Planning a new home & solar - Need Help

Re: Planning a new home & solar - Need Help

Welcome Doug,

First three recommendations are conserve, conserve, and conserve.

Solar power is not cheap--so anything you don't need to power, means your solar installation can be just that little bit cheaper--and you avoided paying that 1 extra kWhour every month, for the next 30 years.

Check out Home Power Magazine for ideas on conservation and home design.

Next, once you have figured out your monthly (and seasonal loads), you need to check with your utility company to see what kinds of power plans they have...

Some don't allow grid tie connections at all. Some just pay you the wholesale rate for electricity (typically, around 1/4 the retail rate)... Others will have 1 month or 1 year net metering plans--basically, add all of your usage together, and all of your generation. At the end of the period (1 month or 1 year), you pay what you owe (if negative balance) or, if positive balance on the bill, the power company "eats" your "profit" (you buy/sell power at retail).

The 1 year net metering is probably the best residential plan out there.

Also, there are flat rate and time of use plans. Depending on your power consumption pattern--Time Of Use may help you (for me, I sell power in the afternoons at $0.30 per kWhr, and buy back power off-peak at $0.09 per kWhr).

Once you have the approximate monthly power requirements--then you can size the array with this online Solar Power Calculator (use the defaults for a start). There is also a PDF version of the data so you can see how your sun varies over the seasons and the years.

Next, you can see what rebates/tax credits there are for your location.

Next, what vendors are good? Check out NAWS' store (our host, "WindSun"). They do a pretty good job of only selling some of the better vendors out there, and will remove those (from their website) those vendors that fail to perform. There are also FAQ's and other links for useful information.

Cost wise, your choices for solar power--

• 0. Conservation. Insulation, Windows, EnergyStar appliances, more insulation, site-ing of home & window/overhangs, etc.
• 1. Solar Hot Water--typically the best $$$/watt (although, plumbing issues; leaks, seals, pumps, controllers, etc. make the maintenance an issue.
• 2. Solar PV Grid Tied... Simple grid tied can get close to the cost of utility power (especially after rebates). Little maintenance required.
• 3. Solar PV Grid Tied with backup batteries... Can increase the cost of power by 2-4+ times because of cost of batteries, charge controllers, battery replacement, backup generator (if wanted), etc.
• 4. Solar Off-Grid... Somewhat more expensive than #3--because you cannot backup 1 month or 1 year of power (through grid tie and net metering).
• 99. Wind Turbine.... Possibly good for stormy weather and very windy locations.

Just to give you an idea of costs... (retail pricing including installation and permits, really wild guesses)...

1. Solar Hot Water for 9 months of the year--$5-$10,000 for four people
2. Grid Tied Solar... ~$0.15-$0.35 per kWhr
3. Grid Tied Solar + backup batteries ~$0.50-$1.00 per kWhr
4. Off Grid Solar ~ $1.00+ per kWhr
5. Wind Turbine ~Priceless (OK, joke--maintenance issues and poor performance plague large numbers of small installations).

Conservation--That is so location and owner specific.

Off grid users, probably aim at less than ~100 kWhrs per month.

In moderate climate, (my home south of San Francisco)--for electricity I use ~200-250kWhrs per month and a 3kW rated (3.5kW worth of grid tied panels, for ~$28,000 list price, before 1/3 rebates) generates way more power than I am currently using.

For people with extreme temperatures--1,000-2,500 kWhrs per month during heating/cooling seasons is not out of the ordinary... Cutting those numbers, before thinking about solar, is important (solar PV installations are expensive).

Questions?

-Bill

Add, solar panels, especially solar PV electric panels, need absolutely clear access to the sun from ~9am to 3pm... Any shading will reduce output... And for solar electric, a power line running across the panels, or a single panel shaded by a vent stack or building facade can easily cut output of an entire array by 50%.

Watch for potential issues... That cute little tree on the property line will grow up. That neighbor with the 1 story home, will eventually have 6 kids and add a couple stories, etc.

