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We are on grid in Hawaiian Shores and looking to install solar. We currently have gas and electric. My sense is to install electric cells and change out the hot water to electric (its close to failure) as well as the stove (when it fails).
I see all sorts of discussion about the efficiency of PV panels versus water heating panels. I guess we could install both on the roof, but it seems simpler to just put up one type.
A second question is about inverters. Our electrician recommends an inverter on every panel if some are in shade (which they may be).
All insights welcome. Mahalo!
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you should do more research... You can't run a stove on solar (you can but it would be cost effective as you would need 50 batteries and 50AMP inverter and a truck load full of cash) get a gas stove. You don't run electric solar hot water heaters (again same reason) you run passive solar for hot water.
Good Luck!
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Yes, microinverters for each panel is the latest, and most effective technology.
No to electric stove or water heater.
Two types of panels is no big deal. Best overall efficiency is a big deal.
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First thing I would suggest is to figure out if/ when/ where your roof is shaded. Remember the sun travels a lower arc in winter. Second thing I would suggest is get multiple bids and get the bidder to put in writing where the panels will go on the roof and what solar angle are they going to aim the panels at. If you get multiple bids and keep asking questions you will probably find who you want to work with and what specs the contractor will be bidding on.
If you look around Puna you will see some panels installed on the southeast side of the roof, some on the south side, and some on the southwest side. Most panels seem to be mounted parallel with the roof plane regardless of solar angle but there are some installations with special brackets that actually aim the panels for maximum gain. You will probably pay more to get the job done right but in the long run it will probably be worth it.
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At this point the best bang for your buck is to convert to solar hot water and keep the grid. Since we did that our average elec bill is about $100/month. Crunching the numbers it makes more sense to wait for PV in Puna because we don't get the sun that the Kona side has. Once the price of panels drops a little more it will make more sense to convert to PV later. The problem with grid tie systems is that Helco charges you about $20 to tie to the grid, so even if you produce more power than you use, you're throwing $20 away each month. For now. In some areas the elec companies have raised the minimum grid-tie fee so much that some people pay nearly as much as they did for power before they switched to PV.
The price to convert to solar hot water was about $5500, but the net cost after the rebates and tax credits was about $1700. The ROI on the conversion for an average family is 18-24 months. Your ROI for conversion to PV will be 20-30 years, or longer if Helco jacks up the monthly grid tie fee. Since the panels are rated for about 30 years, your ROI will be occurring at about the same time they due for replacement.
There are a lot of people on PW who have made solar work without grid tie, and fairly inexpensively. They also use a lot less power than the average household.
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I put solar PV panels on my roof which is sloped about 15 degrees to the SSE. I'm in Eden Roc. I have convinced myself that a slight slope to the south, but otherwise nearly flat, is acceptable and may be as good as anything. This is because we have a lot of cloudy weather here in Puna. When it is cloudy the sun is essentially coming from directly overhead. A slight slope to the south seems like the best compromise.
I definitely concur about the solar hot water panels. I don't see any problem with sticking them up there next to the solar PV panels. Properly sized you will rarely need the back-up heater. Grid tied houses always use electric back-up because the installation is simpler and less expensive. When my brother got grid tied solar PV he also got solar hot water. They replaced his gas water heater with electric. His power bill is still the minimum because the back-up almost never kicks on. He lives in leeward Oahu though so it is very sunny and hot there.
I have often showered in the hot water from 150' of garden hose left out in the sun. Short shower but plenty hot.
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It wouldn't be rational to say that the shower I get from the garden hose is as good, what ever that means, as the one I get in my indoor shower with the gas water heater, but if you discount convenience and aesthetics it is close to the truth to say that I get as clean either way. That is the essence of going off grid, deciding what the bare minimum is that you can get by with, then focusing on how you are getting that rather than how you are not getting what you used to.
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Thank you all. Our plan is to stay on the grid, so I'm not clear why we can't use an electric stove. Our big energy consumers are the dryer, stove/oven, hot water and a small air conditioner.
Any suggested websites to learn more about this?
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If you have an electric stove, you should also invest in some HELCO stock.
Consult your financial expert.
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quote:
Originally posted by micro
Thank you all. Our plan is to stay on the grid, so I'm not clear why we can't use an electric stove. Our big energy consumers are the dryer, stove/oven, hot water and a small air conditioner.
Any suggested websites to learn more about this?
We have a small outdoor (lanai) kitchen that is 100% propane and we do all our baking in the small oven (for example:
http://www.amazon.com/Camp-Chef-Camping-Outdoor-Burner/dp/B0013LLSZG/ref=sr_1_1?ie=UTF8&qid=1379281659&sr=8-1&keywords=camp+chef+oven ) Not only does it use very little fuel, it doesn't heat up our house.
We dry our clothes on a line. In Puna your line will have under a cover. Again, our lanai suffices.
Our water is heated by solar.
Essentially we use VERY little 220. We have LED or fluorescent lights. Our biggest electricity usage is probably our fridge/freezer. Not much we can do about that. We use ceiling fans only when it's really needed. We have a solar attic fan that helps to keep the house cool. Our Helco bill is usually around $110/month. At that rate, PV doesn't (yet) make any sense. Our daughter is going off to college soon and our elec usage will go down to what... $80/month? (If I had a nickel for every minute she spent standing in front of the open refrigerator door, hoping that the contents had changed from the last time....) That is only $60 above the grid-tie fee Helco charges. I can't imagine going PV would ever "pay off" under current technology in our scenario.
