tested the wl2ktelnet daemon which is the paclink-unix mechanism for directly connecting to the Winlink servers when Internet connectivity exists. Much to my surprise (that I hadn’t stuffed something up) it worked first time.

Now that it all seems to work, I’m going to bring it all along to Tankardstown Geopark next Sunday (17th) where SEARG will be operating for a few hours (80m Counties Contest) The priority will be voice on Sunday, but I may get time to “go digital”.

If your passing, drop in and say hello. Club members will be there from about 10 in the morning until after 6 in the evening.




Micro PV two years on.

Some changes since last year. Firstly the panels have a different orientation from last year.  I moved the shed last August/September and both panels are now facing South West (220deg), still at the tilt of about 5-10 degrees (which I really must measure), not ideal but better than before.

The same two Evergreen panels are in use, but I’ve a new Mastervolt Soladin Inverter from Nigel in Mysolarshop. Unfortunately I accidentally let the magic smoke out of the Steca, when moving things around and it had to be replaced. I might try and get the smoke back in some rainy afternoon when I’m bored. The measurement set-up is still the same using the Envi CC-128.

So for the last 12 months rrdtool is saying an ‘average’ of 28 watts is produced every day. So from the back-of-an-envelope, we get 0.028*24*365 or approximately 245 kWh produced, with a value of approximately €49.

However, I have reason to believe that output will be better this year. The first picture below is from the 3rd of June last year.

This one is from today:

Two things are immediately obvious. The peak instantaneous value, and the average are both higher. This should help increase the output from the system for 2012.

The experiment continues!

Micro PV, one year on.

So, after 12 months, what do the numbers say?

Well first a quick reminder of what I have running. A Steca Grid 300 from, fed from two Evergreen ES-180RL 180 watt PV panels on the roof of the shed.  They are fairly flat on the shed and not in an ideal location. There is about 5-10 degree of tilt on the panels.  One of them is ‘facing’ South East, the other North West. So a very non-ideal situation, but useful nonetheless.

I’m using rrtdool to graph the output from an Envi CC128. The CC128 is measuring the output of the Steca grid-tie inverter.

So for the last 12 months rrdtool is saying an ‘average’ of 35 watts is produced every day. So from the back-of-an-envelope, we get 0.035*24*365 or approximately 306 kWh produced, with a value of approximately €55. Not a whole lot really.

Looking at the ‘average’ consumed by the house. It is now showing as 391 Watts (down from 455 the last time I looked). Giving 0.391 *24*365 or approximately 3425kWh (approx €620).

In short, its knocking about 10% off the electricty bill at present, not a lot, but given the panels don’t receive any direct sunlight in mid winter, it isn’t bad at all.

The experiment continues.


Winter is most definitely on the way, slight frost on the car this morning, and the weather station run by the South Eastern Amateur Radio Group showing a significant dip last night, though it was colder on Sunday night. Strangely though, I’m looking forward to getting a nice fire going on our new stove. And seeing how well it can heat the sitting room and the rest of the house.

First Light

I finished off the rewiring i mentioned in a previous post.  This was mostly just a tidy up of the cables around the inverter. The inverter itself is an older model Powermaster PM-1500SL-24, however the battery charging circuit generates terrible Radio Frequency interference. This means that the shortwave bands are completely obliterated when charging is taking place (from either solar or mains/generator power), so I leave the inverter off unless I need it. I use a Steca PR3030 and two 80watt panels, facing roughly South, to keep the battery bank topped up.

I have tested the system it by running the central heating, fridge-freezer and chest freezer off the inverter for a few hours, but I must give it a more thorough test at some stage in the near future.  The batteries are no longer new and, should there be a power cut, I’d better be able to keep the TV running or the boss will not be pleased!

“Gorilla” Update

I’ve not been in the shack all that much recently (being part of the organising team the the Irish IPv6 Summit kept me busy) so I have not been doing much checking up on the PV installation and how it is working.  Today, after assisting the South Eastern Amateur Radio Group set up a station for the EI2GEO special event station, I got to sit down and do some investigations. I have a second 60 Watt solar panel that I mentioned before. We hooked it into the battery system on Jim, EI8IG’s camper van to keep the battery topped up via solar power, and ran the radio from the same battery bank.  This evening I dropped out my little 850 watt generator to keep the battery topped up overnight (and to give it a good run).

Today over a 12 hour period between approximately 08:00-20:00, my rrdtool graph says the system produced an average of 148 watts. 148 x 12 gives 1776kw, or approximately 28.5 cents of electricty (including vat). If we have about 7000 more days of sunshine like today  (unlikely) then the system will have “paid for itself”.  While it doesn’t seem like a whole lot, it is currently averaging about 1/6 of the ESB bill (over 30 days).

