Solar panels, a realistic solution to charging?

[MarkR]

Photovoltaic panels make sense if your home has the right kind of sun exposure (southern is optimal). You can maximize the energy available to your car by minimizing the energy demands of your home. Solar hot water system usually have the quickest pay back time. Solar-assisted a/c systems are pricy, but can be hyper-efficient.

The payback time for our purchased system was less than 5 years. The out-of-pocket cost for our 3,000 sq. ft. home for the PV panels was $11k after incentives, rebates, tax credits. We currently produce more energy than we use, but will have to reassess after the S arrives. It's MUCH cheaper with solar.

 

[NuclearPowered]

Photovoltaic panels make sense if your home has the right kind of sun exposure (southern is optimal). You can maximize the energy available to your car by minimizing the energy demands of your home. Solar hot water system usually have the quickest pay back time. Solar-assisted a/c systems are pricy, but can be hyper-efficient.

The payback time for our purchased system was less than 5 years. The out-of-pocket cost for our 3,000 sq. ft. home for the PV panels was $11k after incentives, rebates, tax credits. We currently produce more energy than we use, but will have to reassess after the S arrives. It's MUCH cheaper with solar.

Who installed your system?

I had a similar experience. It costed me 8.5k to go full solar after rebates and tax credits. I haven't payed an electric bill over 20 dollars since. My system size is 5.28 kw, it makes about 32-35 kwh/day. Payback was 8.5 years, but that was conservative.

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[SCW-Greg]

Photovoltaic panels make sense if your home has the right kind of sun exposure (southern is optimal). You can maximize the energy available to your car by minimizing the energy demands of your home. Solar hot water system usually have the quickest pay back time. Solar-assisted a/c systems are pricy, but can be hyper-efficient.

The payback time for our purchased system was less than 5 years. The out-of-pocket cost for our 3,000 sq. ft. home for the PV panels was $11k after incentives, rebates, tax credits. We currently produce more energy than we use, but will have to reassess after the S arrives. It's MUCH cheaper with solar.

Yeah, the numbers sound about right, though in Oregon we might need more panels to achieve 100% electrical neutrality. We're atop of 750' mountain, so we do get a bit more sun when there is fog and low clouds, etc on the valley floor. But a 5 to 6 year payback would be great.

 

[Dave EV]

Yeah... Funny, here in Oregon, the solar calculator says we get 4 hours of sun per day!

PVWatts has the same estimate - that's for an ideally situated system tilted to the south. Solar insulation varies from less than 1.5 hours/day in December to just under 6.5 hours/day in July. As a rule of thumb for a system mounted on a south facing roof, it looks like you can estimate 1,000 kWh/year for each 1,000 W DC of solar panel in Portland. Here in sunny San Diego, one gets about 50% more energy per year - about 1,500 kWh/year.

 

[brianman]

I wonder if someone has a cheap sensor you can install so you could measure the actual sun exposure numbers for your house for a year.

 

[CyberDutchie]

We currently produce more energy than we use, but will have to reassess after the S arrives.

That's why I strongly recommend systems with micro-inverter technology. A micro-inverter is installed at each panel instead of having one large central inverter for all panels. It makes it very easy to expand your system when a few more panels are needed to support future EVs.

 

[Zextraterrestrial]

I wonder if someone has a cheap sensor you can install so you could measure the actual sun exposure numbers for your house for a year.

PG&E has a lending libraryhttp://www.pge.com/mybusiness/edusafety/training/pec/toolbox/tll/form/index.jsp#results - I borrowed this http://www.solmetric.com/
pretty easy to use

you can get total insolation #'s for your area from weather databases (NOAA maybe, I think)
the tool just looks at shading throughout the year


^
microinverters are cool because you can hook up a hydro wind and solar all together very easily

 

[SCW-Greg]

PVWatts has the same estimate - that's for an ideally situated system tilted to the south. Solar insulation varies from less than 1.5 hours/day in December to just under 6.5 hours/day in July. As a rule of thumb for a system mounted on a south facing roof, it looks like you can estimate 1,000 kWh/year for each 1,000 W DC of solar panel in Portland. Here in sunny San Diego, one gets about 50% more energy per year - about 1,500 kWh/year.

Great posts here from everybody, thanks!

I have an ideal roof facing almost due SouthEast, with a full hip roof giving me roof slope on every side, but primarily to capture ENE, E, ESE, and South sun. If needed I could even put some panels to capture some WSW, but not sure if I'd go that far. But I could get maximum capture on the sun from 7am to 7pm during peak hours in June/July.

 

[SCW-Greg]

That's why I strongly recommend systems with micro-inverter technology. A micro-inverter is installed at each panel instead of having one large central inverter for all panels. It makes it very easy to expand your system when a few more panels are needed to support future EVs.

Good feedback. The SolarCity sales guy did mention that the inverters (they install) do tend to wear out in about 10 years time, to be aware of that future expense. I didn't ask what they cost to replace. It would also be interesting to know what the life span of a micro-inverter might be too. I like the idea of flexibility.

