New Solar Kit Suggestions?

Re: New Solar Kit Suggestions?

Welcome to the forum Kevin!

You have asked a lot here... I will try to help with a 50,000 foot view. Please feel free to ask detailed questions at any time.

kevelev wrote: »

I was hoping someone may suggest for me a good place to start for a solar newbie like myself. I'd like to power an average sized apartment eventually.

We all started there... A desire and starting from ground zero.

Designing a cost effective system that meets your needs--We need to help you understand those needs. Assuming this is for normal 120 (and 240) VAC loads, we start with Watts of power. I.e., we have seen the 100 Watt light bulb. Run that for 2 hours, and you use 100w*2hours=200Watt*Hours.

A really nice and practical tool for understanding/measuring your energy usage is a Kill-a-Watt type meter (for 120 VAC 15 amp plug-in appliances). If will tell you your power (average/peak) (a rate, like miles per gallon). And your energy usage (amount, like gallons of fuel used on trip).

So--You create a list/spreadsheet of your loads, add them up (average wattage, peak wattage, average watt*hours per day) to size the equipment.

And, very quickly, you will see that our power usage is quite high, and the output for an "average" solar power system is quite low (and the equipment is expensive).

So, we come back to energy usage and recommend conservation. It is almost always cheaper to conserve power than to generate it (insulation, double pane windows, CFL/LED lighting, laptop vs desktop computer, energy star appliances, etc.).

It is not unusual for a home that has never looked at energy efficiency to reduce electrical power usage by upwards of 1/2 or even more.

Just to give you some ideas about energy usage--Assuming natural gas/propane/etc. for cooking, hot water, clothes drier--Some very rough energy usage levels for a North American home:

• 1,000 Watt*Hours (1 kWH per day or 30 kWH per month) for a small cabin (lights, laptop, cell charger, water pump, etc.).
• 3.3 kWH per day (100 kWH per month) add an Energy Star Refrigerator and a washing machine
• 10 kWH per day (300 kWH per month) add central heat, multiple computers/TV/kids/microwave/toaster oven, etc.
• 30 kWH per day (1,000 kWH per month) typical North American home (no special energy conservation)
• 30-100 kWH per day (1,000-3,000 kWH per month) add air conditioning, all electric home etc.

Most people in the US pay around $0.10 to $0.30 per kWH for electricity... An Off Grid system will cost (very rough) $1-$2+ per kWH (some people less, some people more--But something on the order of 10x the cost of utility power). So, if you already have grid power, you can see that going "off grid" can save a lot of money if there serious energy conservation involved.

A small system would be on the order of 1 kWH per day (roughly 500 watts of solar panels, a 300 watt AC inverter, and ~400 AH of 12 volt deep cycle batteries (something like ~4x 6 volt 200 AH "golf cart" sized batteries).

So, for a $1,000 (really rough number), you will get around a 1 kWH per day system... You would need ~2-3.3 kWH system just to power a refrigerator (~1.5 kWH per day) plus lights plus laptop (~0.5-1.0 kWH per day for computer + networking + printer).

I guess it would be nice to start with something small just to be able to power key equipment/appliances (full size fridge-freezer, computer, TV, 1 or 2 lamps & a fan or heater), but be able to expand it over time, so I may be able to get completely off-grid. I'd be willing to spend close to the $1,000 range to get me started. Either way, I'm totally open for suggestions on any level. Thanks everybody. Much appreciated.

In general, it is not really practical to "start small" and expand an off grid power system over time--There are just too many issues involved. When you more than double the size of a system, you probably have to "scrap" (or sell on Ebay) most of your original system, and start over again with the next higher "class" of equipment (larger/higher voltage inverters, larger/higher rated charge controllers, new/larger/higher voltage battery bank, new/larger solar array and mounting/wiring, etc.).

And, for somebody in an apparment where you are limited in your energy conservation (you probably cannot insulate the ceilings, change windows, install a new central heat pump / AC system). And you cannot mount more than a few hundred watts of solar panels on your balcony (to run a "typical" apartment off grid, you would need ~3,500 watt to >5,000 watt of solar panels (several hundred's of square feet of solar panels).

The scale of the problem just usually does not map back to an apartment system. And, if off grid, you would need a backup source of power (a 2-5kW genset, fuel storage, etc.) for winter when you have a week of no sun (batteries will only store around 2 day worth of energy for a "balanced" off grid system).

More than happy to go into the details of any of the above areas of interest (lots of suggestions, math for sizing of equipment, etc.). But this will not be a small system or a small project.

To power my (reasonably efficient) San Francisco suburben home (central heat, no A/C, natural gas, adding insulation for ceiling, exterior walls, floor, double pane windows, operating skylights, etc.). And a 3.5 kW Grid Tied at ~$15,000 for today's pricing (no battery/off grid power) system gives me lots of power--around 300-400 kWH per month (I have excess power at the end of year billing cycle). And off grid system would need a bigger array, plus batteries, charge controllers, AC inverter, etc... would cost 2-4x as much.

P.S. I'd also like to know about lifespan of certain equipment available here, if possible, also. (Do panels typically need replacing over time? How long will solar batteries hold a charge when NOT in use?) Thanks!

Very rough numbers:

• Batteries last 5-8 years, but can die in 3-5 years ("inexpensive" batteries "run hard") or even days/months if mistreated
• Charge Controllers, AC Inverters, other electronics--Plan on replacement every 10+ years (hard to repair 10+ year old electronics)
• Solar arrays--Good quality Glass panels with crystalline solar cells should easily last 20+ years (perhaps 30-45 years).

For a good read--Take a look at this Thread. Lots of information, links to other sites, and some projects:

http://forum.solar-electric.com/showthread.php?5556-Working-Thread-for-Solar-Beginner-Post-FAQ

Please feel free to ask questions--The above are very rough rules of thumbs and my assumptions about your life--I may very well be mostly wrong on many of my guesses. Energy usage is highly personal and we try to give practical answers that help people meet their needs.

-Bill

Re: New Solar Kit Suggestions?

Christine,

I read your post and comments to people asking questions about solar power--And I have no disagreements with what you said.

There are places out there that have spread sheets and on-line forms where you can enter the information and get some answers.

https://www.google.com/search?q=off+grid+solar+calculator

And our host has some information and a spreadsheet:

http://www.solar-electric.com/elloevwo.html

There is really no substitute to measuring your loads and understanding the numbers behind the measurements...

• Kill-a-Watt Measure plug-in AC loads (Euro versions available too)
• The Energy Detective Measure whole house loads
• Doc Wattsun Measure DC loads (~20 watts maximum, 60 volts maximum)
• AC/DC Current Clamp Meter (measure larger AC/DC load current and estimate power)

The above links are just examples--There are many different websites and tools for doing these measurements.

-Bill