That is the first part done. Next I intend to replace my power hungry dell dimension desktop (approx. 125 watts, 24/7 or approx. 48 cents per day ) with a more efficient machine (approx 20 watts or approx. 8 cents per day). To do this I have purchased an Intel Pine Trail base D510MO a 40GB SSD drive, 4GB of ram and a DC powered case (I already have a DC supply in the shack, plus I can experiment with it in the car as well).

Thus far the machine seems to be able to do most of the tasks I need it to do, time will tell though as I need to get 6 RS-232 ports operational on it to control all the items I have running.

As an aside, we recently replaced the old washing machine (at least 10 years) with a super duper A rated new one.  Initial testing seems to suggest that it is no more efficient than the old one. My suspicion is that I tested the old one (which I no longer have) in late Autumn, where it would have the benefit of taking hot water from the cylinder (Central Heating). The new one doesn’t have a Hot water input, so has to heat the water itself.

Ramblings about PV and going “Gorilla”

Ok I admit, I’m a bit of a solar power junkie.  I’ve been experimenting with PV panels a while now (here, here, here, and here). I have a small 10 watt waterproof solar panel (the irony eh?) which I got a number of years ago that I use to keep a few GEL Cells topped up by leaving it in the window of the upstairs bedroom.  I have a pair of Evergreen ES-180RLs (24volt) which have been mounted on the shed roof for quite a while now, also, last year I picked up a pair of 80 Watt Panels (12 volts, off ebay) and a second hand 60 (12 volt) watt panel.

At the moment I’m using them to keep a battery bank charged. I have a 1500 Watt inverter/charger that I can run off the bank.  I split one of the circuits in the house so that I can plug it either into the consumer board, or the output from the inverter.  This circuit has on it, the central heating pump and burner, fridge, fridge freezer and one double socket in the kitchen, i.e. an extension lead can be run to the TV/Radio Shack.  This is just the way the house was wired, so I took advantage of it. I also have an external 220v connection that I can feed in the output of a generator. The inverter is plugged into this, and if it is receiving power from a generator, it can power the house circuit mentioned above and re-charge the battery bank simultaneously.  My only issue with the inverter is that when the charging circuit is running, it generates an awful racket on the HF bands. I’ve used it a few times during power outages, Watching T.V. when the rest of the housing estate is in darkness is interesting, and generates interesting questions afterwards (how come you had lights on etc.). I also can run the items in the shack directly from the battery bank, but, to be honest, it’s a bit messy, and not very efficient.

The 60 Watt I bring with me on AREN events, as its useful at keeping the battery in my X-Trail or the Mobile Command Post (MCP) topped up:

The 60 Watt panel works surprisingly well for this purpose.  On several (rare) sunny events in the last 12 Months, we didn’t require any generators or external power at all on the day.

Anyway, back to my main point.  I happened to visit John Ketch a few months back, and he was particularly happy with the advice he got from Nigel in as to panels and other items. As I had been thinking about getting a grid-tie inverter to experiment with, I took Nigels details and in February I rang him.

Our initital conversation was not what I expected. I outlined the various bits and pieces that I have, what they were doing etc, and said I was interested in getting a grid-tie inverter.  Nigel said to go away and think long and hard about what I’m trying to achieve and come back to him after I’d done that.

So, I go away and re-examined what I wanted to do.  Between the server and radio gear I leave running 24×7, plus the usual stuff like alarm clocks etc, I have about approximately a 400 Watts of continuous load in the house.  So I decided to do several things. Replace the server with something that uses less power, more intelligently use the radio equipment i.e. only switch it on when a satellite is visible, and see what contribution a grid-tie inverter could make to offsetting the usage.

Typically, I’m tackling the last one first.  So my plan was to split the panels, and use the two 24 volt panels with a grid-tie inverter, leave the two 12 volt panels to charge the battery bank.  So I rang Nigel again about a week ago. This time things went better, in that I actually convinced Nigel to see me an inverter! I went with a Steca Grid 300 from

Now,before agreeing to the sale Nigel pointed out that though the inverter does automatically shut down should the grid fail, it does not conform to EN50438, which the ESB require in order for any installation to be approved. I looked at the specs, and decided that in the grand scheme of things, my (potential) 300 watts isn’t going to make much of a difference, and that if he didn’t tell the ESB, then neither would I.

This morning at 08:00 when I plugged it in, the inverter was producing approximately 60 Watts, which I think is very impressive given the low light levels. It will peak somewhere between 180 and 200 Watts (based on yesterdays performance) about 13:00, and still be putting out 60 Watts at 20:00. I’m monitoring both the general house consumption and the output of the inverter with an Envi CC128, so it will be interesting to watch it over time.

So there you have it, I’ve gone “Gorilla”. Many thanks to Nigel in for the advice and assistance.