New Solar Panel

[kadet]

To use a 24 volt panel efficiently you would want a MPPT controller.

I would suggest any PV would benefit from an MPPT regardless of system voltage but it's the Watts that really matter, an MPPT does't really help that much until you exceed 400 Watts below that the benefit vs the extra cost and lower life expectancy of an MPPT is questionable.

But having said all that I have an MPPT on my 80Watt panel as it is slightly more efficient on my partly shaded panel when parked in the driveway and I got it cheap

[Sumner]

To use a 24 volt panel efficiently you would want a MPPT controller.

I would suggest any PV would benefit from an MPPT regardless of system voltage but it's the Watts that really matter, an MPPT does't really help that much until you exceed 400 Watts below that the benefit vs the extra cost and lower life expectancy of an MPPT is questionable.

But having said all that I have an MPPT on my 80Watt panel as it is slightly more efficient on my partly shaded panel when parked in the driveway and I got it cheap

Yes we also have MPPT controllers on both boats. On the Mac with 200 watts and no place to put more I'll take any gain we can get from the MPPT. It can help regardless of the wattage, but as you said if you have space for more panels the money into panels will give you more amperage for the buck but sooner or later on a boat you will run out of room. One just has to figure out how they are going to use their boat. Day/weekend sailing you have a number of choices. For cruising we have tried to optimize everything we can.

I've never read about less life though before. Maybe as it is more complex? You can get a good one for under $200 for the panels you can fit on a Mac. Not really a major expense if you are out on longer trips. About 3-4 days on the anchor vs. paying for a marina slip because one needs elect. would pay for it. We paid about $340 for the one for the 480 watts on the Endeavour,

Sum

===================================
Our MacGregor 26-S
Our Endeavour 37
Our Trips to Utah, Idaho, Canada, Florida
Mac-Venture Links

[kadet]

Yes it is all good fun, I must admit I am using my s as the experiment till I get a bigger boat. Dream is to sail off to some remote places so power self-sufficiency is a hobby of mine Have 7 215Watt panels on the house and am amazed how must electrickery they produce.

Solar, Wind, Tow, Petrol/Diesel and the motor and in what combination is a question I always ask myself.

Dream boat me thinks will have at least 400Watt solar, 200Watt wind, 100Watt tow and a 3000Watt petrol generator with at least 500Ah battery bank. Even been toying with the idea of Lithium Cells.

Time to go chainsaw some trees after ex_Cyclone Oswald decided my garden needed a prune..

[Sumner]

... Have 7 215Watt panels on the house and am amazed how must electrickery they produce.....

We hope to go that route in the next couple years with the house. Are you connecting the panels to the city/house grid or keeping them separate and using them with 12 volt appliances or using an inverter and running a couple circuits that way?

I don't think we will tie ours to the commercial grid,

Sum

===================================
Our MacGregor 26-S
Our Endeavour 37
Our Trips to Utah, Idaho, Canada, Florida
Mac-Venture Links

[kadet]

Grid tie-in inverter we get 50 cents off our bill for ever kwh we upload to the grid. Old Government incentive to go green, now only worth 8 cents .

[Sumner]

Grid tie-in inverter we get 50 cents off our bill for ever kwh we upload to the grid. Old Government incentive to go green, now only worth 8 cents .

That is nice. In our town they will only give us 1/2 credit vs. what they are charging us and a lot of the install has to be done by a licensed electrician which drives the cost up. When I built the house I wired in a parallel circuit around the house with outlets under the 110 outlets with the intent some day using that circuit for 12 volt appliances and such.

I think we will go with batteries, that circuit and an inverter for some other circuits in the house that could be switch between our system and the city's if needed. We will stay hooked to them for the 220 volts for my shop equipment.

We might try and set the house up more like the boat. I might even make a 12 volt fridge and freezer similar to the one I made for the Endeavour,

Sum

===================================
Our MacGregor 26-S
Our Endeavour 37
Our Trips to Utah, Idaho, Canada, Florida
Mac-Venture Links

[DaveB]

Yes parallel with 12 Volt Batteries, twin 6volt house batteries would be in series. Didn't know I had to explain.
No one I know runs a 24V system on thier Mac.
Dave

12 volt house batteries in series.
The voltage after the regulator should be at tops around 13.8 volts with direct sunlight but this could be lower due to Battery charge or cloudy weather.