Of course, lots of this stuff is rule of thumb type information. Local conditions can impact design... For example, hot afternoons with clouds--facing the array more towards the South East may increase your output. Early morning fog, then a westerly array may be better.

There is no "right or wrong"--just things, if not done correctly, will cause you to lose output... A lost 1kWhr per day x 365 days x 25 years all adds up.

Re: Planning a new home & solar - Need Help

Mine works (for me) because I am grandfathered under the old E7 plan--which has one peak period from noon to 6pm, Monday thru Friday.

The new plan, E6, has a very complex TOU schedule:

TIME PERIODS: Times of the year and times of the day are defined as follows:

Summer (service from May 1 through October 31):

Peak: 1:00 p.m. to 7:00 p.m. Monday through Friday
Partial-Peak: 10:00 a.m. to 1:00 p.m.
AND 7:00 p.m. to 9:00 p.m. Monday through Friday
Plus 5:00 p.m. to 8:00 p.m. Saturday and Sunday

Off-Peak: All other times including Holidays.

Winter (service from November 1 through April 30):
Partial-Peak: 5:00 p.m. to 8:00 p.m. Monday through Friday
Off-Peak: All other times including Holidays.

Holidays: “Holidays” for the purposes of this rate schedule are New Year’s Day, President’s Day, Memorial Day, Independence Day, Labor Day, Veterans Day, Thanksgiving Day, and Christmas Day. The dates will be those on which the holidays are legally observed.

DAYLIGHT SAVING TIME ADJUSTMENT: The time periods shown above will begin and end one hour later for the period between the second Sunday in March and the first Sunday in April, and for the period between the last Sunday in October and the first Sunday in November.

And, if I had a choice between flat rate and E6--I probably would choose the flat rate because the E6 TOU runs into when we cook dinner and is just plain too complex to explain to the family and have them "follow" the rules.

I probably would do better on E6 vs E1 flat rate--but I don't want the exposure to what happens if I mess up.

The rules between E1, E6, E7, E8 have constantly been changing... Originally, I had a choice, then new users had to pick E6, then back to a choice among all, for new users--for a bit of time. Then back to a choice between E1 and E6. Just a huge mess.

But, I see the utility's side too...E6 does a better job of mapping utility costs against when peak usage really happens... During some parts of the year, a second peak daily usage occurs around 8pm. E7 is much more favorable towards the customer with solar power.

But, that will probably all change in the next couple of years. They are starting to install "smart meters" (remote read) that can support any rate plan (with one meter), but also a "real-time pricing plan".

And, as I understand, as a grid tied solar generator, I will be required to convert to the new plan... Where times and price change every 24 hours, with 24 hour notice (I think).

This is going to be a nightmare... I have no idea how this is going to work. The exposure to "making a mistake" and turning on the wrong appliance at the wrong time will quickly add up... For example the current summer rates (E6 as an example) range between $0.09 to $0.58 per kWhr. For those people with large electric loads (all electric homes, A/C, etc.) may be in for real shocks when this plan rolls out.

The new real-time billing rate may be optional for non-RE equipped homes--but will most likely be required for Grid Tied RE homes (or, we may have to pay reservation charges, which are their own can of worms that may end up punishing GT RE homes with larger arrays--not sure about that yet).

I have no idea how anyone will be able to calculate a rate of return for a solar GT installation when this happens.

It will be a "brave new world" for Californians coming in the next few years.

-Bill

Re: Planning a new home & solar - Need Help

In the end, get the parts list of major components (inverter, solar panels, rails) and understand what the warranties are and and special issues (tile roofs, running of conduit, etc.).

A poster here has his own forum (solar guppy's forum) and has some great sections on Solar Panels and other components discussing reliability and other issues. SG designs GT Inverters and other devices--so he has lots of direct experience to talk about various issues around solar RE products.

