Old Project Avalon Forum (ARCHIVE) - View Single Post - Solar power system goes live at Anchors house

Anchor · 11-30-2008, 07:11 AM

Portable PV

My main house power backup system is based on a 3Kw inverter, 300Ah batteries, 75A charger. There is no solar on this system yet because I rent and I am not allowed. The plan is later on that this system will be augmented with a combination of Solar and Wind; but it has to wait for early next year when I hope to move and get that all sorted out. (I quite realise that I may be cutting it fine

)

In the mean time, my objective in having a portable PV system was that I could take my system from place to place. Its a bit like the systems you would have in an RV or campervan.

The main reason for the system is to provide power for such things as:

Recharging batteries for everything battery powered. (This includes almost ALL my power tools which are 18V battery powered and recharge from a car charger)
Powering Laptop
Radio scanner
CB and HF Radio etc
Radio and possibly TV/DVD
Lighting
12V Fridge (not yet purchased)

Whenever I buy anything electrical these days I always ensure that it can run from a car 12v outlet. However this has not always been possible, so my system includes a small (600W) sinewave inverter.

The system starts with the 2 x 2 folding solar panels. Each is made of two 40W panels that are hinged and have fold out stands on them. Thus the total capacity is 2 x 2 x 40W = 160W. They have a design life of 20 years. The reason I chose two instead of one larger one, is that using the pair I have, I can adapt them if needed to trickle charge my 24V "home" system in an emergency.

For each folding panel the output of each panel is connected together in parallel into an Anderson plug. My first job therefore was to make a Y cable so that I could combine the output of both pairs of panels. From there I used an 8 gauge wire pair to take the power to the regulator. You need thick cables to minimize voltage drop.

The combined output goes into a Powertech 20A 12V regulator. Regulators are essential unless you have a truly gigantic battery capacity compared to the current output of your panels. The idea of these regulators is to ensure that the batteries don't get overcharged which shortens their life (or kills them). For my portable setup I have only one 12V battery (gel) at 50Ah capacity (18Kg!), so it is important to have a regulator. If I had a 260Ah or more battery (which would weigh about 90Kg), I could probably get away without one, but even then using the battery to regulate itself does shorten its life a bit and I don't recommend it. Batteries are such an incredibly expensive item that the investment in a regulator is worth making. If you get a good one with a computer in it, it can tell you interesting facts about the battery voltage, how much power has been harvested today etc.

Here is the one I use for the portable rig.
http://www.jaycar.com.au/productView...Max=&SUBCATID=

Finally the output of the regulator is connected to the battery.

I made a wiring harness for my battery as follows: The terminals of the batteries are connected to big cables (20mm² conductor) for the inverter - I soldered an Anderson plug at the free end. The positive side goes via a 100A fuse. You should always put fuses in anything connected to a large battery because they are capable of delivering huge currents should any electrical short circuit occur, enough to cause fires, destroy batteries, cause explosions, and end up with expensive smelly and smoking wreckages of your secondary PV components.

The Anderson plugs used in the system are found are these ones. They are all the same to keep everything interchangeable. They are expensive but I like them as they are quite safe.

http://www.jaycar.com.au/productView...Max=&SUBCATID=

Into this harness I wire a Euro style merit plug and a conventional car lighter socket. These are soldered in at the Anderson plug end, not the battery terminal end. Even so, they are separately fused at 20A each. This allows me to power 12v devices direct from the battery.

Provided the cable runs are short, it is more efficient to power devices direct from 12V, rather than use the inverter to create mains and then a transformer/power supply to power your stuff. Even the best inverters are only 90% efficient - and that is only when they operating at full capacity.

My powertech inverter is only 85% efficient at 600W. The one I have is an older model. The current model is here:
http://www.jaycar.com.au/productView...Max=&SUBCATID=

To power my laptop I don't use the inverter, instead I use one of these:
http://www.jaycar.com.au/productView...Max=&SUBCATID=

I am sorry I didn't take pictures of the test today. Maybe I will do that later when I get it all out again.

If you have any questions, let me know and I will try to answer them.

Please don't wire this stuff like this up yourself unless you have a good understanding of the electrical theory involved and the safety considerations necessary. Big batteries are very dangerous and can be impressively destructive when misused

Remember "current kills".