Hope you meant parallel as in series would be a 24V system

And again depending on the regulator things should be like this for a 2 stage charger.

13.2 - 13.6 on float depending on temp. (battery 90-100% of full charge)
14.4- 14.5 for charging (battery less than 90% of full charge)
Some a short burst at 15-15.5 for equalisation.

Most electronic regulators have 3 stage charging sometime 4 if they include equalisation.
Bulk - 14+
Trickle - High 13s
Float - Low 13s

[kadet]

Didn't know I had to explain.

You don't have to do anything and it was not meant to be critical, but the statement is confusing.

I have two 40 watt panels that have 12 guage wiring that goes direct to regulator than a Fuse buss that goes between regulator and two 12 volt house batteries in series.

Reads as a 24V system but your 13.8 volt charging reads as a 12V system.

As these forums are used for help and information by everyone not necessarily skilled in the area of elecrtickery I felt it needed some clarification. And I agree a 26ft boat does not need 24V but you never know how some ppl might rig things or special needs they may have.

Sorry if I offended not the intent.

[bartmac]

Interesting discussion re 12v and solar panels.We have both a Mac and slide on truck camper setup with 12v only (small 300watt inverter for TV in camper) DC to DC charging in the camper from the truck 12v system whilst the engine runs (also charges Mac on the road)......want to go the next step....new house limited 240v centrally located to serve fridge,washing machine etc and the rest 12vDC (can DIY as its low voltage).Able to use all our 12v operated/charged stuff and all lighting 12v Led....looking to not feed to grid as 8 cents currently is silly but maintain existing grid connection as backup and reduce need for large battery bank

[kadet]

Sorry bartmac we live in the Nanny Country, if you were in NZ then yes you could.

Fixed installations with low voltage cables are still required to be installed by a Licensed Electrical Worker (LEW) as well . Portable installations are not covered by the standard or legislation and refer only that the works be carried out by a competent person.

[bartmac]

Bugger....not sure it would let me use this word.Hadn't counted on that...ie needing a licensed electrician for 12v...OK rethink....limited 240v with a plug in 12v subsystem ie 240-12v step down transformers for led lights (not sure of most effecient voltage for LEDs)....can then up the battery system above 12v

[Ormonddude]

Cant you do a lot of the work and then just have a electrician sign off on it? I am sure a electrician will take credit for your work at a reduced cost over actually working.

[bartmac]

There's a saying here....."there more than one way to skin a cat"....having said that though I like to do stuff myself where I can

[kadet]

Sadly not in OZ under the legislation a sparky cannot sign off on work they have not done or supervised themselves. Supervision only applies to apprentices and they must hold the necessary training certificate.

Read for more info.

http://news.domain.com.au/domain/diy/wh ... 20ld9.html

[Sumner]

Here it can be different state to state. Where I live now a licensed electrician has to wire from the pole to the meter to the main outside box. From there you can do all of the rest of the wiring, but the building inspector inspects it. I did all of the wiring on the house (also plumbing --- licensed plumber has to connect to the city sewer) my self and the other couple houses I build.

If I hook to the city grid then they install another meter or a dual one that shows what I sell to them. Since I'm putting electricity into the grid they want a licenced contractor to do the work to make sure it is done right. I can see their point. The main thing I don't like is that if I use the grid as a battery and say put in a 100 kilowatts but want to take it back out later I can only take out 50 before they start charging me for any over that. So in essence if I think I need a 2000 watt array to power the house I might have to put in 4000 watts of solar if they are 'the battery' .

I'd rather spend the money on batteries and be independent if I want to at some point. I could even run a gen-set every once in a while when I welded and such. Elect. isn't that expensive now, but who knows where it will be 5-10 years down the road. Right now we can heat the house for about $200 a winter (in a cold climate at 6000 feet) and I think we can cut that further. With enough solar (probably about $4000) I think we can cut the elect. bill down to under $200 a year,

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links