starting up my solar life

[rick duvall]

I am and avid follower of your posts.. my wife and i are moving off the grid -- we will be self sustained -- my plan is to diy my solar == by all the calculators available on line, conservative estimates for our needs will be 4000 watts per day with 6.5 hrs of sun avg.. -- freezer, fridge, radio, lights. i do have full sun no shade in the location of my panels -- the system I think and stress I think will fit my needs is the MPP 24v 2.4kW PIP Model listed on your website using the 24v lifo4powerwall my questions are these:
1 is this configuration sufficient
2 how many panels should i use ==24v 100w or higher -- prefer to parallel the panels

 

[MisterSandals]

4000 watts per day with 6.5 hrs of sun avg

Assuming you meant 4000 watt hours
4000wh/6.5h = 615w of panels (assuming 100% efficiency)

How much of this power will be used outside the sun/charge times? This will determine how much battery(s) you will need. Also how many days do you want to be able to run off of batteries when the sun is not shining?
Will you have an alternate way to charge batteries like with a generator?

24v 100w or higher

Do yourself a favor and buy some big cheap panels on craigslist. Using tiny panels to build a big system is ridiculous. You can probably find big panels for $.50 per watt as many many others have.

Then when you have your panels and batteries figured out, look for an SCC that in compatible with them and preferably optimized to work well with them.

And FWIW, i think 4000wh quite a bit on the low side for running household appliances. Are you sure you figured those out properly? My gut feel is that you'd need around 2000w of solar minimum (x6.5h = 13000wh).

 

[Craig]

Assuming you meant 4000 watt hours
4000wh/6.5h = 615w of panels (assuming 100% efficiency)

How much of this power will be used outside the sun/charge times? This will determine how much battery(s) you will need. Also how many days do you want to be able to run off of batteries when the sun is not shining?
Will you have an alternate way to charge batteries like with a generator?


Do yourself a favor and buy some big cheap panels on craigslist. Using tiny panels to build a big system is ridiculous. You can probably find big panels for $.50 per watt as many many others have.

Then when you have your panels and batteries figured out, look for an SCC that in compatible with them and preferably optimized to work well with them.

And FWIW, i think 4000wh quite a bit on the low side for running household appliances. Are you sure you figured those out properly? My gut feel is that you'd need around 2000w of solar minimum (x6.5h = 13000wh).

I agree with everything above except that 4000 wh is not enough. It could be plenty or it could be horribly not enough. At home without any conservation I use 10Kw per day on my off grid with conservation I use less than 2Kw per day.

But I do agree make sure you know what you need 4k may or may not be enough.

 

[rick duvall]

thanks for the replay -- i do have a generator -- 4000watts --
I will have a fridge - 52 watt rating aprox. 1300 for the day
refridge -- 50 watt rating 1200 for the day
water heater is non electric propane -- household is fire place and rocket mass
as for additional power needs lights tv and radio i figured about 1800 watts for the day
the mpp I had in mind was a 24v volt all in one
the battery a 3kwh from bigbattery.com
2 day back-up would be ideal-- as I do have the generator
I was thinking of 24v at least 200 ah panels
again thank you

 

[MisterSandals]

the battery a 3kwh from bigbattery.com
2 day back-up would be ideal-- as I do have the generator

A 2 day backup would be twice the size of your daily use (2x 4kWh).

I was thinking of 24v at least 200 ah panels

200ah x 24v = 4800wh (what is this for exactly? ah panels?)

 

[rick duvall]

see how much of a newbie I can be -- 200 watt panels

 

[rick duvall]

I would also seriously consider checking the anual average wind speed where you intend to move, wind power is amazing, and cheap compared to solar, but you have to have at least 10 mph wind speed average annually to be worth while IMO, and that is running at 12 volt, so the micro turbine doesn't have to spin as fast to begin charging the battery. I would also seriously consider using an automatic solar tracker, on a duel axis mount. They only cost about 100 bucks and give you 30 or 40% more sun daily. A single tracker is rated for 1000 watts in panels. Here is a link to one of my video tutorials, I linked you right to the view of my home made solar trackers, its so easy, and they are 3 years old now, having survived a few storms already.

will chk into wind

 

[svetz]

... our needs will be 4000 watts per day with 6.5 hrs of sun avg..

That average might bite you.

Take a look at a solar insolation calculator for where you live. Let's use an example for sunny Centennial Colorado where I used to live with the panels tilted for optimum yearly performance.

Jan	Feb	Mar	Apr	May	Jun
4.26	4.84	5.57	5.61	5.80	5.90
Jul	Aug	Sep	Oct	Nov	Dec
5.71	5.59	5.87	5.59	4.51	4.11

"Insolation" is the equivalent amount of 100% power you get on a clear day over the course of a day. Typically you only get 100% power around solar noon for 20 minutes, 80% at 10 am and so on... an insolation number gives you an easy way to figure the maximum amount of power you could get over the course of the day.

In the OP you said you wanted 4 kW over 6.5 hours, or 4x6.5= 24 kWh/day. I saw the other posts where they assumed you were using 4 kWh/d, but a 4 kW generator makes me think you want more and 24 kWh/d isn't much power at all. (A single 60 watt bulb burning all day consumes 1.5 kWh/d).

In December, to get that in Centennial, I would have needed 24 kWh/d / 4.11 h/d = ~6 kW array minimum. That assumes the original 4 kW factored in losses for the battery round trip and inverter losses. The generator is a good idea, but make sure it's power output won't blow the inverter.

If you really only need 4000 wh / day consumption, assuming 90% inverter efficiency and 90% battery round trip that's 4000 / .9 / .9 = 5 kWh, and with an insolation of 4.11 that's 5000 / 4.11 = an array size of 1.2 kW.

What I see on my array is about what the insolation says on average... on rainy days I can see none and on clear days I can see more. So, you'll want to add some buffer to your battery and possibly a couple extra panels.

... prefer to parallel the panels...

On a 6 kW array that won't happen. But, the FAQ has a lot of information for setting up arrays in serial and parallel along with MPPT information.

Hope that helps and good luck!