A..

11-30-2008, 07:11 AM	#12
Anchor Avalon Senior Member Join Date: Sep 2008 Location: Sydney, NSW, Australia Posts: 2,280	Re: Solar power system goes live at Anchors house Portable PV My main house power backup system is based on a 3Kw inverter, 300Ah batteries, 75A charger. There is no solar on this system yet because I rent and I am not allowed. The plan is later on that this system will be augmented with a combination of Solar and Wind; but it has to wait for early next year when I hope to move and get that all sorted out. (I quite realise that I may be cutting it fine ) In the mean time, my objective in having a portable PV system was that I could take my system from place to place. Its a bit like the systems you would have in an RV or campervan. The main reason for the system is to provide power for such things as: Recharging batteries for everything battery powered. (This includes almost ALL my power tools which are 18V battery powered and recharge from a car charger) Powering Laptop Radio scanner CB and HF Radio etc Radio and possibly TV/DVD Lighting 12V Fridge (not yet purchased) Whenever I buy anything electrical these days I always ensure that it can run from a car 12v outlet. However this has not always been possible, so my system includes a small (600W) sinewave inverter. The system starts with the 2 x 2 folding solar panels. Each is made of two 40W panels that are hinged and have fold out stands on them. Thus the total capacity is 2 x 2 x 40W = 160W. They have a design life of 20 years. The reason I chose two instead of one larger one, is that using the pair I have, I can adapt them if needed to trickle charge my 24V "home" system in an emergency. For each folding panel the output of each panel is connected together in parallel into an Anderson plug. My first job therefore was to make a Y cable so that I could combine the output of both pairs of panels. From there I used an 8 gauge wire pair to take the power to the regulator. You need thick cables to minimize voltage drop. The combined output goes into a Powertech 20A 12V regulator. Regulators are essential unless you have a truly gigantic battery capacity compared to the current output of your panels. The idea of these regulators is to ensure that the batteries don't get overcharged which shortens their life (or kills them). For my portable setup I have only one 12V battery (gel) at 50Ah capacity (18Kg!), so it is important to have a regulator. If I had a 260Ah or more battery (which would weigh about 90Kg), I could probably get away without one, but even then using the battery to regulate itself does shorten its life a bit and I don't recommend it. Batteries are such an incredibly expensive item that the investment in a regulator is worth making. If you get a good one with a computer in it, it can tell you interesting facts about the battery voltage, how much power has been harvested today etc. Here is the one I use for the portable rig. http://www.jaycar.com.au/productView...Max=&SUBCATID= Finally the output of the regulator is connected to the battery. I made a wiring harness for my battery as follows: The terminals of the batteries are connected to big cables (20mm² conductor) for the inverter - I soldered an Anderson plug at the free end. The positive side goes via a 100A fuse. You should always put fuses in anything connected to a large battery because they are capable of delivering huge currents should any electrical short circuit occur, enough to cause fires, destroy batteries, cause explosions, and end up with expensive smelly and smoking wreckages of your secondary PV components. The Anderson plugs used in the system are found are these ones. They are all the same to keep everything interchangeable. They are expensive but I like them as they are quite safe. http://www.jaycar.com.au/productView...Max=&SUBCATID= Into this harness I wire a Euro style merit plug and a conventional car lighter socket. These are soldered in at the Anderson plug end, not the battery terminal end. Even so, they are separately fused at 20A each. This allows me to power 12v devices direct from the battery. Provided the cable runs are short, it is more efficient to power devices direct from 12V, rather than use the inverter to create mains and then a transformer/power supply to power your stuff. Even the best inverters are only 90% efficient - and that is only when they operating at full capacity. My powertech inverter is only 85% efficient at 600W. The one I have is an older model. The current model is here: http://www.jaycar.com.au/productView...Max=&SUBCATID= To power my laptop I don't use the inverter, instead I use one of these: http://www.jaycar.com.au/productView...Max=&SUBCATID= I am sorry I didn't take pictures of the test today. Maybe I will do that later when I get it all out again. If you have any questions, let me know and I will try to answer them. Please don't wire this stuff like this up yourself unless you have a good understanding of the electrical theory involved and the safety considerations necessary. Big batteries are very dangerous and can be impressively destructive when misused Remember "current kills". A..