where does a newbie start?

Re: where does a newbie start?

ydydxhg,

Are you somewhere out of New Zealand?

Question... Are you looking for for On-Grid (connected to your AC mains to save money on your utility power)--or Off-Grid where there is no AC power around and you just need solar, wind, water turbine, and/or fuel driven Generator for local power?

-Bill

Re: where does a newbie start?

There is no "right answer"--it really depends on your needs. But--solar Renewable Energy is not cheap (see here for some simple diagrams explaining various solar electric system options)...

Just to give you a rough idea (based on USD$ and US pricing):

$0.08-$0.30 per kWhr Utility Power
$0.10-$0.30 per kWhr Grid Tied solar PV (assuming 20+ year life)
$0.45-$0.70 per kWhr Grid Tied Solar + battery backup (assuming 20+ year life)
$0.50-$2.00 per kWhr fuel based AC Generator
$1.00-$2.00+ per kWhr Off-Grid solar (assuming 20 year life)

The above are very rough guesses at assigning a price for electricity from various power sources.

So--I would guess, that where ever you are, there is a ~10:1 ratio between the cost of grid supplied power and off-grid power.

If you have reliable grid power, then going off-grid is not going to save you any money in the foreseeable future.

If your grid power is unreliable (storms, insufficient capacity, etc.)--then some sort of battery backup (with or without solar power) is a common solution in many parts of the world.

If your utility will authorize a Solar Grid Tied Inverter system, and they offer you a competitive (i.e., subsidized) billing plan (in the US--typically, that is a 1-year net metering program... Basically, the meter turns forward if you use power, turns backwards if you generate power; at the end of one year, you either owe for the power you use, or don't owe anything if you break even or generated excess power--except a $5-$10 per month service charge).

Regarding building your own panels. Many people do it--but in the US it is not worth the trouble. In the US, you can buy "raw" solar cells for ~$0.50-$1.00 per watt on Ebay. And you can buy complete Safety Approved panels with 25 year warranty for $3-$5 per watt.

Home building your own panels that will last 25-40 years out of low iron tempered glass is probably near impossible (if they last a year or three--you are probably doing well). And many people build their own panels using plastic sheets. Which can be a problem when building larger arrays / systems (more than a few 10's of watts):

Panel Fire Question (pictures of array fire on home roof from plastic based solar panels)

If, you are interested in saving money--Spending your time and money on "extreme" conservation in/around your home is probably your first big task. Depending on where you live, and what your energy sources are (if you use non-electric sources for hot water, home heating, clothes drying, etc.)--Look at your current electric bill for how many kWhr per month you use...

The typical North American / European usage is probably around 600-1,000 kWhrs per month. The typical off-grid home probably uses less than 100 kWhrs per month. I find that 200-300 kWhrs per month is reasonably easy to do in my San Francisco CA USA home and family of four (no air conditioning, using natural gas for cooking, hot water, heating, drying).

Usually, spending your money in conservation is a much better return on your investment vs spending it on solar RE electric generation. Once you have done your conservation, then you can look at solar RE for your power.

One thing to look at is solar hot water -- most often this is the best return on investment of any solar RE project. However, it does come with a penalty of higher maintenance requirements (electric water pumps, leaky pipes, storage tank replacement over the years, etc.). And, in climates where freezing occurs--a more complex system with drain-back and/or antifreeze is required.

Next on investments is Solar Grid Tied electric (if allowed by your utility, and they have a good rate plan). Least amount of equipment and lowest maintenance requirements.

If you have backup power failure requirements--then a UPS (uninteruptable power supply--like used for computers) with or without solar power is a good solution. Can be small, just a few lights and a radio; or a whole house. There are some very nice Hybrid Grid Tied / Off Grid systems with Solar Panels and backup genset connections (see Xantrex XW system for an example).

Sort of down at the bottom, if you are in a windy location, is a Wind Turbine. Many are noisy, not very reliable, and expensive to maintain. Also, few locations are windy enough to support a smaller "home sized" wind turbine on their property. And small wind turbines rarely produce as much power as people expect.

-Bill

Re: where does a newbie start?

The PV Watts website has an entry for Auckland.

You can enter 1 kWatt of solar panels (1,000 watts) and see how much power it will generate for you (defaults = Grid Tied Power).

For off-grid power, enter 0.52 for a derating--and you can see how much an off grid system would generate.

For example, a 1kW GT system will generate:

70-137 kWhrs per month (winter-summer)

A 1kW Off Grid system (0.52 derating) would generate:

46-91 kWhrs per month (winter-summer)

-Bill

Re: where does a newbie start?

nissnutt,

Two steps...

1. Understand your load--What is your peak, average power (watts), and your long term average power usage (Watt*Hours or kWatt*Hours per day/month).
2. Determine if you can cost effectively use Grid Tied Solar Inverter, or if you need to use a Hybrid/Off-Grid solar system.

