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rockies
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# Posted: 3 May 2016 09:16pm
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An interesting article on a small house competition won by a group of Architecture Students in Texas. I always like reading about these types of competitions because the people designing them usually do a lot of research into the most efficient products and systems available.
http://www.greenbuildingadvisor.com/blogs/dept/green-building-news/texas-team-wins-ne t-zero-competition
I found there choice of an Ultimate Air ventilation system interesting.
http://www.ultimateair.com/
They also used a SEER 23 mini split air source heat pump.
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MtnDon
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# Posted: 3 May 2016 10:24pm
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When you build towards a net zero energy use you usually need something in the air handling / ventilation / heat exchanging department.
There are mini splits that get SEER 30 now.
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creeky
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# Posted: 4 May 2016 10:35am
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Nice house. They build to a price point so they make a fair number of compromises.
There are better ventilation systems. Better minisplits. Better windows. Etc. But for the price. That's a pretty good bang.
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rockies
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# Posted: 4 May 2016 08:29pm
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Creeky, what are they? How much electrical energy would a mini split use and can you use it on a solar power system? Some question with a ventilation system.
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creeky
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# Posted: 4 May 2016 09:16pm
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As MtnD points out there are better efficiency minisplits. The Fujitsu is 33.
I've seen a 120v that's 16 SEER. Consider that my a/c unit is 8 SEER. So 23 SEER is good. But not the best. Or was 23 a typo?
I've seen mini splits using in the low 100s /w. So they are doable on solar for sure. You'd want a lithium battery of course. 
Jeez, Fantech ERV is way cheaper, the european ... Zehnder is probably the best name in the business. I do see that Ultimate Air has improved their systems. Don't know how they stack up now.
Point of interest: For us small house folks this is my choice for ERV.
It breathes in and out. And at under 500 its a real bargain.
Uses 6 watts at max air flow. So no problem with electrical consumption.
Triple Glaze windows. Way more expensive. But more efficient.
That's why I said "price point." I like the build those brilliant students did. And for the budget. Just shows how good the systems have become.
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MtnDon
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# Posted: 4 May 2016 10:31pm - Edited by: MtnDon
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Quoting: creeky they are doable on solar for sure. You'd want a lithium battery of course.
A good unit, variable speed compressor is really needed, can work well on solar. A friend has been running a Sanyo mini split since about 2009. Don't recall the SEER, but not nearly as high as what is available today. On lead acid batteries. 2 Kw PV on trackers. No problem keeping the 1400 sq ft interior at 72 when it is 100 outside.
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creeky
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# Posted: 5 May 2016 09:11am
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the problem I have with my lead acid batteries in the hot months is keeping them cool. lead acid ages at double the rate at just 35C.
During the day the power will go straight from his panels to his inverter to his mini split. But as night falls its going to start drawing on the batteries. and the low efficiency of lead acid under high current draw means lots of heat. so hot weather. heat creating current. hot batteries.
How does your friend cool his batteries?
Or does he replace his batteries every two years like the RV folk?
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MtnDon
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# Posted: 5 May 2016 10:01am - Edited by: MtnDon
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He is fortunate in that like us, he lives in an area where A/C is not generally needed past 7 - 8 PM. So mostly he runs off the tracked array. I think he's into the 5th year of his 2 volt L-16's.
Not all RV folk replace their coach batteries every two years. We always got at least 4 years out of our golf cart batteries over the 30 years we owned a class C.
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creeky
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# Posted: 5 May 2016 11:17am
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Ya. There will always be those who are on the upper part of the time line. I just go by averages. It came as a real surprise to me to hear RV folk burn through batteries so quickly. Especially as they are part timers. I suppose the long idle periods (sulphation) combine with the deep discharge (when used) and high heat to shorten the battery life.
I imagine you would have been delighted to buy a battery pack that weighed 1/3 the weight and lasted 15 years with better charging and use efficiency.
Lead acid isn't useless. It's all we had. I'm in year 6 full time and my batteries continue to support my electrical use needs. They're just so darn inefficient. I need 1500 watts just to break even now.
Luckily there is a better solution. Lifepo4.
I certainly wouldn't want anyone going full time to get saddled with an inefficient, high maintenance ye olde tech when something better has come along. Which is why I continue to point out the obvious. Lead is dead.
Long live lithium.
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MtnDon
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# Posted: 5 May 2016 04:49pm - Edited by: MtnDon
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Quoting: creeky It came as a real surprise to me to hear RV folk burn through batteries so quickly.
No surprise that many RV folks run through batteries every couple of years. To begin with all the common RV's come with the Marine/RV type of battery for coach power. That's is a poor choice. many RV'ers don't have a clue about the systems that 'support' their RV. They don't think about anything until something quits. So batteries freeze over winters and get boiled dry when left connected to shore power for extended periods.
Fortunately for me I learned about golf cart batteries and why RV's should use them when I worked at an auto electric shop, part time while in high school. Our first RV (1976) came with a RV/Marine battery which I promptly ditched and replaced with two ray-O-Vac branded GC-2 for $CDN 160. They were still working when we sold that trailer 4 years later.
Quoting: creeky delighted to buy a battery pack that weighed 1/3 the weight and lasted 15 years with better charging and use efficiency.
I still struggle with the up front cost... In a similar manner that is why my new city car is a $17K Honda Fit and not a larger Honda, Acura or Beemer, or whatever fancier, larger vehicles I like, but don't like enough to pay for. .... The Fit does everything we want/need in local transportation.