If the components are good quality, the companies backing them will be around for warranty service (not sure anyone can guarantee that anymore) and there is nothing proprietary (solar panels that use special plug+rails so 10 years later repair/upgrades are a hassle; odd-ball inverter connections or voltage requirements, etc.)--then local installer price and reference checks are probably the most important.

For the run-of-the-mill Grid Tie install, there is not two much that makes it important to match a package of components together (pretty much any good quality panel will work with any good quality GT Inverter which will work with any standard breaker panel).

If you will be into computer monitoring--there is quite a bit of variability between vendors in the available monitoring connections, software available, and costs to monitor.

If you are looking for a Hybrid System (GT and Off-Grid capable), I would first suggest looking at Xantrex and Outback and stay within the mfgr's family. I would avoid mixing components between vendors. Having a common communications bus (between inverter, solar charger, AC charger, autostart for generator, etc. and the ability to point at one vendor and say "I don't care which component is acting up--fix it" is sometimes very handy.

If you are looking at GT Inverters, any of the vendors listed here is a good place to start (Enphase is brand new--interesting concept, but probably not cost effective for larger systems).

Lastly, you mentioned that you are thinking about migrating from GT to GT with battery backup... In general, it is very difficuilt to "grow" and "morph" RE systems in size and function.

A change from GT to GT+Battery would include the need to rewire the array from ~200-600 VDC to ~65-140 VDC. You would need to replace the GT inverter with a Hybrid GT/Off-Grid Inverter (plus rewire your AC to include a transfer switch for your protected loads), add Solar Charge Controller(s), and install a battery bank.

About the onlything saved are the panels themselves (although, the rewiring may mean that you need a couple extra, or drop a couple to match the string voltages/currents with the change from High Voltage GT Inverter to medium voltage MPPT solar charge controllers).

My recommendation is that you don't plan on morphing your system--but plan for exactly what you want/can afford. You may be able to oversize the Inverter and add panels later (watch the series/parallel connections as you add panels)--but that is your choice.

-Bill

Re: Planning a new home & solar - Need Help

Doug,

There is a section about one meter Net Metering that is much newer than the rest of the document.

There also is an older section which talks about charging and paying for power (two meters, one read forwards, the other backwards).

The newer section is about a net meter which runs forwards/backwards and they just read the net value once per month.

That second one is what you want. I could not find anything about how the net reading is managed if you generate more than you use...

For me (Kalifornia), we get paid "retail" for our excess power generated, and it goes into the "bank". After 1 year, the amount detected from the bank (winter) and the amount added to the bank gives either a net consumed bill (I pay). Or a net generated bill (balance is lost).

At worst, you have a 1 month net metering state... if you use more than you generate--normal bill. If you generate more than you use (over the one month), you only pay the minimum connection charge (around $7-$8 per month).

If you get a generation credit--it may be at the "commercial" rate (yep, really low) or at the retail rate (like done in my state)... But your power rates are really low anyway ($0.06-$0.08 per kWhr).

So, your low utility payments for generated power makes sense (they only pay you for the cost of power--the utility still makes their margin on charging you for the cost to distribute the power).

In any case, your cost of power is CHEAP... My cost of power $0.09-$0.37 per kWhr off-peak. $0.30 to $0.58 per kWhr peak...

Which would you rather have? Solar and $0.58 per kWhr, or no solar and $0.06 per kWhr?

As long as your rates remain low (for how long????), GT solar is not going to save you any money unless you have really good rebates (like 80%+ rebates).

With 33% rebates for my GT system, it still generate power around ~$0.15 to $0.17 per kWhr. Not even quite breaking even for me.

Where I saved money was in conservation (insulation, windows, appliances, CFL's, training kids).

For you, if saving money is important--Looking at solar hot water (and possibly solar thermal heating) may have a better return for you.

Since you are building a new home--looking at design/build issues up front--will help you way more than designing a "standard" home and bolting on GT solar after the fact.

Also, have you looked at a energy recovery system (for home ventilation)? If not, this may be a big help for you too.

-Bill