The best use of your money (after solar thermal) is Grid Tied Solar. Just solar panels + a Grid Tied inverter to feed your home and (if allowed) turn your meter backwards during the day. However, many utilities/countries do not allow Grid Tied (Utility Interactive) Inverters to be connected... First reason is safety (should not be an issue with modern GT inverters). And the second--utilities don't make money by purchasing your electricity at retail, only to sell it back to you, at retail, later that evening.

So, that leaves you with an off-grid implementation that can use the Grid for backup power.

Can be done, but certainly much more expensive than Grid Tied (see US comparisons above), or many times, more expensive than even expensive utility power.

In many countries (including the Caribbean)--you know better than I--that people will use an inverter+batteries for backup power because the local power is unreliable, or is turned off to certain areas during the day (rotating blackouts).

The last issue is solar panels are big, easy to break, and expensive... Would hurricanes threaten your array? Would vandalism and/or theft be a problem?

Working the conservation side, so you use as little power as practical--allows you to keep your system smaller and less expensive too (and, if you use expensive utility power--that usage is reduced too).

Do want to move this to your own thread?

-Bill

Re: where does a newbie start?

nissnutt,

That is certainly close enough to start. Let's use Puerto Rico as being roughly equivalent weather wise:

340kWhr per month or 14kWhrs per day, Grid Tied, 1 kW array, Default Settings:

[FONT=Fixedsys]Month
Solar Radiation (kWh/m2/day)
AC Energy (kWh) 
Energy Value ($ @ $0.117 per kWhr)
1      5.16          112        13.33   
2      5.58          110        13.09   
3      6.08          132        15.71   
4      5.97          125        14.88   
5      5.50          118        14.04   
6      5.62          118        14.04   
7      5.75          123        14.64   
8      5.78          123        14.64   
9      5.85          121        14.40   
10     5.40          116        13.80   
11     4.85          101        12.02   
12     4.77          102        12.14  
========================================= 
Year   5.53          1400    166.60 [/FONT]

So, assume your solar panels will power your home 9 months out of the year (without utility or generator backup):

That would set January at 112 kWhrs per month for the minimum panel/array size:

345 kWhrs per month/112 kWhrpermonth for 1kW array = 3.1kW array (3,100 watts)

If you wanted to do the same calculation with an off grid (battery based) system, use a derating factor of 0.52 and you will find that January 1kW 0.52 array would give you 74 kWhrs per month.

345 kWh/ 74kWhr = 4.66kW array (4,660 watt array)

Battery wise:

14,000 Watt*Hours * 3days storage * 1/50% max discharge * * 1/85% eff inverter * 1/48 volt bank = 2,060 Amp*Hours @ 48 volt bank

The above numbers are very rough... But give you an idea of how much solar panel + battery you will need.

The above have a bunch of assumptions--all of which can be adjusted to better fit your needs.

Questions?

-Bill

Re: where does a newbie start?

You can define your needs any way you see fit...

The only connections are the ratio between the size of your solar panels and the AH rating of the battery bank. Typically, the Array supplies around 5% to 13% of your battery bank's 20 hour rating. For example, assume 13% charge ratio, 2,060 AH @ 48 volt battery bank:

• 0.13 * 2,060 AH * 48 volts = 12,900 watts of solar panels
• 12.9 kW of solar panels (for the battery bank recommended) would be about the maximum you would want to use before adding to battery bank size (to avoid overheating the battery bank and/or just wasting solar panel capacity).

And the rating of the battery bank vs your loads (too heavy of loads and/or too deep of discharge can damage the battery bank).

And, the above rules of thumb are just to get you "in the ball park" for rough sizing of your system... You can make changes which will affect the overall design requirements:

• AGM batteries are more efficient (and costly) than flooded cell batteries
• 1 or 2 axis arrays can gather more electricity, at the cost of a more expensive panel mounting system
• Less efficient MSW inverters are less costly (but can damage some motors/appliances)
• Using more of the power during the day (optional loads like pumping, washing cloths, A/C) can allow a smaller battery bank.
• Using a generator/utility power for "heavy" loads (shop tools, A/C) and use the solar for smaller loads at night (quiet operation time).

Just a few of the trade offs above that can affect your choices. I certainly do not have all of the answers (I find that I have few of the answers in life--but that is different subject :roll: ).

-Bill

Re: where does a newbie start?

Yes, they are covered with about 1/8" tempered glass (~3.5mm) (roughly the thickness of ordinary window glass).

I was referring to the fact that a large array is several hundred square feet of "glass roof" (basically like a green house roof--only much more expensive)... Could be wind born debris or human born.

If you don't have any issues with that in your area--then not a problem.

-Bill