I know lithium based batteries should last longer but that does not change the up front cost. The claims of extra long service life are not backed up with an extra long warranty with real teeth. Certainly the lesser weight is attractive to an RV'er. But weight means much less when the batteries are to be installed in a stationary location. But even then lead acid batteries don't amount to a very large % of the 10,000 lbs that a class c can weigh.
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creeky
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# Posted: 6 May 2016 10:43am
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I like your analogy.
More accurately. Lithium is your honda Fit. It's fast, efficient, modern. Fits to today.
Lead acid is a 70s Pinto or Rabbit. Slow, gas guzzling, breakdown prone.
Remember, even Princeton researchers found that Lithium has the lowest cost per cycle.
My concern is that by slinging disparaging and frankly erroneous comments Quoting: MtnDon claims of extra long service life are not backed up
Remember Black Cherry. The fellow who bought a lead acid pack and basically destroyed it by using it the first winter without recharging. I think the same thing happened last winter to another contributor here. I know when he bought his huge and expensive lead acid pack one of the comments he made was he was unsure whether lithium was proven.
And that is clearly not true. Lithium is proven. Thousands of users. Many years now. There's a guy online with a 5 year old pack who reports no loss of capacity noticeable. Etc etc etc.
Is your experience from the 70s relevant to today? Are you doing others a disservice by promoting an antique technology?
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MtnDon
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# Posted: 6 May 2016 10:58am - Edited by: MtnDon
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I don't recall blackcherry's experience.
Quoting: creeky Are you doing others a disservice by promoting an antique technology?
That is a misrepresentation. I'm cautious about spending a large amount of cash up front. The guy with the bus lost capacity unexpectedly when they found LFP had a bad reaction to extended elevated temperatures. I am not convinced we know all we should when it comes to LFP off grid. I know the limits of lead acid, but have also proven they can be lived with. I'm saying be careful. You're saying go ahead and spend the cash, you can't go wrong while you haven't used the technology yourself. I'll let you and others be the extended test base.
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creeky
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# Posted: 6 May 2016 01:59pm
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Quoting: MtnDon The guy with the bus
Here he is.
He did lose capacity with the high heat. At the same time as he was losing capacity lead acid packs were dying completely. As has been noted in other folks RV posts.
His 2016 update:
"January 2016 Update: After making adjustments to our setup described below, we seem to have caught the curve. Our most recent max discharge was 382Ah. So we're not continuing to see a drop in capacity a year later."
So that's 4.5 years of successful lithium use.
This is while most RVers are now buying their third set of batteries.
Lithium is proven. It offers the lowest cost per cycle. To dispute that is ... I just don't understand. Its not disputable in any real sense.
Far lower cost. Safer. More efficient. Charges faster (20%, more?). Discharges more efficiently (up to 30% at high drain). It requires less maintenance etc etc etc.
Proven, better and cheaper. Lithium is, realistically, the only proven effective off grid solar energy storage medium.
Nobody buying a lithium battery pack is a test case. They're wise consumers. They will smile from day one knowing that they have used their resources wisely. Enjoying the benefits of a better battery. Benefiting from state of the art.
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Bret
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# Posted: 6 May 2016 02:54pm
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This is an important discussion and I appreciate both sides of the "best battery" battle. Lead acid are inexpensive and easy to come by, but likely not as cost effective or operationally effective as the lithium phosphate. A concern I have is where can I order the lithiums.
http://www.electricmotorsport.com/ev-parts/batteries/lithium
This seems to be the only source except ebay and I am not convinced that that the batteries offered on ebay are of good quality. At least electromotorsport has winston and gbs, two of the most well known names.
So the debate goes on and I am getting near the purchase point. I recently received my solar bms designed for lithium from the kickstarter electrodacus. I am hoping that I did the right thing and only time will tell.
Technology is always blowing my mind. Just think, as kids we listened to the Lone Ranger on the radio and here we are talking about getting electricity from the sun. WOW.
Love all the back and forths on this forum. There's alot of insight and I always appreciate stealing others great ideas.
Best to all on this road.
Bret
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creeky
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# Posted: 6 May 2016 04:35pm
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I'm interested in your Electrodacus BMS. He's been at it a pretty long time now. Should be fun. And it looks really good.
Keep us posted.
ebay has this also from a US located electric car parts company.
140 per cell. or 560 for the 4 batteries. probably call them and make a deal.
I like the winston cells tho that your guy sells. the yttrium element intrigues me. Guess I'm a science nerd. The 7000 cycle 70% dod rating is pretty amazing too. You know. 20 year life span. Nice.
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rockies
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# Posted: 6 May 2016 07:10pm
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I am interested in the comment Bret made in his post about where to buy lithium batteries. He says that the only place other than ebay he can find is Electricmotorsport. I am not at the point yet of buying the solar power system for my cabin but since "Lifepo4" has been mentioned in several threads as one of the best lithium batteries around can't you buy them direct from the manufacturer (or their selected dealers)? Are lithium batteries not commonly available to retail or online purchasers?
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MtnDon
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# Posted: 6 May 2016 07:34pm
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Balqon, USA based seller of Winston cells and battery packs. Basically factory supported sales for the USA
Elite Power Solutions in AZ
AA Portable, in Richmond, CA
None of the usual PV equipment sources so far, for for whatever reason
As for buying from the manufacturer those are all Chinese. Good luck on that.
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