Sunday 25 January 2009

Devon Off Grid

We completed an Off Grid electricity system today. Consisting of 720 watts of Sharp PV monocrystalline modules mounted onto a custom made support frame, and a 1kW Futurenergy mini turbine on a 9 metre Altron tilt over tower.

Both these power sources have been designed to complement each other. When the weather is sunny and calm, the PV modules can push out up to 24 amps of power to charge the 540Ah battery bank, which runs a 1500 watt pure sine inverter.

Of course, there are many days in the UK, when daylight is low and bad weather rules, which is where the wind turbine comes in, keeping the batteries topped up while the PV modules struggle, and of course overnight the turbine comes into its own!

The whole system has been designed for a light load of A+ rated fridge, consuming only 150kW a year. Plus lights and TV/radio when required.

Keeping the batteries up to a decent voltage without too much loading is best for any off grid system to
ensure it will give years of low cost power.

Couple of images here.. The Concrete base with just cable duct and bolt studs poking out, and the other shot with tower base in position, with horizontal tower being painted.

Saturday 24 January 2009

Small Wind Turbine installation

Early in 2008, too late to take advantage of the Spring gales, we installed a small 1kW Futurenergy wind turbine with a grid connection.

Well... when I say we, it was a collaboration between the customer who made the tilt over tower, Michael from Kaieteur, and myself to get it all connected and running.

The location was ideal, being high and open, the only turbulance to interfere with the wind flow being the adjacent single storey buildings.

Installation was straightfoward as the customer had done all the hard work of installing a tower and prepared an area for the electrical equipment.

Within a day it was assembled and running. .. However, as the weeks passed it became apparent that the turbine output was not approaching what it should have been according to the manufacturers specifications. I installed a little wind speed and direction logger on site and direct reading watt meter to try and diagnose what the issue was.. After a couple of months of trying many different options, including the customer rebuilding part of the tower to gain height, the issue was simply the pitch pins supplied in the turbine kit were incorrect for the power curve we were trying to achieve.

Manufacturers sent us some alternative 25 degree pitch pins, and all is now working well.

As you can see from the picture, the Mastervolt small G83 grid connect inverter was used again. This version is marketed as the Windmaster 500 and is ideal for the Futurenergy turbine as the voltages match to give an optimimum output.

In this installation we connected 2 in parallel, as the site so good for wind capture, the customer wanted to realise as much potential generation from the turbine.. Unless the installation site is exceptional, I would suggest installing a single inverter, as output will only get to the rated 1kW hign consistant high winds without turbulance.

Crediton Solar PV installation

A domestic 1kWp system we installed in 2007. The house was ideally suited for solar PV, facing due south and having no shading from trees or other buildings to worry about.

We used Kyocera PV modules on the Alustand roof mounting system. The brackets and rails from Alustand were straightforward and conventional to install, giving a neat job with lead flashing around the brackets.
Alustand mounting system does rely on a level roof and we found after installing, even this 'straight' roof had undulations and the roof system needed adjusting to allow the PV modules to drop into their location slots.

The result was very neat looking though when all finished.

Inside the loft area the G83 grid connected inverters were installed. At that time, the most cost effective option for small inverters for 1kWp systems was the Mastervolt Soladin 600watt units. As can be seen from the picture, 2 inverters were fitted with 4 of the modules connected to each.
A kWh meter (to log how many units have been generated) was installed adjacent to the fuse box downstairs.

We did find that a lack of digital display on the Soladin a bit of a setback when trying to evaluate performance, but certainly for a small budget G83 grid connect inverter price and performance is very good.