Selfsufficientish.com

After trying generating my own electricity for the last 6 years with a small array of solar panels and a small wind turbine I have come to a few conclusions. These might help anyone reading the discussion elsewhere about the forthcoming electricity blackouts.

1) Solar PV is very expensive and the yield (in northern UK) is very poor
2) Residential wind is very expensive and the yield (in residential northern UK) is even poorer
3) unit energy prices would have to rise by a factor of 20 to make it worth it.
4) even then you could only generate a very small portion of a normal domestic consumption
5) batteries and inverters work rather well

leading to my tentative solution to the potential blackout problem

if you are grid-connected, forget generating your own power, just charge a huge battery bank from the mains and use an inverter. Basically a big UPS. Forget high-current loads while the mains is off. (washing machines, kettles, heaters etc)

Hi there Dave,
The battery backup system is a good idea if you experience frequent blackouts. You could go even further and replace much of your wiring with 12volt to increase the amount of usable electricity you can get out of it. This would be particularly good in a third world situation where power outages are frequent. The wealthy in such places all have petrol generators, but a battery bank would be much better and probably cost about the same.

Since I am closer to the equator, PV panels begin to make sense, but for a stopgap, a battery bank is a good idea.

How is your system rigged up?
-Memphis Slim

I have 4 solar panels on my garage roof and a Marlec wind turbine on a scaffolding pole. The PV panels go through a BP-Solar charge controller into a battery bank of 4 x 110Ah batteries. This then goes through a 500Watt 12v to 240VAC inverter and meter via a cable into the house where it surfaces in my computer room. Over 6 years I have ruined the Marlec charge controller (useless anyway), 2 batteries, one data-logger and one inverter. I have generated 351 metered kWh in 6 years and spent man-months of my time on the system. I got nearly 18 amps off the panels once. The turbine is connected directly to the batteries as there is zero chance of it ever overcharging them :-) its most frequent output is zero. A poor 12v connection nearly burned my garage down too.

I have been down the 12 volt route and have now adopted a 120 volt system. This gives a number of advantages.
The cost of cable, rectifiers and inverters are reduced.
Losses in rectifiers etc are reduced by 90%.
120 volts dc can be used to power ordinary immersion heaters, electric kettles, washing machine heaters, etc albeit at a quater of their 230 volt ac rated power. Voltage controlled relays can be used to switch loads at predetermined voltages, (effectively a charge controller and dump load).

What about a big deisel Genny running off old veg oil??



nb. Memphis Slim,now what a gig that was nearly 40 years ago!