He mentioned they also shop the panel manufacturers and can choose from a variety of technology, performance, and price ranges to suit geography and need best.

 

[CyberDutchie]

Good feedback. The SolarCity sales guy did mention that the inverters (they install) do tend to wear out in about 10 years time, to be aware of that future expense. I didn't ask what they cost to replace. It would also be interesting to know what the life span of a micro-inverter might be too. I like the idea of flexibility.

He mentioned they also shop the panel manufacturers and can choose from a variety of technology, performance, and price ranges to suit geography and need best.

I've read that they are pretty reliable. Enphase micro-inverters for example have a 25 year warranty. Also, in the event that one micro-inverter fails, it only affects a small portion of the total electricity output (only the one panel with the failing inverter). In the case of a failure of a more traditional central inverter unit, it will bring down the entire solar system.

 

[brianman]

it will bring down the entire solar system.

That sounds rough. Perhaps a longer warranty would be good.

 

[Timothy]

If you get a battery back up system rather than feeding in to the grid, my understanding is you don't receive whatever governmental rebates, incentives there are. At least that is what I was told when I installed my system nearly 3 years ago here in California. And the storage batteries are very expensive, I'm told.

My system wouldn't fit on the house, so I put the panels on a south facing hillside--long before I was thinking of an electric car. The number of panels I needed was an irregular shape, so I put in a couple extra panels to make a nice rectangle. I generated a little more juice than I needed, so what? And then I got the Tesla, and now have just a tiny surplus. Good planning, huh?--by accident!

 

[brianman]

If you get a battery back up system rather than feeding in to the grid, my understanding is you don't receive whatever governmental rebates, incentives there are.

I was under the impression that you can choose to split it between "grid feeding" and "battery refilling" such that you can get the rebates and have a local reserve for power outage scenarios. Perhaps it's not that simple (or is overly expensive) though.

 

[MarkR]

Who installed your system?

I had a similar experience. It costed me 8.5k to go full solar after rebates and tax credits. I haven't payed an electric bill over 20 dollars since. My system size is 5.28 kw, it makes about 32-35 kwh/day. Payback was 8.5 years, but that was conservative.

PEP Solar installed our system, but we had some challenges with them. It's a 6kW system with microinverters that produces up to 42kwh/day. Microinverters are ABSOLUTELY the way to go.

 

[MarkR]

That's why I strongly recommend systems with micro-inverter technology. A micro-inverter is installed at each panel instead of having one large central inverter for all panels. It makes it very easy to expand your system when a few more panels are needed to support future EVs.

The ability to add just the number of panels you need is a huge advantage of microinverters - and they allow the majority of you system to produce electricity at a high level if a few panels become shaded by trees, buildings, or clouds.

 

[brianman]

Likely off-topic and not practical but I'll ask anyway...

My house has basically a forest behind it. Suppose I built a treehouse-height surface and covered it with solar panels. Is this impractical because of the distance wire would need to be run (20+ feet) to the garage? Any examples of people doing something like this?

I presume I'd have to trim the limbs of nearby trees a few times a year to avoid blockage. Not sure what other maintenance would be required.

 

[Jason S]

I think the hard part is keeping the panels from getting literally blown away. That's why mounting to existing structures is preferred -- already have the height and wind resistance.

Building a huge wing on top of your house is a big hassle too. Better off mounting near ground level in an open space.

 

[Dave EV]

My house has basically a forest behind it. Suppose I built a treehouse-height surface and covered it with solar panels. Is this impractical because of the distance wire would need to be run (20+ feet) to the garage? Any examples of people doing something like this?

20+ ft isn't an issue. The longer the distance from your main service panel, the more expensive it gets due to trenching / wire costs, of course.

As brianman suggests, the biggest issue is building a suitable structure. Anything more than a dozen feet or so off the ground is probably going to be cost prohibitive. Otherwise, pole mounted systems are fairly common for that type of install. Also fairly common are "solar gazebos" where you build a shade structure using solar panels as the roof.

 

[Marco Aglio]

Why are not taken into consideration the black silicon panels can provide higher performance than traditional panels and with considerably lower costs?
At this point, you might also consider installing a panel on the car.

Google Traduttore

 

[wycolo]

In my area I feed power to the grid with solar and get credit for about 48 cents per Kwh. I then charge a night and pay much less, about 12 cents per Kwh. Overall I produce about as much as I use, even with an EV!

What kind of dreamworld is this?? In WY you pay 10+ cents per KWH, which is close to national average, and get credit for KWHs pumped into grid of 2+ cents per KWH. This is the same wholesale rate the electric coop pays for their electricity. As a producer of electricity why should you get more than the wholesale rate? I.E. why should other non-producing customers (or taxpayers) subsidize your setup so far beyond the wholesale cost of electricity? Also, have you been seeing these same prices for over a year? In WY the adjustment is made in Jan for the prior year, when they convert the virtual 10 cent monthly credits on your prior bills to the wholesale figure, and your imagined savings go poof.

Clearly for you there are massive subsidies in play. Do you have the breakdown for each of them?
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